Webb Society Deep-Sky Observer's Handbook

Webb Society Deep-Sky Observer's Handbook

Volume 4 Galaxies

Coтpiled Ьу

the Webb Society Edited Ьу Kenneth Glyn Jones, F.R.A.S Written and Illustrated Ьу Edтund S Barker, F.R.A.S

With а foreword Ьу Professor Halton Arp (Mount Wilson and Las Caтpanas Observatories)

Enslow PubIishers Hillside, New Jersey 07205

Lutterworth Press Guildford and London

1981

То

Professor Наltоп Arp, uпrivаlеd explorer of galaxies, witll gratitude апd respect.

Copyrigl1t © 1981 АН

Ьу

the Webb Society

rights reserved.

No part of this book mау Ье reproduced Ьу апу means without the written permission of the publisher.

Library

о! Congress

\УеЬЬ

Cata!oging in Publication Data:

Society deep-sky observer's handbook.

First pubIished under title: The Webb Society observers handbook. lncludes- В ibIiographies. Contents: у. 1. DoubIe stars-v. 2. Planetary, and gaseous nebulae-v. 3. Ореп and Globular Clusters. -у.4. Galaxies. 1. Astronomy-Observers' manuals. 1. Jones, Kenneth Glyn. П. \УеЬЬ Society. QB64.W36 1979 522 77-359099 In the U.S.A. ISBN 0-89490-050-1 (vol.4) In the U.K. ISBN 7188 2527 6 (vol.4) Manufactured in the United States of America

10 9 8 7 6 5 4 3 2

CONTENTS . t of Illustrations Foreword Gen era1 Preface to the Han~book Preface to Volume 4: Galax~es

L~s

PART ONE: Properties of Galaxies Introduction and Historical Review 1. Classification of Galaxies 2. Distribution of Galaxies З. Formation and Evolution of Galaxies 4. Gaseous and Stellar Content of Galaxies 5. Nuclei of Galaxies 6. Seyferts, QSO's and Related Objects 7. Interacting and Peculiar Galaxies 8. Catalogues of Galaxies 9. Observation of Galaxies

ix xi xiii xv

1 7 21 25 31 35 37 43 51 53

PART TWO Catalogue of Galaxies Drawings of 156 Galaxy Fields

67 158

PART THREE List of Additional Objects Interacting and Peculiar Galaxies Seyfert Galaxies Variable Extragalactic Sources

197 198 203 207

А

1. 2. 3. 4. 5. 6. 7. 8. 9.

APPENDICES Emission Regions in И33 Emission Regions in NGC 6822 ТЬе Distances of Galaxies Non-Velocity Redshifts Examples of Arp's Peculiar Galaxies Further Drawings of Galaxies Faint Systems near NGC Galaxies Photographic Sources Bibliography

215 217 219 221 223 225 231 233 235

List of I11ustrations Wo1f'S C1assification of Ga1axies Hubble's Tuning-Fork Diagram Sandage's Вох Diagram Two Examp1es of Уаn den Bergh's Luminosity C1assification Four Examp1es of Vorontsov-Ve1yaminov's C1assification Arrangement of Arp's Pecu1iar Galaxies Distribution of Galaxies with ffi pg 15.0 - 15.7 star Distribution in М33 Two Examples of Smooth-Arm Galaxies 21-ст Radio Emission in NGC 6822 Boundaries of Radio Emission in NGC 5128 Synchrotron Radiation NGC 5128 in Ultraviolet Light composite Photograph of М51 Model of the Tidal Encounter in M51 NGC 4038-9 The Ring Ga1axy АО035 Model of the Formation of Ring Galaxies Intensity Gradients of Edge-on and Face-on Galaxies Surface Brightness Measures in NGC 1569 Surface Brightness Measures in А1009 Emission Regions in NGC 2403 Six Examp1es of Zwicky Compact Ga1axies Finding Charts for Мkn 335, NGC 262, Мkn 352 NGC 449, T~n 372, Mkn 3 Finding Charts for 1C 450, Мkn 374, Mkn 10 Мkn 382, NGC 2691, Мkn 315 Finding Chart for 3С 390.3 Finding Chart for BW Таи (3С 120) Finding Chart for OJ 287 Finding Chart for W Сот Finding Chart for Х Сот Finding Chart for АР Lib Finding Chart for 3С 371 Finding Chart for BL Lac NGC, 1C and Other Emission Regions in М33 Four Brightest Emission Regions in NGC 6822 Spectrum of 3С 273 Non-equi1ibrium No. 3 NGC 523 (Arp 158), NGC 2608 (Arp 12), NGC 2782 (Arp 215) NGC 3432 (Arp 206), NGC 3445 (Arp 24), NGC 3718 (Arp 214) NGC 4618 (Arp 23), NGC 4676 (Arp 242), NGC 5665 (Arp 49) NGC 5929-30 (Arp 90), NGC 7603 (Arp 92), NGC 7678 (Arp 28)

ix

8 9 11 14 15 20 24 27 30 32 38 39 44 46 47 48 49 50 55 56 56 61 6з

204 205 206 208 209 210 211 212 213 214 215 217 220 222 223 224

FOREWORD We are a11 aware that ga1axies are the fundamenta1 bui1ding bloc ks of the universe - the materia1 partic1es that fi11 the vo of the universe. But un1ike e1ectrons and protons, which 1ume '11 form а gas of a11 identica1 partic1es, еасЬ ga1axy is w~fferent from a11 other ga1axies. Natura11y there are broadly d~ff rent types of galaxies, but even the reasons why spiral d~la~ies are spiral and elliptical galaxies are elliptical are ~till not well understo?d. In actual ~act an e~or~o~s.range of fi1aments, jets, exploslons, deformatlon, multlpllcltles, . ersions, concentrations, colours, contents and various other ~~~ierences go into characterizing this class of object we call llaxies. То те, one fundamental mystery is why do galaxies show ~~cb an enormous range of characteristics. At first it was hoped that Ьу simp1e starting assumptions, а hot primeva1 medium of a1l identical protons and electrons, one could condense the galaxies into the different forms we see. It was investigated whether different-sized lumps, spinning with different amounts of angular momentum, would condense and evolve into the various kinds of giants, dwarfs, spherical and flat ga1axies we observe. It was really an excercise in extending the terrestrial physics we know out to understanding the universe. Вut basic questions such as why are some galaxies presently forming stars and others not forming stars, have proved difficult. Perhaps the greatest difficulty has arisen from the evidence of internal activity in galaxies. In the 1940's radio astronomy showed for the first time that many galaxies ejected excited gases from their nuclei. In 1957 it was realised that luminous matter was ejected from galaxies. From the 1960's onward it Ьесате evident that there were enormously compact concentrations of radiant energy called quasars in the universe, and that they had some relation to another kind of galaxy which has а very concentrated, active nucleus. In the search for а unifying physical principle from which а natural explanation for various galaxy forms will flow, а certain tension has been set ир between various researchers and schools of.thought. ТЬе competition between these different interpretatlons of observations is healthy, in that all conclusions are tested and challenged and new observations and new concepts are stimulated. Difference and cross-differences exist оп many levels, but the broadest division of opinion which 1 see in the interpretation of galaxies is the following: Many astronomers wish to start from а galaxy which condenses out of the primeval medium and using only th~ known laws of gravitation, nucleosynthesi.s and radiation, bUlld all the forms and phenomena we see in galaxies. ТЬеу use processes like stellar birth and death, recycling of interstellar

xi

Foreword

General Preface

medium, black holes and galaxy collisions to build models of all the phenomena we observe. А smaller group of astronomers wonder if galaxies are giving us evidence of new laws and process es iц the universe. Are there such things aswhite holes, creation of matter, non-velocity redshifts and origin of galaxies from compact bodies? As ап illustration of how various researchers view things differently we might discuss "peculiar" galaxies for а moment. An astronomer of the majority school would view а perturbed or distorted galaxy as а galaxy in collis ion with another, as ап opportunity to construct models of gravitationally-entrained stellar structures and gravitationally induced excited gas. An astronomer of the second kind would view all this as possible evidence for an internal explosion, а recent internal fissioning or the ejection of material in littleknown states. Now 1 think all sides will admit that going collis ion and normal gravitational their contorted forms. Most a~tronomers, also well admit that some other galaxies internal activity, ejecting material and,

some galaxies are undermechanics will explain оп the other hand, will are showing enormous exhibiting puzzling

expansions. The fact that examples of both kinds of galaxy activity are abundant and that they cannot Ье explained wholly Ьу опе approach or the other, does not теап that the basic tension between the two schools is resolved. The basic question still remains unanswered: Сап the observed phenomena in galaxies Ье totally explained with conventional physical mechanisms? 1f there is еуеп опе galaxy which сап incontovertibly demonstrate the operation of а new, or as yet unknown, physical law, then astronomy would have led human beings to а deeper and fuller understanding of the universe than physics has Ьееп аЫе to. This perhaps illuminates the reason why some astronomers work so diligently оп the observation and analysis of various exotic objects in the panoply of galaxy forms. 1t must also explain why тапу а non-specialist looks at the enormously varied forms of galaxies and thinks to himself - "1 wonder what is really going оп

there?" Halton Arp

xii

Named after the Rev. T.W. Webb (1807-1885), ап eminent amateur astronomer and author of the classic Celestial Objects for Common Telescopes, the Webb ~ociety exists to encourage the study of double stars and deep-sky obJects. It has members in almost every country where amateur astronomy flourishes. It has а number of sections each under а director with wide experience in the particular field ~he main ones being double stars, nebulae and clusters, minor pla~ets, superno va watch and astrophotography. Publications include а Quarterl , ' ' 1 es ап d special features, book reviews and У Journal conta1n1ng art1c section reports that ~over the society's activities. Membership is open to anyone whose 1nterests are compatible. Application forms and answers to queries are available from Dr. G.S. Whiston, Secretary Webb Society, C.E.R.L., Kelvin Avenue, Leatherhead Surrey Engla~d Webb's Celestial Ob.jects for Common Telescopes, , first p~blished lп 1859, must have been among the most popular books of its kind ever written. Running t~rough six e~itio~s Ьу 1917, it is still in print although the text 1S of more h1stor1cal than practical interest to the amateur of today. Not only has knowledge of the universe Ьееп transformed Ьу modern developments, but the present generation of amateur 'astronomers has telescopes and other equipment that even th е 1 ' pro f eSS10na of Webb s day would have envied. T~e aim of,the new Webb Society Deep-Sky Observer's Handbook is to prov1~e а s:r1es of observer's manuals that do justice to the equipment that 1S ava11able today and to cover fields that have not been adequately covered Ьу other organisations of amateurs. We have tried to make these guides the best of their kind: they are written Ьу experts, some of them professional astronomers who have had considerаЫе practical exper1ence ' , h the pleasures and ' problems of the W1t ahmateur astronomer. The manuals сап Ье used profitably Ьу beginners w ' enthusiasm and imagination. ' Н о will find т u ch t о s t'1ти 1 ate the1r owever, they are designed primarily for the more experienced amaEteuhr who seeks greater scope for the exercise of his skills • ive ас handb 00 k"1S complete w1th regard to its subject. The reader is g n an adequate hist or1ca ' 1 апd t h eoretical basis for а modern understand' 1ng of context f the pnysic ,а 1 ro 1 е о f t h е о Ь'Jects covered in the wider observ' о the Un1verse. Не is provided with а thorough exposition of ' 1 и d'1ng t h е construct10n . equipme1ngt methods ' 1ПС and operation of ancillary ' 1 е spectroscopes. Each volume Contai n such as micr оте t ers апdS1mp amateuns а detailed and comprehensive catalogue of objects for the ' h ап еуе made more perceptive Ьу the knor 1to d locate and t о о Ь serve w1t w е ge he has gained. We hope that th ese volumes w111 . abilit' епаЫе the reader to extend his 1es, to expl 't h' 1 challe ' 01 1S te escope to its limit and to tackle the ng1ng diffic u lt'1es о f new f'1е 1 ds of observation ' of succe with confidence ss.

xiii

Editor's Preface Volume 4: Galaxies This volume really takes us into the realms of deep-sky " t . extra-galactic observation, Ьу definition, extends one's c obJe "" n s.to the widest horizons of space, and at the saтe t"lme VlSlO ts us like time travellers, millions of years into the trапsроr , " t That the aтateur astronomer сап observe so тапу dlstant and P~~e;se forms of galaxies - the elemental 'building blocks' of dl "verse at large - is both challenging and encouraging. the unl 1 тапу fields of astronomy we are оп the threshold of new " nveries of the greatest significance. Most of this lies in dlSCO h e domain of high technology: - observa t"lOnS та d е Ь у or b"t" l lng t b rvatories, Ьу large-aperture optical and radio telescopes, and ~ s:oPhisticated (and expensive) methods of detecting gravityYves or neutrino particles. For the amateur with а modest aperture ~:lescope, however, the galaxies are still accessible, and with the ractical and theoretical knowledge which modern professional ~stronomy has made available, he сап observe them with an еуе much more informed than ever before. It is the purpose of this volume to make the observation of galaxies Ьу the amateur astronomer as profitable and enjoyable as possible. The reader is provided with а comprehensive and up-todate text covering the classification, distribution and evolution of galaxies, together with appropriate information оп their physical condition. In addition, some of the more esoteric systems such as 'peculiar' and 'interacting' galaxies, radio-galaxies and quasars are described. Finally, а thoroughly practical guide to the observation of all types of galaxies is given for the amateur to follow. All this detailed text serves to introduce the comprehensive catalogue of somw 275 selected objects, itself supplanted Ьу 156 telescope drawings made Ьу members of the Webb Society during the last 12 years. This form of presentation follows the well-tried method used in previous volumes of this series, and has Ьееп favourably commented ироп both Ьу reviewers and experienced amateur observers. We hope that this volume will Ье similarly well-received, since it represents the combined efforts of а ~umber of skilled and dedicated observing members of the Society, о whom the Editor unhesitatingly pays the highest tribute. h

The collation and presentation of all this diverse material as ОПсе again Ьееп undertaken Ьу the Director of the Nebulae ~~dt~lusters Section, Edmund Barker, FRAS, who has written all t е text, barring the historical reviews, compiled the ~~ alogues and lists and supplied the numerous illustrations. fls has Ьееп ап immense labour, but it has Ьееп а labour of love, Or Ье is ап amateur astronomer both in the literal meaning of

xv

Editor's Preface the term and in keeping with its highest tradition. Amateur astronomy in general, and the Webb Society in particular, have reason to appreciate his experience, skill and devotion: the Editor's debt is по less, and is gratefully acknowledged. АБ before, our Publications Officer, Eddie Moore, has maintained watchful еуе in proof-reading and vetting, especially in the final stages of production, and our thanks are due for his invaluable help at all times. а

We are pleased to acknowledge, also, the encouraging support and expertise of Ridley М. Enslow, Jr., President of Enslow Publishers, who ЬаБ contributed БО greatly to the success of this series. Finally, we wish to express our warmest appreciation to Professor н.с. Arp for doing us the signal honour of accepting the dedication of this volume, and for compounding this Ьу generously contributing а Foreword. In the realm of galaxies, Professor Arp сап claim mисЬ territory that is peculiarly his own (if the рип mау Ье condoned) and the kind appreciation of our modest efforts Ьу опе БО eminent in the field commands our deepest respect. Author's Acknowedgements. ТЬе author is grateful to the Editor, Kenneth Glyn Jones, for applying his knowledge of the history of astronomy to the historical review. Dr. Alar Toomre of the Massachusetts Institute of Technology proved а stimulating correspondent, while Robert Argyle and other staff members of the Royal Greenwich Observatory generously applied themselves to supplying data and processing photographs. Thanks are also due to the numerous astronomers who allowed reproductions of their work to Ье used and submitted relevant photographs. МисЬ of the research for this volume was undertaken at the Royal Greenwich Observatory, the Royal Astronomical Society and University College London. ТЬе author expresses his thanks to the Leverhulme Research Awards Committee for а research grant to aid in the compilation of this volume.

xvi

PART ONE: Properties ofGalaxies

INTRODUCTION AND HISTORICAL REVIEW INTRODUCTION. Th subject of this volume is galaxies, aпd following а natural 1 e' ca1 pattern in our series of observing Haпdbooks we arrive and °k~~nd of synthesis in which all the subjects о! the preceding at а ~ volumes are incorporated. Galaxies are visible in а wide varie~y of instruments from b'noculars upwards, aпd although little detail сап Ье таае out in ~all telescopes, such objects have always had а particular ~ascination for visual observers. Most of the 'popular' galaxies, such аа those in Messier's catalogue, are observed Ьу all amateurs at оnе time or aпother, but this rather limited approach tends to omit а considerable number of galaxies which are not particularly difficult to reach with moderate telescopes. It is the purpose of this volume to enlarge the amateur's scope in this field, aпd the reader will find тапу lesser-known galaxies featured in the catalogue section, while for those who desire to progress further still, additional lists of some more unusual - aпd interesting objects have Ьееn prepared. This volume, it should Ье noted, covers single aпd double galaxies, as well as objects comprising smallr. loose groups. Galaxies in groups of small aпgular size and large clusters wil1 he treated separately in а succeeding Handbook, Volume 5 (Clusters of Galaxies). Regardless of the instrument he uses, the visual observer will always wish to make out as much detail as possible. When we recall that spiral structure in galaxies was first det.ected only wi th th.e uэе of а 72-inch reflector. it тау Ье thought futile to attempt to observe such features in very much smaller telescopes. That this is not the case has Ьееn proved over aпd over again, for structure im spiral and irregular galaxies сап Ье seen with apertures as small ав 8 or еуеn б-inсhеs. In this volume we have maintained а t,wofold purpose; to show ~he.wide raпge of galaxies observed Ьу Webb Society members, aпd to ~~d~cate.the variety of lesser-known galaxies awaiting visual о servat~on - objects not listed in Atlas СоеН, the staпdard ~~eur.so~rce. Our sizeable list includes both very easy апа q е d~ff~cult objects to observe. In the Webb Society, our records ~o~tain Some few hundred galaxies which have Ьееn observed with e i ~scopes ир to БО-inсhеs in aperture. but of course, our object 1~_'O cater for observers who operate in the more соттоn б to v t~nch raпge. However, these comparatively large-aperture obser: ~on~ are extremely useful, for оnе of the greatest challenges in о serv~ng is finding out how much detail оnе сап make out with one's own t:lescope aпd comparing it with the results of others with super~or instrumentation. Such exercises are valuable for craining

з

2

Introduction

anа

Historical Review

the еуе, anа for this purpose there are по better objects to uti1iz e than the wide range of ga1axies in all their different forms. Fina11y а no'te is necessary regarding those sections of the text concerned with the properties of galaxies. ТЬе literature оп the subject is vast and is accreting at а rapid rate, во we сап give on1y а cursory survey of this field. Readers wi11 find that generous зрасе Ьаз Ьееп given to ga1axy classification, whi1e aspects of evolutionary theory Ьауе Ьееп on1y briefly treated. As c1assification systems are primari1y morpho1ogica1, ",е fee1 that the aтateur observer wi11 find this approach more rewarding. In еасЬ fie1d of galaxy research, however, an adequate bibliography Ьаз Ьееп provided for those whose interests тау 1ie in the realms of evo1ution, formation and dynaтics of these great extraga1actic systems. HISTORICAL REVIEW. ТЬе history of the observation of extraga1actic systems is long and venerable, but it ",аз not unti1 1924 that the nearest and brightest spira1 пеЬи1а, М31 in Andromeda, ",аз proved beyond dispute to Ье externa1 to the Ga1axy. The subject is thus decided1y confusing in.шanу ",ауз, and it wi11 Ье usefu1 to consider the matter in two distinct aspects; а) Pure Observation, and Ь) Theory.

Observation. ТЬе

Great Nebu1a in Andrошеdа is c1early visible to the naked in dark skies and шust Ьауе Ьееп noticed, and еуеп соштепtеd u..pon, in prehistoric tiшеs. However, the first recorded observation of this notable object ",аз the опе given Ьу the Persian аstrопошеr Abd-a1-rabman al-Sufi in his Book of the Fixed Stars in AD 954 where he described it аз 'а litt1e c1oud' near the star пи Andrошеdае. Strangely there is по шепtiоп of the Апdrошеdа Nebu1a in the starcata10gues published subsequent to that of A1-Sufi, and the next account ",е have of it ",аз not unti1 1614, when Siшоп Marius published Ыз controversia1 Mundus Jovialis. Marius sеешs to Ьауе rediscovered the nebula using an early version of the te1escope оп DесешЬеr 15, 1612: he described it аз shining 'with а whitish light which is ешittеd шоrе bright1y at the centre, where there is а pa1e and blurred glow, about а quarter of а degree in diaтeter. It sошеwhаt resembles the 1ight of а burning cand1e, shining through trans1ucent horn., when зееп at night frош afar. I e~e

ТЬе only other extragalactic sуstешs which had Ьееп observed ир to this tiше were the two Magel1anic Clouds, which had Ьееп noticed anа Ъxief1y

described Ьу Dutch navigators in about 1520, but being еуеП brighter and шоrе conspicuous than М31, they too шust Ьауе Ьееп kno~ to southern hешisрhеrе inhabitants of the earliest times. The first true te1escopic discovery of

а пе",

extraga1actic system

Introduction

anа

Historica1 Review.

оп October 29, 1749 Ьу the French ~strопошеr G - J 1е was made h сате ироп the nearer coтpan~on of the Andrошеdа t"l when е . h h е Gen ~, Ь" h 1ater Ьесате cata10gued аз М32, anа ",b~c bu1a Ne , w ~c I bout опе шiпutе in diaтeter, which appeared to describedtаз а 11 rays опе to the right and опе to the 1eft.' th w ои t wo зта , " хо t"1 сan thus Ье credited with the first known d~scovery Le Gene~traga1actic object, a1though, of course, h~ was not aware of ал . "ficance of Ыз feat. (The other сошрan~оп to the of the S~gnN~b 1а NGC 205 (М110) ",аз first observed Ьу Messier in Andro meda Caro1ine е u , Hersche1 шаdе an ~ndependen . t d~scovery . "1783) • ~n 1713, an d ТЬе АЬЬе N - L de la Cai11e ",аз the next discove~er of an extra1 t"c nebu1a when during Ыз remarkably product~ve опе-шan ~~p:~i~ion to the Саре of Good Норе in !751-b~' hte c(Naтe и6P~n L' а sша11 form1ess nebu10si ty' in Hydra. Tb~B о Jec, о.. ~n а ',11 'з 1ist of 'First с1азз пеЬи1ае') ",аз 1ater cata10gued аз С a~ е " М83 Ьу Messier: it has recent1y gained the d"~B t"~nc t"~on о f h av~ng produced, a10ng with NGC 6946, шоrе supernovae (four ир to 1968) than anу other ga1axy.

Within the next 30 years the number of galaxies discovered increased шuсh more rapid1y, шanу of them being ferreted out Ьу that assiduous comet~hunter, Char1es Messier. Of the з6 ga1axies listed in Messier's cata1ogu.e (described, of course, mere1y аз 'Nebu1ae') Messier himse1f ",аз the first discoverer of 11 of thеш: Ыз co11eague, Pierre Mechain, 17; J .Е. Bode, 3: J .G. Koehler, 2 and В. Oriani, 1. Thereafter, with the deep-sky penetration of Wi11iaт Hersche1, new discoveries of extraga1actic objects were шаdе in their hUndreds. However, not еуеп that prodigious observer ",аз аЫе to perceive anу c1ear distinction between pure1y gaseous (galactic) nebu1ae and the irreso1vab1e extraga1actic пеЬи1ае (ga1axies). The first significant c1assification оп these lines had to await the app1ication of the spectroscope to astronomy Ьу that rешаrk­ ab1e pioneer, Wi1liaт Huggins, who in 1864, separated the 'green' emission:-1ine gaseous frош. the 'whi te', continuous-spectrum пеЪи1ае. А 1itt1e before this, in 1845, the third Ear1 Rosse had observed distinct spira1 structure in М51 and this unique feature was эооп perceived in а few other nebu1ae.

direction~ сате with the app1ication ce1estia1 photography, especia1ly Ьу Isaac Roberts, "'ЬО in 1880 "'as the first to demonst.rate that М31 ",аз а 'spira1 nebula зееп in ~erspective'. The episode of the 'пе", star', S And., (actua11y а p~Pernova) in this зате nebu1a in 1885, a1though а bewi1dering оr~п~шепоп at the time, gave а post-dated clue to its extragalactic ~g~n. However, it was to Ье anoth.er 40 years before Hubble, о

f Further developments in this

5

4

Introduction and Historical Review

Introduction and Historical Review Ritchey and Duncan, working at the limits of the 60-inch, and later the 100-inch telescopes at Mt. Wilson, were аЫе, through the study of ordinary novae and Cepheid variables in М31 and М33, to demonstrate that these nebulae lay at distances far outside the en.virons of the Galaxy. Thus, in 1924, the scale of the Universe suddenly expanded in the minds of теn, and in another five years or эо Humason and НиЬЫе were to reveal that the Universe was physically expanding too. With these climactic events, the study of galaxies аэ such Ьесате truly significant at last, and modern cosmology began. Theory. Cosmology, the study of the Universe as а whole, сan Ье said to have remained largely in the realms of myth and folk-lore until the 18th century, when i.t attained what сan Ье looked ироn аэ а state of reasoned speculation. Naturally, conceptions of extragalactic systems had to wait и:роn the idea of the organization and entity of the Galaxy, itself, and it is Thomas Wright of Durham who is generally credited with the exposition of the form of the Milky Way, as а 'grind-stone' shaped disc of stars having the Sun at its centre. However, \oJright' s Original Theory of 1750 has more rec~ntly Ьееn shown to Ье more of а mystical or religious concept than а scientific оnе, anа it was William Herschel, some 30 years later, who put forward а more reasoned 'structure of the heavens'. Nevertheless, it was ироn Wright's idea that the German philosopher, Immanuel Kant, built his amazingly fruitful conception. In 1755 Kant postulated that тanу of the nebulae to Ье observed in the heavens were dist.ant 'Milky-ways' like our own stellar system, anа furthermore, that these 'milky-ways' were themselves organised into super-associations. This concept of island universes - as they were later described Ьу Humboldt - and their multiple grouping into what we now observe as clusters of galaxies was а remarkable example of prophetic vision - and that is all. Kant claimed that his hypothesis was based ироn actual observation of various 'spindleshaped' nebulae, observations made Ьу the French scientist Maupertuis who had suggested in 1742 that these objects were ellipsoidal bodies formed Ьу rotation. None of the objects observed or quoted Ьу Maupertuis - with the exception of the Andromeda Nebula - were extragalactic objects at all, but objects such as M13 аnа М22 (globular clusters) and sundry asterisms. The erroneous basis of Kant's theory is underlined Ьу the fact that he pointed out that 'these species of nebulous stars ••_. have а very near relation to the plane of the Milky Way' - а region whic h constituted а 'zone of avoidance' for later observers of galaxies. Despite this, the island universe concept was sust~ined, with vario Us vicissitudes, during the next 150 years. The beginning of the 20th

however, saw the astronomical world deeply divided ~s to

centu~Ytus of the 'white' and spiral nebulae, an argument wh~ch the ~ a t d in the so-called 'Great Debate' оп the Scale of the cu~m~naeebetween H.D. Curtis and Harlow Shapley in 1921. Curtis

iffi~~e~~at the Galaxy was comparatively small (about 17,000 light е

in diameter) and that the spiral nebulae were truly extra-

Y:~~tic at distances of 500,0?О light yea~s and upwards. Shapley

g ld contrary views оп both po~nts: he est~mated from the observed

~~ tribution of globular clusters that the Galaxy was much larger (;~o 000 light years in diameter) than most other astronomers ce~ted

and that the spiral nebulae were probably part of it.

~~ сan s~e that the 'Great Debate', although largely inconclusive, served to sharpen the issues involved: meanwhile, several misleading issues, such as the phenomenal brilliance of S Andromedae in М31 in 1885 (the existence of supernovae) and the rapid rotational values found Ьу Van Маanеn in some face-on spirals (erroneous) had to Ье disposed of. All these difficulties, аэ we have эееn, were swept away in the next few years Ьу НиЬЫе and his colleagues: Shapley's estimates for the dimensions of the Galaxy, were reduced but substantially correct, while Curtis' scale for the extragalactic distances of the spirals was upheld. At the same time the theoretical conceptions for an unstable (expanding) Universe, implied in Einstein's Relativity theory, and codified Ьу Jeans and Eddington, were also observed and quantified Ьу the Mt. Wilson astronomers. Since these comparatively recent, epoch-making days our a~tronomical horizons have widened enormously, and there сan Ье l~ttle doubt that the study of galaxies, in all their varied aspects, w~ll continue to Ье as rewarding and as exciting in the future as ~t has Ьееn in the past.

7

1. CLASS1FICAT10N

ОР

GALAX1ES.

INTRODUCT10N. astronomers У classification is а subject to which amateur Ga1 ах d· t. f feel drawn, аэ, with suitable aper t ures, · Боше 1n 1са lOn о often l"С classes сan ЬЕ determined (elliptical, spiral, irregular) the t аБ . . although extreme deta1l lS, of course, detectable only Ьу photographs taken Ьу large telescopes. ТЬе prime requisite of anу classification system is that it Ье ·ther too complex nor too simple; in short, it should present in ne10gent fashion such basic differences evinced Ьу the source :a~erial, which, in the present саБе, consists of phot~graphs. Astronomy is in а state of perpetual development, and 1n the past the classification of galaxies has shown а similar progress, but, while other fields of astronomy are nowhere near their termini, it is probably correct to эау that galaxy classification has now achieved an ideal state in the de Vaucouleurs extension of the Hubble system.

Beyond the classification scheme of de Vaucouleurs there are other classes of galaxies including Seyfert, cD and N galaxies, peculiar systems, luminosity classes and detailed descriptions of galaxy images as shown оп the Palomar Sky Survey prints. At first sight, therefore, it шау seem that we are now presented with an almost overwhelming array of different ga1axy types, but in fact the majority of all types sti1l fall within the classification of de Vaucouleurs, which is app1icable to at 1east 95% of known galaxies. Pre-Hubble Classifications. The optimum classification of galaxies was not possible until the deve10pment of astronomica1 photography, yet before this era the system devised Ъу Wil1iam Hersche1 encompassed тanу ga1axies, these fitting into his c1asses 1, 11, 111 and 1V. Herschel's scheme ~~ed bri?htness аБ а classification criterion, hut, re~ard1ess of ~ qua11ty of Herschel's te1escopes, it was 1eft to the 72-inch re lector of Lord НОББе to show spiral structure in Боте systems. t Опсе photography had reached а suitab1e 1evel, the detai1ed : ructure of шanу ga1axies Ъесате availab1e for study. For example, ta~reat dea1 of structure in ga1axies is to Ье seen оп photographs по e~ Ъу Isaac Roberts between 1885 and 1904, a1though Roberts made а tempt to иБе his plates for the purposes of c1assification.

W01;he first serious classification of ga1axies was developed Ьу at H,·who, in 1908, produced а system based upon photographs taken e1delberg. 1n this scheme planetary nebulae were a1so inc1uded,

8

9

C1assification of Ga1axies.

Classification of Galaxies. Ьи±

if these are removed from Wolf's categories quite а thorough spread in galaxy types remains. Notably, distinction is made.between ga1axies with по spira1 features and those with arms of varYlng intensity and degree of reso1ution. The Wo1f system, minus p1anetary nebu1ae, is shown in Figure 1, whi1e examp1es of воте ga1axies sho~ in the figure are: (1) NGC 4914; (т) NGC 3705; (n) NGC 4826; (о) NGC 4565; (р) NGC 3628; (q) NGC 4631 and (r) NGC 4559.

..

(11,,)

,~

(i)

(k)

тЬе НиЬЬ1е Classification.

/:,\;o-f;r~

'О

th year8 between the Wo1f c1assification and the modified _ In s ~ те of 19з6 numerous researchers uti1ised the Wo1f method e e Hubbl . and ev~n continued to ао 80 into the ear1y 1940'в. . thel r wo rk , . . , .t Sh 1 ' 1n d' ng other schemes dur1ng th1S perlod, ",е can C1 е ар еу s ar Reg 11 l'fication which ",ав Ьавеа upon degrees of concentration, 1928 с a8S . th 1 'k other ear1y schemes,is now по longer ln иве. Anо er ear у but 11 ehowever, that of Reyno1ds (1919) is of interest in that, in systern, ects , it para11e1s the first classification of НиЬЫе, upon тапу resp . h тапу current schemes are cOn8tructed. ",h1C НиЬЬ1е produced his first classification scheme in 1926 and а . l'on appeared ten years later. This revision brought into the . reV1S . fo1d the SO class of galaxy, one Wh1Ch, although not observed unt1l 19з6, had in fact been postulated.by.Hubble аэ ~ necessary class to f rrn а traпsition between the ell1ptlcal and splral systems. The r~ason for the late recognition of 80 galaxies was аие to the fact that оп 8mall-scale plates they appeared identical to ellipticals. While the latter have а steep intensity gradient, 80 types display an outer envelope superimposed upon an elliptical-like central structure; this outer envelope is similar to the exponential disks of spiral galaxies.

\Р)

Other changes introduced Ьу НиЬЫе in 19з6 were the inclusion of c1ass of ga1axy with а small bar in the nuclear region of an ordinary spiral and, finally, Туре 11 irregular galaxie8, objects showing по resolution into stars and containing much obscuring material, of which the best-known example is М82. а

:::

(t)

It was in 1936 that НиЬЫе a1so devised his famous tuning-fork di agram , shown in Figure 2. It was fel t Ьу НиЬЫе that this viewpoint, from elliptical to irregular, ",ав а function of rotation, and that the ЕО class galaxies would flatten as they врun, develop spiral аrшв, and eventually wind ир as irregular systems. This view will Ье discussed further in Chapter 3. Ordinary 8pirals

'111

ЕО Е5

80

~

8а

8Ь

8с

/~- ~-~~)-

8- -.- -~

~(lJ-6-Vj-

Barred 8pirals ~ Figure 1. Wo1f's C1assification of Ga1axies (1908).

8Ва

SBb

Irregulars.

SBc

Figure 2. The НиЬЫе Tuning-Fork Diagram.

11

1О

C1assification of Galaxies.

Classification of Galaxies. Post-Hubble Developments. The grea~ asset of the НиЬЫе sequence is its simplicity, anа his first (1926) classification was considered to Ье too simp1e Ьу ReYhol who had Ьееn struck Ьу the great variety of structure seen within th Q, basic ga1axy types. ОП the other hand, Вааае was convinced that ЬО е extension of Hubble's 19з6 scheme was necessary, anа stressed that examp1es of anoma1istic ga1axies cou1d Ье counted оп the fingers of ОП: hand. From Вааае' s viewpoint, therefore, such 1ater c1assifications а,' those of Sandage anа ае Vaucou1eurs were entire1y superf1uous, and su;; were the variations in the morpho1ogy of ga1axies that, Ьеуоnа the ' НиЪЫе system, on1y а study of p1ates cou1d give researchers insight into the variations within а sing1e c1ass. The 8andage Extension. Here we are presented with а c1assification system which increases the number of compartments devised Ьу НиЬЫе. Being structure1ess objects, e11iptica1 ga1axies are 1eft out of the picture, anа the concentration is ироn 80, norma1 anа barred systems, whi1e, as wi11 Ье эееn, space is given for subt1e transitions within each c1ass anа sub-c1ass, a1though these are not de1ineated. Taking the 80 c1ass of ga1axy, 8andage а! vided these into three suJJ. c~asses, 801' 802 anа 80з. The distinguishing features of these are ав fo11ows. 801

8imi1ar to an e11iptica1 system but is characterised Ьу а f1atter intensity gradient anа a1so disp1ays а thin p1ane, аэ with spira1 ga1axies.

802

8imi1ar to 801 but shows outer structure in the form of 'steps', un1iRe the smooth gradations of e11iptica1s.

80з

Again simi1ar to 801 but with the centra1 regions showing an absorption 1ane which, in the case of an a1most face-on system, is discernable virtua11y a11 around the centre. More ti1ted ga1axies show this absorption on1y оп оnе side of the centre.

Мanу 80 ga1axies, however, show morpho1ogy which differs а good dea1 from the аЪоуе examp1es, ranging from irregu1ar absorption features through аоиЫе nuc1ei to centra1 isophotes which appear to ье square. Such anoma1ies as these rather refer us back to the viewpoin t of Вааае mentioned ear1ier.

For ordinary anа barred spira1s, 8andage has аааеа sub-divisions, depending ироn whether or not ring formation i8 evident. Furthermor e , а transition type between Sc anа 1rr has Ъееn introduced, which is c1assed as 8а or SBd. From 80 anа 8ВО to Sd anа 8ва, 8andage has distributed the ga1axies into а Ьох diagram, shown ia Figure 3.

~ ---.-----~ So(r)

50

~Sb(r)

~ ... Sc(r!

'~

-

~~

~

:

~ 50I (5)

/~~Sd(rt

_~/I

/

/',;

Sd(s)

~-'-. - -,' Sbls) - ...../ Sc(s) "- ;'

Figure 3. 8andage's Ьох diagram showing spira1 (s) anа ring (r) subc1asses. The fu11 Ьох vo1ume is popu1ated with types of intermediate structure. The de Vaucouleurs Extension. 1n this system the c1assification compartments have a1so Ьееn extended from the НиЬЫе scheme, anа in such an extension much тоте data сan Ье accomodated in what is sti1l а concise method. The prime distinctions таае Ьу ае Vaucou1eurs are:

а) The иэе of 8А anа SB for normal anа barred spira1s. 1ntermediate саэеэ are 1abe11ed SAB.

Ь) The designations (Т) anа (s) for the presence or absence of ring stru~ture. Transitions are designated (rs), аn examp1e of the 1atter being NGC 4579 - SAB(rs)t. An outer ring structure is defiaed Ьу (R), and in such cases this precedes the main classification, as for NGC 4736 - (H)8A(r )аЬ.

с)

80 ga1axies are designated 80-, 800 anа 80+, these referring respective1y to ear1y, intermediate anа 1ate types.

d) 1rregular ga1axies ате c1assed аэ ordinary (1A), barred (1B) and mixed (1AB). Mage11anic C10ud types ате (1т) anа nоn­ Magel1anic types (10). А recent addition is for compact irregulars (C1), examples being NGC 1741 С anа D. d)

ComP~ct

el1iptica1s

(сЕ)

have been added to the E-type range,

а br~ght examp1e being М32, а fainter, NGC 448БВ.

ty In

ТаЪ1е

1 over1eaf is shown

ае

Vaucouleur's morpho1ogica1

Реэ; further detai1s of this wi11 Ье covered оп page 13.

13

12 Classification of Galaxies Classification of Galaxies ТаЫе

Classes

1. de Vaucouleurs' Morphological

Families

Varieties Compact

Ellipticals

Туреэ

Stages

сЕ

Ellip. (О-б) 1nterm.

"cD"

БВО

БАВО

S(r)O S(s)O S(rs)O

Inner ring S-shaped Mixed Early 1nt-erm. Late

БО-

БО

БО+ БА

Ordinary Barred Mixed

БВ БАВ

1nner ring S-shaped Mixed

S(r) S(s) S(rs) о/а

БО/а

а

Ба

аЬ

БаЬ

Ь

БЬ

Ьс

БЬС

с

Бс

cd d

Scd Sd

dm

Бdш

m

Бт 1А

Ordinary Barred Mixed

1В 1АЕ

1(S)

S-shaped

PecuJ..iars Peculiarities (all types)

Е+

БАО

Ordinary Barred Mixed

1rregulars

ЕО

1E0-1 БО

Lenticulars

Spirals

trype

Non-Magell.

10

Magellaпic

1т

с1 Р

Peculiari ty Uncertain Doubtful Spindle Outer ring Pseudo outer

Р

.

? sp (R) (R' )

The (R') stage оп the lower line of ТаЫе 1 results from the ~ that it сап at times Ье difficult to define real ring structure fa~ tightly wound spiral arms. This сап Ье seen in those БЬ systems ~~~~e the arms virtually make contact after each has made а full half-circle tu:n. Such cases as the latter are therefore classed as (R'), pseudo r~ngs. мапу amateurs are probably aware that the structure of spiral rшВ сап show considerable variations. 1n the НиЬЫе classification, :or example, spiral arms in Бс galaxies сап display morphology which raпges from regular aпd well-developed in early Бс systems to quite chao tic in late type ones. As а result of this, de Vaucouleurs has ~assified arm structure; some of these classes are shown in ТаЫе 1 where in the spiral compartments с to m refer to different a~т m~rphology. 1n this notation, m refers to massive arms, but not shown is ап additional symbol, f, which indicates filamentary form. Further additions, such as the symbol 2+, would indicate t~o main arms with braпches. At эисЬ а point as this the classification is quite complex, aпd further additions would overburden the system to the point of being unwieldy to use. However, а given researcher сап remove such of the notation ав he desires, aпd could eventually reach а stage where ~e scheme is ав basic ав the original НиЬЫе classification. 1n the catalogue of galaxies in this volume, тапу of those listed will Ъе given both their НиЬЫе aпd de Vaucouleurs classifications, but before this it is instructive to give а few examples of the de Vaucouleurs scheme. Among the well-known galaxies М31 would Ъе classed as SA(s)b aпd М33 as SA(s)cd. For а more complex example we сап cite NGC 1318 - (R)SAB(rs)O/a. Уап den Bergh's classification. This scheme is а luminosity classification, being based ироn the

ap~earaпce of the spiral arms of БЬ аnа Sc-1rr galaxies оп the Ыие

ir~~ts of the Palomar Sky SurVey. 1t was found tllat the most f~lnous galaxies have the most developed spiral arms; in contrast,

t~7nter galaxies have less bright, less well-developed arms.

1n

an~B system, БЬ galaxies are divided into five luminosity classes

SC~lrr galaxies into eight half-classes.

dis~his classification has а useful bearing ироn the extragalactic We ~~e scale, апа this aspect will Ье detailed in Appendix 1, во fOl~ а 1 here give details of the notation of this classification owed Ьу examples of each class in ТаЫе 2 •

hig~b or Sc 1 galaxies display long, well-developed arms of quite in thsurface brightness. Descending through 1-11~ 11, 11-111 to 111 е Sb group we are going down the scale towards the faintest-

14

15 Classification of Galaxies.

ar~

Classification of Galaxies

galaxies. Similarly, the Sc-1rr galaxies finish at 1V-V. the latt

be~ng the faintest. Additional symbols include (п) = nebulous arms

=: p~ tchy

(е!

arms and (t) = tidal effects due to interaction. Double s;rnb ~I ~nd~cate extremes,and symbols in parenthesis incipient structure. Taъ~ shows the respective di visions wi th examples alongside, while in ~igu;! are shown examples of ап Sc1 and ап Sc11 galaxy. ' ТаЫе

2.

Уап

den Bergh's System. NGC 4321

1rП

NGC 3310

Sb 1

Sc1

sы-п

SсП

3184

1rП1

4449

SbI1

SсП1

2403

1r+rV

5204

SЫ1-П1

s-rv

sып

S-IV-V

247

1r V

1e

1613

45

А further schems Ьу уап den Bergh concerns wha t he has termed 'anaen spirals, objects which appear to occur most in rich clusters of galaxi! The characteristics of these systems are found to Ье intermediate betw! gas-rich normal spirals and gas-poor SO types. The sequence for anaemi~ spirals parallels the Sa/SOa. Sb/SOb and Sc/SOc types, and is thus set as Аа, АЬ and Ас.

vorontsov-Velyaтin~v sysltem. °fO

tO h Ь All of the prev~ouS с ass~ ~ca ~опэ ауеееп concerned with ing degre es of basic structure with the НиЬЫе type аэ an underY trend. Unlike these, the Vorontsov-Velyaтinov system utilises g ~y~~ry large nuтber of syтbols to define the structural variations f galaxies аэ they appear оп the Palomar Sky Survey prints. In its ~etailed notation, this syste~ эеетэ ve~yolik? the answer to Reynol ds wish for а more deta~led class~f~cat~on than that of

Y.a:

ниьЫе.

Vorontsov-Velyaтinov is at pains to point out that his system is not а classification in the эепэе of all those we have detailed во far. All that his scheme does is to illustrate the wide variety of structure displayed Ьу about 30,000 galaxies to а limiting magnitude о! m 15.0. The full details of the notations will not Ье given here~gbut we сan give а broad coverage Ьу noting that galaxies are divided into ellipticals (Е) and flat (F). Other symbols are М. for large nucleus, n for small nucleus, Н for halo or haze, НН for several rings, в- for very short bar and ВВВ for very long bar. In all over 60 symbols are employed, and in Figure 5 we show exaтples of four galaxy types with explanations of the respective syтbols alongside.

=

вв

R

= long bar. incomplete ring

R = spiral arms emerging like а 1 to form а ring NGC 3184

= large пис. = connecting

Т

= tail

filaтent

N = large пис.

NGC 4321 Sc1

С

N

=

пе

= elongated

L

lens several rings

пис.

НН

=

SсП

Figure 4. Two examples of the уап den Bergh system of classifying spiral galaxies.

ne.L;RR ро

Ч~urе

5. Four

exaтples

of Vorontsov-Velyaminov' s classification.

16

17

Classification of Galaxies

Classification of Galaxies 1uminosity Classification. In 1957 Mo1'gan anа Mayall 1'eviewed ea1'lie1' studies of the diff_ e1'ences in stella1' content between the cent1'al (sphe1'oidal) anа spi1'al а1'т (disk) components of galaxies. 1ate1', Mo1'gan developed а spect1'a1 c1assification of ga1axies in which the spect1'al 1'egion is blue, anа gene1'ally 1'elated to the nuc1ei, 01', тО1'е p1'ope1'ly, nuclea1' 1'egions of galaxies. Mo1'g~

found that the co1'1'elation between fo1'm anа spect1'a1 арреа1'anсе is pa1'ticula1'ly close fo1' two ga1axy types, these а1'е а) I1'1'egula1' Mage1lanic Cloud-like systems anа spi1'a1s with an ' i~significant cent1'al luminosity concent1'ation anа Ь) giant ellip_ tlcals, such as М87, anа spi1'a1s in which а bright, aтorphous cent1'al region makes up the major part of the 1uminosity, as in the case of М31. In а) the spectrum is dominated Ьу ear1y-type stars апа emissiDn nebu1ae whi1e the Ыие anа vio1et spectral regions show strong hydrogen absorption anа bright emission 1ines simi1ar to those exhi Ы ted Ьу ga1actic Н II 1'egions. In Ь) the brightnes8 of the central parts is аие to ye110w giant stars; ga1axies with an intermediate degree of central brightness are shown to have an intermediate stellar population. As а re8ult of these observations, Morgan has classified the spect1'a of the central regions of these ga1axies in cDmparison with central star8, being either а, af, f, fg, g, gk or k, depending upon which spect1'a1 types make ир the greater part of the observed spectrum. As exaтp1es of the Morgan scheme we сап take М31 = kS5, М74 = fgS1 anа NGC 4449 = а1. In the first two eXaffiples the 'S' refers to spiral anа the a1'abic numera18 to the degree of e1lipticity о! the image. This latter symbo1 i8 used fDr al1 galaxy types, in cont1'ast to the Hubble scheme, where it is used only for el1iptic~~ Other symbols u~ilised are 'D' fo1' dustless ga1axies, '1' for 10w surface brightness objects and 'N' for galaxies showing small anа very bright nuclei which dominate the 1'est of the image, which i8 cha1'acterized Ьу extreme faintness anа small angu1ar size; more оп these particular objects wi11 appear а 1ittle further оп. The final symbol used in this classification is 'р' for anу galaxy with pecu1ia1' features, anа these again а1'е objects which we shall cDnsider shortly. The combination of spectrum anа form which is characteristic of this classification leads us smoothly into а further class of galaxy, the Seyfert type, Seyfe1't Galaxies. In 1942 Seyfert drew attention to а type of ga1axy whose prim e fe~ure was а small, bright nucleus set in spiral structure. А further characte1'istic was that the nucleus of such an object

sho wed а spectrum ~hic~ disp1ayed b~oaa~ strong emission lines. The .ginal six galax1es 1n Seyferts 11St 1ncluded NGC 1068 (М77), an O~~ ct in which both the nuclear region anа the outer, spi1'al °tJ~cture is bright. Another о! the original six, NGC 4151, differs ~ r m М77 in that i ts outer material is much fainter relati Уе to the n~~leus, алd, mo1'eover, shows structural peculiarities. Unlike other emission lines in ga1axies, those observed in the pectra of Seyferts are very wide, anа are interpreted in terms of ;as in the nucleus moving at high velocities, indicative of some kind of violent activity in the nucleus. The velocities in the gas аге in the 1'ange 500 to 10,000 km/sec, anа subsequent study of these has led to the identification of two types of Seyferts. In Seyfe1't 1 types the spectra show уе1'У broad, st1'ong hydrogen lines алd na1'1'ow forbidden lines; Seyfert 2 galaxies show spectra in which the forbidden lines are the saтe width as the hydrogen 1ines. Furthermore, the nuclei of Seyfe1't 1 types are variable, although the aтp1itude range is smal1, being well below ha1f а magnitude, while the associated time scales are a1so quite 1arge being reckoned in months. ' QSOs

anа

]1

1ас

Objects.

Classif~cation concepts. c~ often change as work оп the objects

concerned aevelops, апа th1S lS to Ье Бееп with Quasi-Stellar~bjects ~QSOs). As the пате implies, these object~ are virtually t~ellar ~n appearanc~, at least оп la1'ge-scale photographs such Wi~hPa~omar Sky Su~vey prints. This stellar appearance, a1;ng 1. . S rong ul t1'av~olet excess (extreme blueness) an emission.c~~:i~pec~~um ~a variabili ty at optical wavelengths, was for а • era е t~me the crite1'ia Ьу which QSOa were classified. Cu1'rently modif~ t· ' ho weve1', th е а ЬDve pa1'aтete1'S have in part 1'equired ... са ~on •. То begin. . th . t t Уе1'е identified . . . . W1 ~ ffi~s be.remembered that тanу QSOs i8 true th t 1n1t1ally Ьу the1r rad~o emission, and while it not hOld fa ~~bers of these а1'е optically va1'iable the saтe does being vari~~l ose QSOs which were discove1'ed optical1y these di8tance of е, but not to such а degree~ In addition the the red8hiftac~iOs~~11 affeci its appearanc€; at а la;ge distance re~ponsible for th 1ft the.1yman a1pha emission line, which is br~ng into th . е u1t1'av1olet excess, far to the red anа thus nOu1travio1·~ pJ.~tu~e abso1'ption features, resu1ting in either Fu. е emlss10n 01', at best, уе1'У 1i t:t1e. an 1'ther Unce1't . t . . 1 d SeYfe1't а ~ln у 1n classification a1so re1ates to 1'edshifts g ОУ м reso1ut. lax1es, as an object classed as а QSO оп plates of organ's N-~~~ т~y we(ll turn out to Ье а Seyfert, or еУеп опе of aX1ee page 1~). We sha11 now briefly conside1'

18

19 Classification of Galaxies

the cxiteria

Ьу

which the BL Lac objects are classified.

1n 1968 а radio source known as УНО 42-22-01 was identified with an object which had for some time Ьееn considered to Ье а variabl e star in Laeerta, and whieh was given the nomenelature BL Lae. РТОт а morphologieal viewpoint, BL Lae, objeets are varied, being eithe!' eompletely stellar, eompaet elliptieal galaxies or nuelei of galaxi ei 1n addi tion they show а non-thermal optieal eontinuum and а eomplet laek of emission lines plus rapid light variations and strong е polarization, whieh is also variable. While the optieal variability is тиеЬ greater than for QSOs, other BL Lae features are similar, exeept for their laek of emission lines. Seyfert and N-galaxies, QSOs and BL Lae objeets form an interloeking group of objeets with тanу similar eharaeteristies, and the possible meehanisms whieh give rise to sueh vast outflows of energy, plus further exeursions into ~lassifieation problems, will Ье taken ир in Chapter 6. Markarian and Haro Galaxies. The use of speetroseopy as а method of elassifiaation is illustrated in the case of Markarian galaxies. These are objeets whieh display extremely strong ultraviolet eontinua; most are eompaet and posess stellar nuelei, while тапу Ьауе Ьееn found to Ье Seyfert galaxies. Haro galaxies are, in the main, distorted or very irregular in strueture, this being evident еуеn оп their small images оп the Palomar Sky Survey. Seleetion of these objeets Ьу Haro was made оп the basis of ultraviolet exeess оп Schmidt teleseope plates. Zwicky Compact Galaxies. ClassLfication of galaxies depends а great deal ироn the resolution оГ the original elassification photographs. For example, if the Seyfert galaxy NGC 4151 were situated at а great€r distanee, its faintish outer regions would not Ье observed in their entirety, and it could well thus Ье classed as an N-galaxy. ТЬе aspect of plate scale and resolution is well brought out in the definition of eompaet galaxies given Ьу Zwicky in 1964, viz., that they are objeets just distinguishable from stars оп 48-ineh Sehmidt plate • Also applicable is а surface brightness criterion 2 of 21 mag sec , whieh is the lower limit. Furthermore, Zwicky als o included compact parts of galaxies in his эсЬете, these ranging from bright nuelei to bright, small emission regions. ТЬеэе eompact systems do not present а homogeneous group of objeets; of their morphology as revealed Ьу high resolution photo· graphs, there are jets, rings, spirals of various types (some distorted) аэ well аэ Ыие, irregular objects, which are virtuallY extragalactie Н 11 regions.

Classification of Galaxies. сотт оn with galaxies of other types, numbers of Zwieky objeets n 1so Seyferts, including the first catalogued compaet, 1 Zw 1. ате а ent observations Sargent has discovered that а small number of In re~ts ате in faet galactic stars, while others are sta1's super~ompaed ироn the images of faint, distant galaxies, thus giving the ~трОЭ . imp1'es sion of а eompact obJect.

1

1 teraeting and Peeuliar Galaxies. n In 1959 Vorontsov-Velyaminov published Ыэ first Atlas of 1nterting galaxies and а second Atlas appeared eighteen years later. ~~pIS Atlas of Peeuliar galaxie~ (1966) eontained 338 objeets, all photographed with the Hale 200-lnch telescope, and а good тапу of these also feature in the Vorontsov-Velyaminov works. ТЬе objects contained in the А1'р atlas are only а sample of known peculiar systems, and а revised and extended atlas is now in preparation, plus а similar atlas for the southern sky. 1t would Ье easy to aceept interacting and peeulia1' galaxies аэ new classes of objects, but виеЬ аn idea is soon dispelled Ьу аn inspection of, fo1' example, the Arp peeuliars. Fo1' all but 45 of these а basie НиЬЫе type is distinet, and the эате сап Ье said for тапу of the Vorontsov-Velyaminov objeets. Fu1'the1'more, еуеn some of those interaeting and peculia1' systems to whieh по НиЬЫе type сап Ье currently assigned тау Ьауе оnее Ьееn normal as regards type, and тау revert back to the эате in futu1'e epoehs. Further excursions into the proeesses oeeuring in these galaxies will Ье made in Chapter 7, and to eonelude this chapte1' we show overleaf the method Ьу whieh А1'р has arranged the various objeets in his atlas. The numbers oecuring unde1' each type refe1' to the nuшЬе1'В of the respeetive objects in the atlas.

20

21 Classification of Galaxies

LOw S BR.

"_ i

SPl..IT ААМ

.7-12

WITH ASSOCIATED

~ SPIRAL \

RIHGS

ОПАСНЕD SEGMENТS

""-'.

\

2. DISTRIBUT10N OF GALAXIES

/'

THFlEE-ААМЕD 819-21 ОNЕ-ААМЕО

~

GAL I S I

WITH JETS

~.~14'-'" Im~~~:~~~ENTS

. . . .\ ..8'

"22-" OНE,.,Avт ....

""->0

АХ Е

DIFFUS[ COUNТER-TAILS

". ~

8162-172

:::..-----

~ NARROW COUNТER-'A'L.S

GALAXIES ~~ NАR:I:~-;~:АNЕms

IHTEGRAL 51GN

-"-36

,~~

8'79-'93 "'AТERIAL EJ[CTED

FRQW NUCLEI

8194-208 IRREGUlARJTIES,AВSOAPТION .НО RESOLUTION

*209-214

/

ADJACEm LOOPS

IRREGULAA

SPlRALS 8'02-108

Е

~ AND

\

~::8

CONНЕСТЕD то

R[PELLING SP1RAl AAМS

8215-280

АРРЕАААНСЕ

.....

OR~~I~:-L o\RMS

of F155_0H

8109-111.

/

~33-2~

CLOSE ТОАНО 5P1RAlS

CONC[NTRIC RINGS

8227-231

РЕАТиА81Н'

""-132

/ / WITH НЕАА8У E-LIK~----- ':';;~,~

DOU/BLE \GALA~-====:;::::~:!.:~7:RNS ~ ~2Т5-280 WlNO ППСТS

INFALL АНО АТТRАСТЮN

.287-292

tIt"'TERIAL EM"'H"TIHG FJtoм Е GALAXIES ·137-145

LOНG F"ILAМENТS

-294-297

8281- 286 GROUPS OF GALAXIES

INTRODUCTION. 1 this chapter we shall fairly briefly consider the apparent 'st~ibution of galaxies оп the eelestial sphere as well as their dk distribution out to а distanee of about 10 Мре. Beyond this врасе . . lie the nearest large cluster of galaxles, the Vlrgo cluster. s The a.mateur astronomer, upon glancing at the Atlas Coeli charts, obtain а good indication of the distribution of galaxies ~~ghter than 13 mag. From the point of view of а whole-sky view of good percentage of galaxies down to 15 mag, the Coeli eharts are :ot useful, yet it is at these lower magnitudes that the numbers of galaxies increase substantially. More galaxies are to Ье found оп the SAO charts, all of them NGC anа IC objects, and the magnitude limit is thus considerably lowered. А further aspect noticeable оп the SAO charts is the clumping of galaxies in regions of various angular sizes. Many of the objects in these amalgams are members of large clusters of galaxies, and so fall outside the seope of this volume; other, smaller groups are valid for inclusion here, aceording to the criteria explained in the introduction. Field Galaxies.

·311-321 ............ СНAJIб OF GALAtlES

·322-352

Figure 6. Arrangement of objects in the Atlas of Peeuliar Galaxies. The diagram shows the major peeuliarities whieh determine the classification. (Reprinted eourtesy of H.~. Arp and The Astrophysical Journal, published Ьу the Unlversity of Chieago Press: ~ 1966 The Americal Astronomical Society).

ву field galaxies we mean those systems which, as far as сап Ье aseertained, are not members of either large clusters or smaller groups. In the 1930's galaxies were generally regarded as mainly isolated objects, only а small percentage being known to oecur in clusters. Nowadays, however, it is realised that isolated systems are no~ the norm; in the galactic neighbourhood, for example, true fleld galaxies are not common, and among their number are NGC.13 1 3, NGC 2903, NGC 6744 and NGC 6946. If we take а sample radlUS of 50 Мрс from the Sun, we find that rnany groups of galaxies, ;~ well as the Virgo Cluster, lie within this volume. The number of ~eld galaxies distributed in the area тау well only amount to 1~/o о the total known number, and even some of these тау Ье members of as yet unrecognised groups.

Q!oups and Clouds of Galaxies. int TO be~in with it is neeessary to fit the words 'group' and 'cloud' Lea~ithelr.order of plaeement in the hierarehy of galaxy distribution. clustng aSlde single galaxies, the sequence is: binary, group, cloud, er and supereluster.

gal~h~re

are two analogies whieh тау help to define а group of starXles, and both of these compare with the cluster membership of ОГ g:las.described in the preceding volume of this series. А group all y baxles comprises over 2 distinet objects that are gravitationОГ а ound for а period of about 109 yr, or are related as products Соттоп formative event during such а time scale, but are now

22

23

Distribution of Galaxies по longer gravitationally bound. ТЬе former of these two is analog

to star elusters and the seeond to stellar assoeiations.

Distribution of Galaxies Taыe

O

11!

ТЬе faetor Ьу whieh а group is first suspeeted or identified iB eontrast with the field. Iп eases sueh as Stephan's Quintet or ~ Seyfert's Sextet (NGC 6207 group) this eontrast is obvious enough, but for more extended groups, sueh as the NGC 1023 опе, elose and obvious elumping is not the ease. То Ье absolutely sure that а given number of galaxies eornprise а group of extended angular size, eertai data is required; radial veloeities are neede to deterrnine the n differenee in veloeity (ДV ) between the galaxies, plus anу general sirnilarity of rnorphologiea~ type, apparent rnagnitude and angular diameter. Finally, eorreetions тау Ье neeessary to the rnagnitudes of the galaxies to allow for the effeets of galaetie obseuration or аnу absorption within the galaxies thernselves.

Clouds of galaxies are larger eonglornerates, and will inelude groups. For exarnple, the Loeal Cloud eornprises all groups within about 7 Ире. Непее we are here eoneerned with interrnediate-sized groupings, with absolute diarneters of about 1 to 3 Ире. Within such а volurne is eontained the galaetie neighbourhood whieh in turn iпеюrроrаtеs the Loeal Group of galaxies whieh we shall diseuss а little further оп. The Galaetic Neighbourhood. То

define sueh а region of spaee is, to а certain extent, а diffieult task. If we use the 9.1 Мре set Ьу Таттan and Kraan (1978) this partially takes in the Loeal Cloud radius of 7 Мре used Ьу de Vaueouleurs. Wi thin thi s region are eonsidered to Ье 1}1 galaxies of whieh 33% are possible field systems while the remainder are eoneentrated into 8 groups. Noteworthy in the distribution of these systems is their strong eoneentration towards the supergalaetie plane, whieh describes а band nearly perpendieular to the plane of the Galaxy, and, at greater distanees, ineorporates the Virgo eluster of galaxies. There still rernain problerns regarding the definite assignrnent of nearby galaxies to groups, and further observations are needed to srnooth out anу existing arnbiguities. While Татman and Kraan list 8 groups within 9.1 Мре, de Vaueouleurs eonsiders there to Ье 54 't within 10 Мре, inelusive of the Local Group and the next group to 1 whieh lies in Seulptor, and eornprises 6 or 7 late-type spirals. We shall eonsider the Loeal Group next, but first show in ТаЫе 3 ove t ' leaf the 14 nearest groups aeeording to de Vaueouleurs. It is instruetive to look at the angular sizes of thезе groups, whieg ar~ quite eonsiderable; 5 have largest diameters between 20 and 28 аР the rernainder, barring the NGC 5128 group (300 long) between 7 ап а 200.

.--Group/Cloud to-

scl gp М81 gp

СУп 1 cld NGC 5128 gp М101 gp NGC 2841 gp NGC 1023 gp ТЬе

3. Groups of Galaxies within 10

1"1embers def. ров. 6 5

5 6 8 6 6

1 23 8 1 20 10 8

prQb 4 6

2

Group/Cloud NGC 1"166 CVn 1"196 NGC

2997 gp gp I I eld gp 3184 gp Сота 1 eld NGC 6300 gp

1"1ре.

def.

1"1embers pos. prob.

5·

5

5 5 10 4 15 5

6 2 8

2 12 6

12 3

Local Group.

Loose groups of galaxies are distinguished Ьу а laek of coneen~ tration at the centre, and the Loeal Group is а good example of such а group. The dorninating members are the Galaxy and 1"131, and the other members are made ир of а preponderance of dwarf irregulars and dwarf ellipticals. Ву 1965 the knоwn number of members was 26, but this has risen in recent years Ьу the diseovery of very low surfaee brightness systems such as the dwarf irregulars in Sgr, Scl and Phe and the new companions to 1"131. other possible Loeal Group galaxies тау skulk behind regions of obscuration in the plane of the galaxy; 1С 10 has Ьееп knоwn for шan~ years to Ье а heavily obseured objeet, and more recently the much more obseured 1"1affei galaxies have bee~ unearthed. Мanу galaxies in and beyond the Loeal Group are affeeted Ьу interstellar material, and еУеп 1"131 and its eompanions are in sueh regions. ТЬе Zone of Avoidance.

The most obvious region of the sky in whieh the effeets of the interstellar medium are to Ье эееп оп galaxies is the Zone of Avoidance. This is formed Ьу the great elouds of dust in the plane of the Galaxy, and its obseuring properties are irnmediately apparent when only the brightest galaxies ир to 13 rnag are plotted. Ав ~alaxies of fainter magnitudes are plotted, so the Zone of Avoldance beeomes even rnore prorninent. The effeets of all this m(aterial will either effeetively dirn the outer regions of galaxies, 1е 10, 1С 342) or render them eornpletely invisible, as is the саве with the Maffei galaxies, whieh are only deteetable at radio ::ve~engths. Overleaf, in Figure 7, are plotted galaxies in the angnl~ude range т = 15.0 to т = 15.7, and the Zone of Avoiddic~ :s C~early iRgevidenee, alBRg with the extrernely Ьеауу в rlbutlo n of galaxies within the given rnagnitude range.

24

Distribution

о!

25

Galaxies

3..

.

..........

FORМAT10N

AND EVOLUT10N OF GALAX1ES.

lNTRODUCTION тЬе appearan ce of galaxies at the cu-rrent еросЬ leads ив to that they are at а certain stage in their evolutionary supposcee Why do the different galaxy types look as they do; what is equen • s . past history; апd what will happen to them over the large time the~rs of the future? These are questions which have been asked and sca et~gated over тanу years, and which are sti11 being pursued inves ... . " with the aid of both theory and оЬsеrvаtз.о~. It wi11 Ье rec:a11ed from Chapter 1 that ниьы1e considered his pho1ogica1 sequence of 19з6 to Ье evo1utionary; that from E-type mO~axies succesive stages of rotation fina11y resu1ted in the Irr ~;pe systems. Tb~ reverse of this idea has a1so be~n consid~red, but эоте iпdiсаtз.оп of the aeotual stages of gа1асtз.с evolutl0n are now beginning to emerge. At the present time, the ev01utionary aspect of ga1axies has reached а quite сотр1ех 1еуе1; not оп1у are there the obvious features of ga1axies which seem to Ье partia11y exp1ained (spira1 arms) but a1so radio emission and the effects of the environment from which galaxies form. ТЬе topic itse1f is а сотр1ех опе, and in this chapter we sha11 consider the fundaтenta1 processes Ьу which the observed structure of ga1axies is achieved, as we11 as the related subject of primeva1 ga1axies. ТЬе

ages of Galaxies.

Nowadays, when we 100k at the НиЬЫе sequence, we view it from standpoint which differs from those enumerated аЬоуе; it is now вееп as demonstrating that it is the initial ~onditions which give rise to the НиЬЫе type of а ga1axy, and that the overall ages of а11 ga1axies are about the saтe. ТЬе paraтeters of the initia1 gas c10ud from which а ga1axy forms, therefore, determine its current1y observed structure. а

Usefu1 objects to uti1ise in the study of some ga1axy ages are globular c.1usters. We Ьауе вееп from the previous уо1ите in this ser" Ье les th~t ~beвe are o1d objects, and the fact that they are to th found lП lrregu1ar ga1axies висЬ ав the Mage11anic Clouds shows th at , for а11 their young Ыие stars and associated Н 11 regions, ese th e ga1axies are o1d. From висЬ objects as g10bu1ar c1usters and c~1ours gal а:Х:lе' of. ga1axies, it appears that the 10ages of а11 norma1 S lп the НиЬЬ1е sequence are about 10 yr o1d.

staFur~her evidence оп ages сan Ье derived from the brightest Sha;S lп nearby ga1axies. Here what сап Ье done is to use the оп ае С of such giant branch stars which are bright enough to register ГО х o1our-Magnitude diagraт. 1п the Draco dwarf e11iptica1 ga1axy, ha.lo е:х:атр1е , the giant branch вЬаре is very simi1ar to those of globu1ar c1usters in the Galaxy and also simi1ar to the centra1

27

26

Formation and Evolution of Galaxies regions of М31 aud М32, which again indicates ages of the Saтe order. The idea that the ages of normal galaxies are оп а par i8 say that in al1 of them а large population of old, red stars mU8t t o exist, and part of the red star distribution is now thought to Ье at the root of the formation of spiral arms. Spira1 Arm Formation. А galaxy becomes recognisable through star formation: prior to this it exists as а gaseous cloud, mainly composed of hydrogen, and of а given size and mass. These latter paraтeters will determine the Hubble type of the resulting system, оnсе contract_ ion of the cloud has reached the point where stars begin to form. At ВОте point, therefore, а young or primeval galaxy will appear. We shall pass оп to the subject of primeval galaxies further оп in this chapter, and see what evidence there is for such object8.

Formation and Evolution of Galaxies. the latter being the e and the flat disk component, ' ' 1 s. 8uch centra1 bulg , h'ch spiral arms appear.ln the f case о splra regions l~r: ~ st seen edge-on if the two components are to Ье galaxies bVi~US examples are М104 and NGC 4565. Depending upon вeen~ and °d' k galaxies are forming stars at the current еросЬ, lS ' 1Ear 'ler sys t ems type, some in late-type spirals plus some lrregulars. thes e Ье g th-arm spirals which we shall discuss later) do not О' and smoo , (S S t forming at the present time. вЬО"" s ars

Young stars are blue objects, and, as colour photographs of spiral galaxies show, are arranged in spiral structure. 1n other systems, such ав irregulars and interacting systems the b1ue star distribution is more random. The fact that the stars forming the arms are young shows that, оп cosmo10gical time scales, they have not Ьееn in existence for long. 1n: looking at such photographs, it appears that the spiral regions of galaxies are free of other ste11ar types, but this is not the case, ав an underlying layer of red stars exists. 1n distant galaxies particularly. these red stars сan Ье complete1y masked Ьу the bright, young stars. 1n Figure 8 opposi te is an illustration таае up from а photograph of М33. ТЬе original plate was таае up Ьу superimposing а blue-light negative оп an infrared positive, which makes the b1ue stars show up as black аnа the red stars as white. 1n the figure the red stars, extending out from the nuclear region of M3J" сan Ье seen to form an elliptical disk; superimposed оп the disk сan Ье seen, the b1ue stars, forming the spiral arms. 1t is obvious from such ste11ar distribution that the young, Ыие stars must have formed within the red star population (in the Saтe plane) and the currently accepted explanation of this is the density-wave theory of spiral arm formation. This theory was first proposed Ьу Lindblad and later resurrected and developed Ьу Lin and Shu in 1964. 8ince then they, along with the 8troms at Kitt Peak, have .юrkеd оп the idea in both the observational and theoretical fields. 1t is stressed that they ао not pretend to Ьауе а theory about every spiral ga1axy; however, the idea goes а long way to explain how spiral arms сan Ье formed аnа maintained over quite large periods of time. Disk galaxies (spirals and 80's) possess two components; the

Figure 8. Disk and spiral arm star distribution in М33· Photograph kindly supplied Ьу M.F. Walker, Lick Observatory.

29

28 Formatio~

Formation and Evo1ution of Ga1axies

and Evolution of Galaxies

Spiral arms in galaxies are believed to form in the following way. 1t is considered that spiral patterns are quasi-permanent density-waves in the red stars of the disk, but the initial form_ ation of the waves is at present uncertain. With the densitywave in existence, gas in the disk of the galaxy encounters the crests of the waves at supersonic velocities. As this occurs, а shock wave results, compressing some of the gas and resulting in star formation in the observed spiral form. Spiral arms form€d in such а fashion should exhibit certain characteristics: а) dust lanes should Ье seen near the inner regions of the arms; Ь) in intermediate arm regions ОБ star associations should Ье apparent, together with Н 11 regions formed from earlier compressed gas; anа с) older clusters anа associations formed from much earlier compression should populate the outer arm regions. То date observations Ьу Lynds have shown the dust lanes оп the inner regions of the arms, while photometry Ьу Visser anа others has demonstrated that the predicted density-waves are apparent in the red, disk star distribution in М81 anа other spirals.

Smooth-Arm Spirals. Not all spirals exhibit the star anа cluster populated arms seen in Sa to Sc systems; some, e.g. NGC 3860, NGC 1268 and 1С 2951 are classed as smooth-arm galaxies, that is objects in which по Population 1 features are to Ье seen.• Clear1y in such cases there is по gas extant to encounter density-waves anа thus form spiral arms of recognisable type, anа star formation wi11 Ье curtai1ed unless the gas сan Ье replenished. The meaпs Ьу which gas сап Ье removed from а ga1axy are: а) ga1axy-ga1axy col1isions; Ь) stripping Ьу interga1actic material апа с) the expulsion of gas Ьу ga1actic winds. Out of these three mechaпisms а) aпd Ь) сап Ье excluded in the context of this volume, but will Ье covered in Volume 5, as the event is most likely to occur in large clusters of galaxies. The galactic wind mechanism operates as follows. Winds are generated in the centra1 bu1ge of the ga1axy Ьу either supernova heating or heating from co1liding she1ls of gas ejected Ьу dying stars. If either of these methods heats the gas to sufficient temperatures, the gas is по longer contained within the centra1 bu1ge of the gal аху , aпd сап Ье driven from both the bu1ge апа the inner regions of the disk. А combination of Ь) anа с) is a1so possible, and in such а aase, опсе gas has been сот­ p1etely stripped from а spira1 it would Ье kept in а gas-free state, aпd по further star formation wou1d Ье possible.

" tica1 and Irregu1ar Ga1axies. "ng оп to the interesting topic of primeva1 ga1axies, Befo re mov~rief1Y take ир the case for the formation of the " "f ~e тust" very 1 nd irregu1ar ga1axles. The formatlon о еасh о f th ese "ptlca а . ' 11 е l 1ies at opposite poles from the splra1 ga1axles. F'or th е types stems the ear1y formation of stars wou1d have Ьееп very E-t~Р~ s~ and anу gas invo1ved soon uti1ised, Ьепсе the current effl Clen ~ of these objects, which are composed of nothing but appear~cstars. In some cases, however, gas is detectable in these o1d, :e and what at first тау Ье considered anoma1istic, the ga1aXl e еs , of young, blue stars. ThlS " t h owever, Ь е 1 ongs 1atter aspec, esen С pr h' h " in the fie1d of interacting ga1axies, w lC wl. 11 Ь е covere d ln

~

Chapter 7. W"th irregu1ar galaxies, objects sti1l forming stars, the ear1y l formation rate was much 1ess efficient, aпd hence 1arge s t ar " amounts of gas are sti11 avai1able for maklng s t ars. ТЬ"lS сап Ь е seen Ьу not оп1у the fair1y chaotic distribution of blue stars and Н 11 regions in these objects, but a1so Ьу the 1arge amounts of neutral hydrogen ( Н 1) in which these ga1axies are embedded. primeva1 Ga1axies. ТЬе possibi1ity that Ьу looking back in time it тау Ье possible to identify ga1axies undergoing а first burst of star formation is intriguing. What has to Ье decided is what the appearance of such ohjects wou1d Ье 1ike aпd whether they wou1d Ье bright enough at large redshifts to Ье observable. Elliptical galaxies of giaпt size, forming stars rapid1~ are cOnSidered to Ье the best caпdidates for prirneva1 ga1axies, ав it is such systems, ав we Ьауе seen, which are very efficient formers of stars. Such objects should Ье detectable i f their brightest state of formation occurs at redshifts of about z = 5, ~З,700 Мрс). For these ga1axies а srna11 angular size is expected to е the case, particular1y if the rate of star formation at its greatest takes p1ace in а region comparable to the nuclei of elliptical galaxies we see at present. For this reason it has Ьееп ~ro~osed that some quasars cou1d Ье primeva1 el1iptical ga1axies. ~lsadvaпtage is that these ga1axies might Ье very dusty objects, eт~ ttin.g most1y in the infrared. Gi уеп а non-dust ridden primeva1 ~~eaxy ~d а given star formation rate, this wou1d have ап absol( 3 smagnltude of about М = -25, aпd at а redshift of about z = 3 i ' 00 Мрс) would have аХ apparent magnitude of about 22 mag, which s а magnitude shared Ьу тапу quasars.

ide~~"i~ now possib1e that numbers of primeva1 ga1axies Ьауе Ьееп lfled which are observab1e as blue objects, some occuring

31

30

Formation and Evolution of Galaxies in clusters of galaxies. However, while it is very likely that the objects are undergoing bursts of star formation, they шау not" оп se the other hand, actually Ье primeva1 ga1axies. Possibly some of th non-variable quasars with suitable spectra шау Ье such objects, е 1ying far away in deep space, and whether or not they are identifi in the near future, the search for them is another ехашр1е of the ed new horizons forever opening ир in extraga1actic astronomy.

'~., ...":. .. ':

,(' ~

- .~",'~'-~:. ~~~ .с"

: ".

~~.

',.

.

..... " ...... ,! .

';О;,

4. GASEOUS AND STELLAR CONTENT OF GALAXIES .

INTRODUCTION , ct evidence that ~s has Ьееn, and sti11 is, present in D~re , сan Ье seen Ьу the presence of stars of a11 types h ауе ор t·lca1 some g alax~es, Ь Н 11 regions. 1n the latter case we аВ we1 1 aS f ~as but not a11 of it radiates at optica1 waveevid ence ~ utrai hydrogen (Н 1), as we11 as other gases and lengthS1· ~an Ье observed оn1у at radio wavelengths. mol ecu es тЬе Н 1 in ga1axies radiates at а wave1ength of 21 сm, and is the fo11owing sequence of events. The ground state, or due to 1еуе1 number 1 consists of two parts, the upper and the energy 1n the 1ow-density regions of Н 1 ln , space, со 11'lSlOnS , lowe:'·frequent between the hydrogen atoms, but when these take are ,u1 Ь е etxcJ.' t е d 'J..n th, е ~pper р1асе at 1ow-speed, the hydrogen atom сап t of energy 1еуе1 1. The e1ectron of the а ош сап rema~n J..n ~~э excited state for ап extreтely 10ng period of time, but wh?n 't eventua11y drops down to the lower part of energy 1еуе1 оnе J..t ~mits а 21-сm photon. Observations of the 21-ст radio emission сan furnish detai1s оп the tota1 mass of Н 1 in а given ga1axy аэ we11 as other data such as rotationa1 тeasures. Distribution of

Figure 9. Two ехаmр1еэ of smooth-arm ~a1axies. Оп the 1eft NGC 3860, оп the right NGC 1268. (~rom St.rom and Strom, 1978. ~eproduced Ьу courtesy of D. Reide1 РиО. Со.).

Н

1 according to Ga1axy

Туре.

1n the previous chapter it was shown that star formation from the primordia1 gas c10uds proceeds most effective1y in those c10uds which ev.entua11y form e11iptica1 ga1axies. As а consequence it is natura1 for such systems to Ье tota11y free of gas. 1n some cases, howev.er, gas is present in E-type systems, e.g. NGC 4472, and spectra show emission-1ines of once-ionized oxygen at а wavelength of 3727 1, thus indicating the presence of gas at very low densities. WЛеn we соте to irregular and spira1 ga1axies we also find ш~сЬ more obv.ious signs of ionized gas in the forт of Н 11 regions.

~:th :ega:d to the Н 1 in spira1s and irregu1ars two types of Н 1

J.strJ.butJ.on occur. 1n the Irr systems, the Н 1 is centra11y ~~ncentrate~ and сan extend we11 beyond the optical boundaries of ese,ga1axJ..es, the 1atter aspect a1so being а feature of 8pira1 ga l aXJ.es.

эЬ Un1ike irregu1ar systems, howev.er, the Н 1 in spiral galaxies it OWS а peak distribution, not at the centre, but we11 away from оГ· At the centre of spira1s, in fact, the Н 1 disp1ays а minimum Ои cOncentration, which gives the impression of а 1arge Ьо1е. In di~tO~ G~1axy, which i8 probably an Sb-type spiral, the annular ~ithrJ.butJ.on of Н 1 1ies we11 away from the centre, as is the case R 11 ext?rnal spirals, and within the centra1 hole are found giant regJ.ons. The presence of optica1 spiral arms within the

33

32

Gaseous and Stellar Content of Galaxies

Gaseous and Stellar Content of Galaxies central hole is not shared Ьу М31, where the Н 1 is seen to Ье со_ incident with the arms. Before continuing with the treatment of hydrogen aпd other gases, we show in Figure 10 the Н 1 distributio n in the irregular Local Group galaxy NGC 6822, in which the very extensive contours of the gas аге clearly shown

[1

ш~:1 ...

;:)

с:

·Е u +

10

~

З

z

О

о

r4-10 z

Ga s

Distribution near Ga1axie8.

---тn cases where neutra~ hydrogen is.de~ectable near galaxies, the tion to Ье answered 18 whether th1S 18 remnant material, 1eft que~ fro m the origina1 gaseous c1oud, or whether it is tida1 in OV~g;n or1 ..., i • е., materia1 drawn out from оnе system Ьу interaction ",ith another. The nearest exaтp1e of the 1atter process is the Magel1anic stream, а loop of Н 1 between the two Mage11anic C10uds aпd possibl) linked to the Ga1axy. There is evidence that this fi1aтent of gas describes virtua11y а 1arge circ1e, and this has Ьееn considered to Ье the product of gravitationa1 interaction between the Sma11 Mage1l anic Cloud and the Ga1axy during а c10se passage (about 20 kpc) something like 5 х 1 О g yr ago. Part of the streaт, incidental1~ is а detached section оnсе thought to Ье an Н 1 companion of the southern sky ga1axy NGC 300. А like1y by-product of such а c10se encounter is that stars тау have Ьееn pu11ed out from the SMC or thE Ga1axy or еуеn both; to date, however, попе have Ьееn observed.

Moving further out past the Loca1 Group, we find other c10uds of Н 1 associated with the IvI81/M82/NGC 3077 trip1et. All three 1ie

--1

~ -20 о

- 30

.

.

-.

\

;

..•.

SЧ:::---~-~:::-------:::'-='--...,-l,---'-~-"-J:'-_~::--"":"'J'-~-1.--J!

- 50 w - 40

- 30

- 20

- 10

О

RIGHT 'ASCENSION

+ 30 (аге minutesJ

+ 40 Е + 50

Figure10. Contours of 21 ст emi88ion 8uperimposed оп а photograph of NGC 6822. (From M.S. Roberts, 1970. Reproduced Ьу courtesy of D. Reidel РиЬ. Co~. Observation8 of the Н 1 content of а galaxy сап aid in deriving such paraтeters as rotation velocities aпd таээ. Тn the саэе of М101 the Н 1 outside of the optica1 boundaries has а mass of about 2.4 х 10~ М , of which about 1.5 х 10 Q М is aS80ciated with the south comp~ion (or Н 11 region) NGC 547~. The ve10cities observed in the 21-ст line agree with the aS8umption that most of the Н 1 is in co-rotation with the optical features of М101. Neutra1 hydrogen is not the on1y gaseous matter connected with 1ate-type ga1axies; other gas, the result of processing in ste1lar interiors, a1so being evident. Aтong the e1ements found are Sodium (S), Calcium (Са), Titaпium (Ti), and 1ron (Fe). Observatio nS at radio wavelengths сап detect molecu1es of water (Н О), Aтmonia (MH~), Forma1dehyde (Н СО), carbon monoxide (СО) aпd ~so far det~ctable in the Ga1axy only - the hydrogen mo1ecu1e (Н ).

2

2

",ithin а common Н 1 enve1ope, and in particu1ar there is а strong bridge of hydrogen between М81 and NGC 3077, which could Ье the resu1t of а c10se passage of the two galaxies. Exaтple8 of Н 1 bridKes are a1so known in more distant ga1axies (NGC 4631 and NGC 4656; NGC 4151 and NGC 4145). А number of ga1axies, e.g. М31, 1С 342, show warps in the outer structure of their Н 1 distribution. The саиэеэ of such features Сап Ъе varied, оnе of the most probable being the presence of an Н 1 companion.• Such an object is si tuated about 60 kpc away fгош the bright SO ga1axy NGC 1023, the ve10city difference between the tvo objects being about 200 km/sec. Мо optica1 feature сап Ье seen :~ the position of the Н 1 object, and аэ other members of the th~ 1023 grOU~ a~e too ~istant to have pu11ed the compani~n from s ga1axy, 1t lS poss1ble that the gas is remnant mater1a1 1eft ОТег from the time the ga1axies formed.

red А: we ЬаУе se~~ e1liptica1 ~a1axies are noted for their old, NGC 1tar popu1at1on, but anoma11es сan exist •. The ЕО system thi {10 lies about 20 kpc away from the SBO ga1axy NGC 1512, and S gen atter object is enveloped in а vast c10ud of neutra1 hydroat ; l~teresting1y, NGC 1510 is quite а Ыие object, comp1ete1y gas ~г~ance with the co1ours of most el1iptica1s. 1f эоте of this this ~ Ъееn accreted Ьу NGC 1510 in the past, it is p08sible that аэ Ьееn enough to form а popu1ation of young, Ыие stars. SUch ро SSl. b 1 ' '" . е 1nteract1ons 1n the rad10 wave1engths a1so d1Sp1ay

34

Gaseous

апа

optical features in some cases, anа these, as well as further excursions into re1evant radio observations wi11 form part of the substance of Chapter 7. Stellar Distribution in Galaxies. The colours of galaxies show characteristic features: E-types _ red; spirals - red centres anа Ыие disks, anа irregulars - Ыие. Leaving aside emission~lines in normal galaxies, which arise in Н 11 regions, the spectra of galaxies will display absorption lines anа in the very nearest systems the spectra of individual stars I (anа clusters) сan Ъе obtained. 1n more distant objects, however, information about their stellar content сan only Ье derived from integrated spectra. The composite spectral features in far-off galaxies give data the their stellar populatiDns. То take two examples, low-density dwarfs have stellar populations similar to metal-poor globular clusters while high-density giants show spectra with super-metalrich characteristics, that is, they contain large numbers of giant stars with а heavy metal content. То take every absorption feature separately is not our purpose, but we сan give brief details of individual features anа their саиэе, аэ а given absorption line or Ьanа will relate to а certain type of star. Thus cyanogen (CN) Ьanаэ near 4220 and 3880 i are indicative of the presence of G5 to К4 giant stars; the magnesium (Mg) Ьanа near 4800 К теanэ that К to МО dwarfs are present anа the strong titanium oxide (TiO) Ьапаэ in the red anа infrared refer to а population of Mira-type stars. оп

А

5. NUCLE1 OF GALAX1ES

Stellar Contenx of Galaxies

large percentage of stars of а given type аоеэ not шеan that the total luminosity which they radiate will also Ье large. This сan Ье demonstrated Ьу taking just the nucleus of М31, the light of which is таае ир Ьу about 17 different types of stars. 1n this galaxy's nucleus the greatest percentage of light (18.2%) is аие to super-metal-rich stars of K2111-1V. The percentage of the total mas s of the nucleus contributed Ьу these stars is, however, only about 0.03%. 1n contrast, М8У stars contribute only 0.5% of the nuclear luminosity but 66.92% of the total шаээ.

INTRODUCTION. In speaking of nuclei it is necessary to define exactly what is t Ьу this term. Often the words 'nuclei' or 'nucleus' are иэеа me~enote the central regi~ns of galax~es, ~a such regions. should tOt Ье confused with nuclel proper, WhlCh dlsplay angular Slzes по .deraыy 1ess than central regions or bulges. со пsl

Almo st all galaxies of intermedi~te and.high luminosity эеет . ossess nuc1ei; exceptions are obJects 1lke the Smal1 Magel1anl tO Pd and the Scu1ptor dwarf galaxy. Other systems at greater C~O~ sees than the аЬоуе two examples тау show по discernable dlS1~ at low resolution, but higher resolution photography тау пис el . эьоу very sma11 nuelel. ТЬе question of resolution is an apt опе in this context. It is probablY not a1ways realised that the nu~leus ho f eYbe~ а large , t nearby ga1axy is of very small angu1ar Slze. Т е о VlOUS sys.em to quote in this regard is М31, whose nue1eus has an appa~en1t s~ze o~ about 2.8 х 1.6 arcseconds, whieh eorresponds to an ас иа Slze о 9.4 х 5.4 ре at а distance of 690 kpc. The further away we 1ook, therefore, the smaller appear galaetie nue1ei; for М81 the apparent size of the nuc1eus is already redueed to 1e~s than опе areseeond while for spira1s at the distance of the Vlrgo c1uster of ga1axi;s the nuc1ei are 1ess than 0.1 arcseconds in angular size. То get the best idea of the intrinsic diameters of the nuc1ei of spiral ga1axies is to realise that these are matehed Ьу эоте galaetie globu1ar c1usters, about 10 ре. Туреэ

of Nue1ei.

ТЬе two main types of nuelei are the passive anа the aetive •. ThE former is self-explanatory in that по unusua1 parameters are eVld~I

vhile in the latter various eharacteristics are in evidence, ranglI from violent motions of gas c10uds (detected spectroseopically) to bright condensations and variations in luminosity (detected optical1y). Basica11y an active nucleus is опе in which а percenta~ of the observed radiation appears to Ъе the result of non-therma1 radiation, а topic which wi11 Ье CDnsidered further.i~ the next chapter,with regard to extreme forms of nuclear actlvlty. Among the nearest galaxies with active nuclei are N~C 253, NGC 4258 and NGC 4'7з6 The former eontains а powerfu1 lnfrared • . .t uc1e1j SOurce, while the latter has an intense radio feature ln 1 s n NGC 4258 is noted for its anomalous spiral arms, which are tho~ght hy воте to Ье due to the high-speed ejection of materia1 from ltS nucleus.

36

37

Nuc1ei of Ga1axies. The 1arge infrared 1urninosities of ga1axies 1ike NGC 253 are ~иe to non-therrn~l s?urces operating; if stars accounted for the ~nfrared flux wh~ch ~B observed, they would пееа to Ье hi h 1 " "t у О апd В s t ars, objects with lifetirnes of only about g urn~поз~ 106 yr, ап extrernely sma11 percent ge of а galaxy'·s lifetirne Als о :Ln .. " , • тапу сазез the ~nfrared lurn~nosities of galaxies are greater th the optical lurninosities, and exarnples of such objects аге an NGC 4151 and NGC 52з6 (М83). The former of these is а Seyfert. galaxy, апа these ohjects will Ье taken ир in the next chapter. Аз we11 аз dust, which is necessary for infrared emission, the nuclei of ga1axies also contain gas; emission 1ines denote the presence of low-density gas, aпd often srnal1 radio sources аге to Ье found in emission-1ine nuc1ei. Nualear emission-1ines Oc~ur more often in radio-nuc1eus systerns, anа at present this aspect is not understood; either the nuclear gas was present before the onset of radio ernission ог, a1ternative1y, the ernergence of the radio source coincides with the арреагапсе of the gas. А type of nuc1eus of interest is the Hot-spot nuc1eus, which display bright, small regions. Al though по correlation exists hetween these nuc1ei aпd radio sourc~s, activity is possible iп galaxies harbouring them. Опе Hot-spot galaxy, NGC 1808, shows spectroscopic characteristics which have Ьееп interpreted as being due to material ejected frorn the nucleus a10ng the rninor axis of the galaxy.

Iп conclusion, mention rnust Ье made of the c1assification of ga1actic nuc1ei c.arried out at Byurakaп.Observatory. In this survey the centra1 parts of a1most 500 ga1axies 'йеге studied, anа these 'йеге fina11y divided into the fo11owing groups. C1ass 5: prominent star-1ike nuc1ei; C1ass 4: star-1ike nuc1ei not уегу distinct ог pronounced; C1ass 3: genera1 increase in brightness to the centre where по ste11ar nuc1eus is visible; C1ass 2: а notable increase of brightness to the aentre which has somewhat pecu1iar irregu1arities in ~rightness distribution; C1ass 1: по brightness increase to the centre and, fina11y C1ass +2: Ga1axies with nuc1ei sp1it into two parts.

6. SEYFERT GALAXIES, QSO's AND RELATED OBJECTS !1~TRODUCTION th'S chapter 'йе sha11 consider the pararneters that 1ink the Тп t ~alaxies, QSO's апа BL Lac objects. A1so inc1uded in the seyf er of the chapter wi11 b~ radio ga1axies, aпd 'йе sha11 define ts conte~operties which distinguish radio ga1axies from those other the t Pтз that erni.t radiation at radio wave1engths. Аз wi11 Ье зееп., sYS explanations for the energy sources of radio ga1axies, QSO's the eseyfert galaxies are соттоп to a11. Both optica1 апа radio s~ffi~acteristics of these active systems wi1l Ье cDvered, but we ~a: do по more than skirn the surface of what is а cornp1ex subject. !!!di о Gal axi е s • Since the first discovery of radio ernission from ga1axies in' 1949, it has Ьееп found that тапу ga1axies, inc1uding our оwn, аге radio emitters. In the case of most spira1s а srnal1 radio f1ux is pres ent • Such ga1axies as these are c1assed аз weak radio зоигсез, but when 'йе соте to the strong radio ga1axies, not on1y is the emitted f1ux much greater, but the source objects are al1 E-type systems~ These сап Ье divided into the fo11owing: а) C1assica1 E-types (М87); Ь) D-ga1axies (simi1ar to а) but for the presence of а large, faint enve1ope); с) N-ga1axies aпd а) Dumb-be11 galaxies, showing аоиЫе nuc1ei. The abso1ute magnitudes of radio ga1axies are very high, of the order of -20.5, thus making thern among the optica1ly brightest extraga1actic objects. A1so of 1arge intrinsic size are the angu1ar sizes, particu1ar1y if 'йе inc1ude the detectable 1imits of the radio emission. .It wi11 Ье reca11ed from Chapter 4 that the Н 1 distribution in s~~ra1 апа irregu1ar galaxies extends beyond the optica11y deter-

m~ned boundaries, апа а simi1ar situation prevai1s in radio ga1a-

~~es, w~ere ~he radio-ernitting materia1 is present we11 outside e ~pt~ca1 ~rnage. However, in radio ga1axies the phrase 'we11 ои t S:Lde' g' , Fu t ~Уез по ~aea of the vast extent of the radio sources. s r hermore, these аге not distributed symmetrica11y around the T;;~ce ga1axies, but a1igned оп each side of the visible ga1axy di~c~llY these radio lobes аге separated Ьу а few times their • to ое eг~, the emitting regions being of а size about two thirds mUChne~f~fth of their separation, a1though some, e.g. 3С 33 appear W:Lder • Th е d ои Ы е па t ure о f ' [о г 11 the rad~o lobes appears to ' exist 20 k; SOurces where the intrinsic diarneter is greater than about tical~· If 'йе rea1ise that the linear diameters of giant e11ipintrin ~an ?е 50 kpc, and that the 1argest radio sources Ьауе then ss~c d~ameters over ten tirnes that of the associated ga1axy Оше idea о f th" ' e~r ех t ent сап Ье gauged. Nothing rea11y

39

38

Seyfert Galaxies, QSO's and Related Objects

Seyfert Galaxies, QSO's and Related Objects succeeds like an il1ustration, however, and in Figure 11 is shown the distribution of the radio emission around NGC 5128 (Сеn А). А а further ~oint of intere~t thi~ g~laxy a1so disp1ays а secondaryS double radlO source contalned w~thln the optica1 iтage, and this i a1so shown in the figure. S CENTAURUS Nr,C

-:

А

~r2B

Synchro tron rad~ation occu s when аn e1e~tron, movin~ at,a 7 lativistic ve1oclty, сотев lnto contact wlth а тagnetlc fleld r: is a1igned in the direction of the e1ectron's trajectory. ich ;роп contact, the e1ectron spirals around the тagnetic fie1d line, and as it does so emits radiation in а smal1 сопе. Thus, ав the radiation vector sweeps round, it is detected Ьу the observer as а pulse. The diagram in Figure 12 shows this action.

:.

•

these regions that the energy sourc~s тust lie. An ideal it iS.i~ point is the giant el1iptica1 ga1axy М87, which d~splays star~l~ of materia1 extending out from the centre. These Jets are t~O Je ~ at optica1 wave1engths, and spectroscopy of the brighter a.ppax~nws а feature1ess continuuт; phot.ographs, however, revea1 oneU:b~r of structure1ess knots, with 1inear sizes of about 20 kpc. а. n light from this jet is partia11y po1arised, and this, p1us the Thetinuous spectrum, indicates that the radiation producing the соn feature is synchro t ron ra d'la t'lOn.

~4

." .... : ...... ."

,:".1. 'I':~:':,~,' ."" ."

.

~

~

•...

~

".. ':..

.",!,

...

.

Spiralling Electron

I'~.

•

'

--Magnetic Field Line

"

• . :"

.---т_

'\

...... *

.

,"

~.

, • 10 "

/

крс

'

Figure 11. NGC 5128 (Сеn А). The extent of the radio eтission is shown оп the right extending froт а photograph of the ga1axy. А 1arger sca1e photograph of the ga1axy is at bottom 1eft with the position of the secondary double radio source тarked. The top 1eft positive photograph shows the we11-known absorption feature. (Reprinted courtesy of A1an Т. Moffet and The Astrophysica1 Journa1, published Ьу the University of Chicago Press; © 1975 The Aтerica1 Astronomica1 SocietyJ, NGC 5128 is а prime object of study as it is the nearest radio ga1axy, and hence very iтportant in investigations of these objec ts , and at the heart of these observations 1ies the probleт of determining the тechanisms which give rise to the radio emission. Physica1 Processes giving rise to Radio Eтission. Here we are back оnсе тore in the rea1ms of ga1actic nuc1ei,

aS

<'

, ---, ,, '"'" '" , '"

Figure 1 2. Diagram of Synchrotron Radiation Process.

-::'' ' 1'

Веат of Radiation

We have вееn that the 1ight froт synchrotron radiation is

P~larised, and in typica1 radio ga1axies the po1arisation decreases

w~th increasin€ wavelength r

Apart from М87, another well-known f~laxy emitting polarised radiation is М82. Originally this was f ought to Ье an exploding system, but later the idea was put f~rward that the cause of the polarisation and optically-observed In ~ents was due to interaction with an intergalactic dust cloud. gal ~ fO~lo~ing chapter we shall again return to the subject of Whia~les l~ lnterac~ion with clouds of intergalactic material, in с mentlon will again Ье made of NGC 5128.

lar~at triggers the activity in radio galaxies? It now appears tha' occu;.amo~nts of energy are released in one or more violent events lng ln the nuc1ei of these galaxies, and that this is sub-

41

40

Seyfert Galaxies, QSO's and Related Objects.

Seyfert Galaxies, QSO's and Related Objects sequently flung out from the nucleus in opposing directions. Theori as t~ the triggering mechanism.are: а) ~ QSO is.the perpetrator; ь)е: mult1ple supernova event, caus1ng а cha1n react10n with other stars. с) gravitationa1 co11apse of an object or objects; d) fo11owing оп ' from the supernova theory, that а number of pu1sars are the cause е) accretio~ of.materia1 оп to а black.ho1e. Out of these, the su~e~d nоуа mechan1sm lS somewhat out of fash1on, for, whi1e the energy emitted Ьу а typica1 supernova is about 1051 ergs, тanу such events are needed to occur within about 10~ yr to provide the necessary energy. It is therefore obvious from the аЬоуе that an active nuc1eus is at the root of the radio emission, so we sha11 now pass оп to very obvious manifestations of active nuc1ei - Seyfert ga1axies, QSO's and the В1 1a~ objects. Seyfert Ga1axies. Radio emission is detectable in Seyfert ga1axies, but in most cases it is of weak intensity, and on1y а few are strong sources such as 3С 120 (BW Tau) which was discovered to Ье а ga1axy Ьу its radio emission. Аэ сan Ье seen, it was оnсе c1assified as а variable star. Of the strong radio Seyferts, it is main1y Seyfert 2 objects that соте into this category, and the radio emission appears to Ье linked with the emission-lines seen in the spectra of Seyfert nuc1ei. Forbidden 1ines in spectra are the result of transitions occuring in very low density gas, as was exp1ained in Vo1ume 3 of this series, and in Seyfert ga1axies forbidden 1ines of Iron, Oxygen, Argon and other elements are to Ье found. With regard to the permitted 1ines of Hydrogen seen in Seyfert spectra, these furnish information оп the interna1 motions of the gas in the nuc1ei. The widths of these lines in both classes of Seyferts indicate the fo1lowing velocities: in the Seyfert 1 c1ass gas ve10cities extend ир to 18,000 krn/sec whi1e in c1ass 2 Seyferts the 1ines indicate ve10cities of around 500 krn/s ec • Оnсе gas exceeds а given ve10city it сап еБсаре from the parent. ga1axy, and the 1imiting ve10city сan Ье quite 10w compared with the above-mentioned figures, on1y about 1000 krn/sec. The mass 10ss in NGC 4151, due to gas ejection, has Ьееn ca1culated at up to 10,000 М yr. At lower ve10cities than 1000 krn/sec, ejected gas would fall b~ck into its ga1axy, and such аn occurence seems to taking place in our own Ga1axy. Our Ga1axy, therefore, has an active source in its nucleus, but this is, of course, nothing 1ike the energy sources in Seyferts. Gravitationa1 activity сan Ье very energetic, as is shown for сав е е) at the top of this page, which has Ьееn used to explain the . lе energy source in the nuc1eus of NGC 5128. Accretion is also а posSlb explanation of Seyfert nuclear activity, and оп а grand scale. ТЬе

accretion о! material оп to а very large mass black h о 1 е or а very sizeable nurn Ь er о f neutron stars cou1d account for th е energy out. flo w from Seyfe:t nucle1. ~s а comparison object we сan take the crab nebula, Wh1Ch has an 1ntrinsic size and radiation ch t · h ld Ь arac eristics wh 1C сои е very . similar to Seyfert nucle1' • Th е d'ff 1 erence between the two, however, lS in the arnount of energy given off, which in а Seyfert nucleus aould Ье as much as 107 times that of th е С ra. Ь ~asi-Ste11ar Objects. The first QSO was identified in 1960 (3С 48) and was optical1 to.be а Ыие, 16 mag ste11ar object with faint associated у nebu1os1ty. In the саэе of.3C 27~ there are two distinct optical features, а ste11ar body w1th а Jet of materia1 nearby. Whi1e воше QSO's are radio emitters, others are radio quiet· in a11 са h ' ses, however, t еу appear to have extreme1y high 1uminosities, of the order of 105 that of norma1 ga1axies, and this, plus other characteristics, made them initia11y regarded as highly unusua1 objects Since then it has Ьееn found that the spectra of the nearer (l~w redsh~ft) QSO's are very similar to the spectra of strong radio gal~les and Sey~erts! and that the spectra of the more distant QSO's are 1n fact cont1nuat1ons of such spectra into the ultraviolet. The current exp1anation of QSO's is that they are the excessive1y active nuclei of ga1axies,

вееn

?

.In Chapter it.was suggested that some QSO's тау in fact Ье ga1ax1es 1n ear1y bursts of star formation. What evidence 18 there that QSO's are ga1axies, bearing in mind their unusua1 ~roperties? Very distant ga1axies, in c1usters for exarnp1e disp1ay ~шаgеs th~t are virtua11y ste11ar, and а 1arge percentage ~f QSO's o11ow th1S exarnp1e. Exarnp1es do exist, however, of QSO's in which other materia1 сan Ье seen. PKS 0837-12 exhibits outer nebu10sity of average ga1axy size and shape, whi1e Топ 256 is surrounded Ьу an elliptica1 ga1axy; both this and the bright QSO centre have the эате redshift. ~r1шеvа1

.А feature of the spectra of QSO's is that both absorption and

еШlssiоn th

l'1nes are presen,t , the former being 1ess redshifted than m e l~tter. Two exp1anations сan account for this' either the а t er1a1. res ~ons1. . b1 е f or.th е а Ь sorpt1on " '. . QSo lS connected w1th а glven ga or 1t ar1ses 1n mater1a1 connected with intervening ga1axies or iss~~uS c10uds. At the present time it seems that the 1atter саэе the е most 1ike1y, and this wou1d, о! course, nice1y account for redshift difference between the two spectra1 features. 'l'he . l'1nes, оп the other hand, occur within QSO's, and are' ет'lSSlOn 80ur1n а11 probabi1ity due to nearby gas surrounding the power Се, which is thought to Ье gaseous matter entering а massive

42 43

Seyfert

Ga~axies,

QSO's and Related Objects.

black hole, the origin оГ the gas being possibly due to а range ог occurences including material Гтот stellar collisions and stars whi Ь have Ьееп totally disrupted Ьу tidal forces produced Ьу а black hOl~ The origin оГ а black hole сan Ье due to а wide variety оГ prior • events including supermassive stars and dense star clusters. 1n the latter case clusters of stars of 100 М@ could eventually form giVing rise to multiple supernova explosions which will produce а cluster ОГ neutron stars от black holes. Whatever form their evolutionary sequences take, black holes represent extremely hi~h power sources, producing the vast amounts of energy which епаЫе QSO's to Ье detected at such great distances. BL Lac Objects.

With these objects we ате still concerned with sources of small angular diameter and high luminosity. The prototype of these galaxies was опсе considered to Ье а variable star, BL La~, and it is only comparatively recently that its extragalactic origin has Ьееп recognised. А similar object, АР Lib, was also originally catalogued as а variable star. Other BL Lac objects have Ьееп discovered quite recently, while similar objects with lower luminosities include В2 1652+39, В2 1101+38 and NGC 6454. 1n the cases of OJ 287 and 0735+178 по galactic envelopes ате observable, but these ате to Ье found in BL Lac and АР Lib. These outer envelopes ате faint. wi th regard to the central regions оГ these galaxies, and show absorption lines in their spectra which ате quite typical оГ those in normal giant galaxies, and in essence BL Lac.is. ап elliptical galaxy wi th а nucleus displaying certain character~s~lcs. The properties оГ BL Lac objects, от rather the strong central regl onS , consist of nonthermal radiation, rapid variability, strong and variable polarisation and infrared emission. Unlike the QSO's, the nuclei оГ BL Lac objects display по emission lines, although in а few cases some уету faint ones ате likely. The cause of the lack of . emission lines is thought to Ье due to radio frequency heating, wh~ch с2Л give rise to hot сотопае around emission-line clouds, and in. extreme conditions this сan blot out emission lines. BL Lac objects, therefore, ате best considered as а variant of the QSO's, as in both types оГ object the dominant feature is nonthermal radiation.

7. 1NTERACT1NG AND PECUL1AR GALAX1ES INTRODUCT10N We have lumped these two ~lasses of galaxies together due to the fact that тапу interlact~~~ gat~aXies display peculiarities, and as а uence cross с aSSl~lca lOn occurs in тanу instances. c.o ns eq The definition оГ interacting galaxies is self-evident, but it .~s necessary . to define just what constitutes а peculiar galaxy, аэ ·t is poss~ble, but wrong, to regard them аэ пеу galaxy types. 1n ~he large majority of cases, peculiar galaxies ате objects showing unusua1 structure but which still fall within the НиЬЫе от the de Vaucouleurs classification scheme. Objects outside the basic galaxy types ате those like ring galaxies, although it арреатв that еуеп these опсе posessed а НиЬЫе type; ring systems are also good examples of objects which ате both interacting and peculiar. 1n Chapter 1 ,"е showed the classes into which Атр has divided peculiar galaxies, and at this point it is necessary to define the various classes into which Vorontsov-Velyaminov has divided interacting galaxies. The definition of these galaxies, as given Ьу Vorontsov-Velyaminov is: а) Systems where regular shapes ате perturbed as а result оГ interaction with another another galaxy and Ь) Systems where galaxies ате embedded in а comтon luminous ' haze. Such.obje~ts ~aye.been grouped into 10 categories, ranging from ~ecullar dlstrlbutlon of Н 11 regions to disrupting nests of galaxles, M51-type systems and chains of galaxies. .From.here оп уе shall detail examples оГ а few selected objects Whlch flt the title given to this chapter. The obvious method is t~ use bright, well-known. objects for some of these examples and Slnce such objects ате not too соттоп among пеатЬу galaxies 'they are naturally seized ироп when they ате relatively close In the СОитэе о! th' h • NGC 40 8/ lS С apter, therefore, уе shall mention М51, NGC 5128, f .3 9 plus other, less well-known objects Ав' а prelude а еу llnes will Ь t k Ь' • , whi h е а еп ир у а brlef survey of the processes с produce the observed structures. Both Тоотте and V t V 1 . and ln . t eractin t oron f sov- е yamlnov, who have studied peculiar more ОГ .g sys ems от тanу years, have estimated that 15% от eXist galaxles have suffered mergers or collisions during their formaet~ce. Collision or interaction сan. result in bursts оГ star lOI1 and о! which' as examples we сan take NGC 2623 and NGC 7252 both Which seem. to show evidence оГ large bursts оГ star formation provid~ccu7ed а few hundred million yr ago. М82 and NGC 5128 also it eVldence f . t is not or ongolng s ат formation, but in the former case Page 39. а case о! galaxy-galaxy interaction, as mentioned оп After а period

оГ star formation has occured due to interaction

44

45

Interacting and Peculiar Galaxies

Interacting and Peculiar Galaxies the respective galaxies should eventually appear as ordinary-lookin systems with regard to color and structure. This implies that many g objects currently appearing normal could have undergone large-Scale disturbances during past epochs. We shall now consider individual objects, beginning with NGC 5128, which has already Ьееп alloted а degree of space, but which displays characteristics not yet covered, NGC 5128. The radio properties of this object have already Ьееп broadly sketched in, anа here we shall concentrate ироп the optical aspects, Figure 13 shows in more detail than Figure 10 the photographic appearance of NGC 5128. Noted as being а striking object in the NGC the galaxy was опсе thought to Ье the result of а collision between' two systems, but for а time this idea fell out of favour, only to Ье resurrec~ed again later.

Figure 13. NGC 5128 taken in ultraviolet light Ьу Dufour with the CTIO 4-т telescope. (From уan аеп Bergh, 1978. Reproаисеа Ьу courtesy of D. Reidel РиЬ. Со.).

the photograph oppositr we see

а

main, luminous body, like

~nof а normal giant elliptical galaxy. This i8 bifurcated Ьу а

tb a of dark material, which is interpreted in terms of а ring or d b~k of dusty material. The elliptical component contributes 9~~ the light, anа is composed of old, red stars. However, old as Оь, component is, active star formation is visible along the edges tf~~he obscuring band as well as behind it. In Figure 12, note in о rticular the distribution of the young stars below the dark ~:terial anа towards the lower part of the photograph. While young, Ыие stars and clusters populate both edges of the dust band, other stars are reddened due to the heavy absorption produced Ьу the dust.

d}

Such features тау Ье the result of the merging of an intergalactic gaseous cloud, or а small galaxy, with а giant elliptical system about 10 Q yr ago. As we have seen, however, uncertainties exist regarding the presence of intergalactic material, so it is quite possible that а galaxy-ga1axy interaction is responsible for the observed features. А further fact relative to this is that а moderate аЬипаanсе of metals are found in the dust Ьanа, anа as the most likely explanation of this is prior processing in а galaxy, this reinforces the two-galaxy merger idea. А percentage of the dust must fall оп to the elliptical galaxy, and almost twenty years ago, Schlovskii theorised that violent nuclear activity тау result from the penetration Ьу infalling material of а galactic nucleus, an accretion process which has already Ьееп mentioned with regard to active nuclei, with the added requirement of а black hole. Finally, another peculiar object тау Ье an example of а similar occurence, NGC 2685 (Arp Зз6).

NGC 5194-5, 1':151. Objects of this type appear to Ье fairly соттоп, тапу examples being found in the photographic atlases of Arp and Vorontsov~elyaminov. There is по doubt that with the example of М51 we ~e two galaxies to consider. In the photographs of this ohject w .ch are normally seen, по real structural peculiarities are in ~Vl~~nce. Different use of photographic material, however, сап bring p~ l~ht very different morphology~ as is shown оп the following e .ln F~gure This photograph has Ьееп made ир from а print о! ha.s lb n WhlCh the normal appearance of the galaxies (white images) ' 111 Jееп s uperlmposed ироп the result of five deeply-exposed twoa-l photographic plates (dark images). In particular, note the l'egi P umes or streamers (А and В in the figure) extendiI'l.g from the оп of the ~maller galaxy. Recent d Ь аУе Ь то els Ьу Alar Toomre, using computer test disk particles, een galaxi constructed to try to duplicate structure in interacting es, and Figure 15 shows these results for the М51 doublet.

Msf

14.

46

47

Inxeracting and Peculiar Galaxies

1nteracting and Peculiar Galaxies

~~~O" 1

,

2

$pn

I

-1

рее,

о

Figure 14. Composite photograph of М51 Ьу Burkhead. (From Toomre, 1978. Reproduced Ьу courtesy of п. Reidel Pub. Со.). 1n Figure 15, the left-hand views are аэ эееn from the Sun and the right-hand views аэ эееn from the west, both of them clearly showing how the plumes or streamers are associated with the small galaxy as а result of the interaction. NGC

1 ,

.;

~.038-9.

1п 1977 Toomre presented eleven examples of NGC galaxies which were considered to b€ merging systems; heading the list was the NGC 4038-9 pair.

1n the late 1960's, these two objects were regarded as representing а single, exploding galaxy, but the identification of them as tио systems in. interaction is now certain. Recent observations Ьу Schweizer show extensive tails, which are 20 arcminutes from end to end. UBV photometry shows that the tails are composed of stars similar to those found in late-type spirals, and with ages much younger than the determined time of interaction •. Аэ а resul t of these observations it is concluded that the tails were formed from material pulled from the two galaxies. 1n addition, at the tip of the southern tail is а stellar system о! very low surface brightn.ess which is composed of young, blue stars .. bluer than in the average irregular galaxy. 1t thus appears that dwarf irregular galaxies сan Ье created out of tidal interactions between two

2

N

1

Sun--1

Figure 15. Model of the tidal encounter in М51. (From Toomre, 1979. Reproduced Ьу courtesy of п. Reidel Pub. Со.).

48

49

Interacting and Peculiar Galaxies.

Interacting and Peculiar Galaxies.

large systems. Further partl'cle tests Ьу т oomre s h ow th е process the interaction well, while the optical structure is well-seen inO f Schweizer's photographs, two of which are shown in Figure 16.

.

.

.

.

'

..

• • • Jj

~

8 ••

.•... . 1" .

. ".

•

•

.,..

•

• .-

.......

• :: . .'! • • •

. .'

~.:

"

"

..

~

, ',';.

.

',.

Figure 16. NGC 4038-9 photographed Ьу Schweizer with the C~IO 4-т telescope. The left-hand photograph is of 50 mlnutes exposure, the right-hand опе а superimposition of two plates totalling 3.5 hours exposure time. 1п the latter the dwarf system mentioned above is arrowed. (From Schweizer, 1977. Reproduced Ьу courtesy of D. Reidel РиЬ. Со.).

ted Ьу а ring of stars anа emission regions within which is set leus which· appears offset from the centre of the ring. Fainter а nuc'al is also visible inhabiting the space between ring anа sna ter1 nucl eus • Ring galaxies such as these are not соттоп in the sky, and only а have Ьееп studied thoroughly; of these, АО035 ('The Cartwheel') ~ 11 Hz 4 are the best known~ and it was the latter object which first utilised Ьу Toomre anа Lynds to explain the unusual ~~в cture displayed Ьу these galaxies. The method of formation is s ~ollows. А large, spiral galaxy is penetrated Ьу а smaller galaxy a~ich раээеэ through the plane of the larger. Аэ the intruding system ~ ввев through, the extra gravitational attraction саиэеэ gas in the ~~sk of the larger system to move towards its centre. At а given time tbis gravitational attraction will сеаэе, аие to the emergence of the smaller galaxy. At this point the inwardly-moving gas in the large system will spring back violently, giving rise to an outward-moving density wave, which triggers star formation. Eventually а ring is formed which is таае ир of О anа В stars anа associated Н 11 regions vhile remnants of the original disk material, falling back towards the centre of the larger galaxy, тау Ье aligned in an arrangement like wheeel spokes, аие to differential rotation. This latter type of structure is most prominent in АО035. Finally it is expected that tbe smaller, intruder galaxy will Ье swept free of its gas ьу the encounter, anа such а small, gas-free system is evident near АО035, ав depicted in Figure 17. .

ln а

Figure 1~. АО035 taken Ьу Blanco with the СТ10 4-т telescope. The gas-free intruder galaxy is indicated ьу an arrow. (From Toomre, 1979. Reproduced ьу courtesy of D. Reidel

Ring Galaxies. With these objects we are still in the realms of galaxy interactions, although the results produce different structures from the examples enumerated above. First, however, it is necessary to define ring galaxies. There are тanу examples of systems displaying various degrees of ring st::-uc:ture; these range from objects wi th small, inner ring form~tlDns (NGC 1343~ NGC 3310) through systems with rings of apparent' ~ gaseous materlal away from their centres (М101 IC 10) to ring~ llke structu . , , res sееmlлg to result, аэ Vorontsov-Velyaminov has t s ressed frош а Spl' h curv ь' . ra 1 ~rm wh'l~.~. эееп from earth, appears to е ack anа glve the lmpresslon of а ring. Such Objects are not true ring galaxies,

аэ the latter are ao~~

РиЬ. Со.).

•

51

50

8. CATALOGUES OF GALAXIES.

Interacting and Peculiar Galaxies. Models о! ring galaxies have also Ьееп constructed Ьу Toomre. Не has shown examples о! six penetrations о! а disk о! 2000 test part icles Ъу an intruder particle, and опе о! these displays а marked similarity to АО035, as Figure 18 shows.

о

I

о

о

Figure 18. Vertical penetration о! а disk о! 2000 test particles. (From Тоошге, 1979. Reproduced Ъу courtesy of D. Reidel РиЪ... Со.).

1t is уегу likely that tidal effects do not account for all о! the observed connections between galaxies, and that in эоше cases we are observing galaxies in varying degrees of fragmentation. This idea originated оуег twenty years ago, and its cDnceiver, Ambartsumian, believes that the splitting of а nucleus lies at the heart of the fragmentation process. А large number of objects in which Vorontsov-Velyaminov considers dispersion to Ъе likely аге presented in Part 11 of his Atlas of 1nteracting Galaxies (1977). Currently, preliminary observations are being carried out in order to study the relative motions of the components of chains and nests of galaxies. Finally it must Ье realised that in тапу cases we тау stil1 Ье а long way from understanding the activities occurring in pecu1iar and interacting ga1axies. 1п the introduction to his Atlas, Arp stresses this point, and remarks that ga1axies аге more than amalgams of stars, radiation and gravitation. Не stresses that the importance of dust is obvious in certain of his peculiar system S , аэ we11 as the apparent action of magnetic forces, ап aspect which is not easy to study but тау Ье of great importance. Ву further studies it is to Ье hoped that at least some indication of the . 1 processes ho1ding sway in these often strange-looking objects w11 Ье forthcoming.

1t is not too great ап exaggeration to say that the catalogues and is ts of galaxies now extant seems almost as endless as the objects l' which they are concerned. Overlaps, however, do occur, as we have th _1 n for compact and Seyfert galaxies and peculiar and interacting se: tems • 1п this chapter we shall not Ье concerned with the ga1axy list ~y the Atlas Coe1i catalogue, but will briefly cover а selection of the lnblications in the professional field. The Coeli list is very useful i~ ата teurs, and covers all the bright, plus а nUJ':1ner of fainter objects. Where professiona1 sources often score over Coeli is from the point of view of additional data оп individua1 objects p1us references for further research. ТЬе basis of present day catalogues is the Shap1ey-Ames 1ist of over 1000 galaxies to 12.8 mag (1932, Harv. Апп. Vo1. 88, No. 2). А revised edition is now being prepared, whi1e ап extension of it is the Revised Cata10gue of Bright Ga1axies Ьу de Vaucou1eurs (1976, University of Техаз, Austin). This is а very detai1ed work, giving тапу references, 1ists of radio sources and sources of photographs. In passing it is necessary to state that по cata10gue is 100% comp1ete to its quoted 1imiting magnitude, and for the RCBG the comp1eteness is 98% to 11.5 mag and 50% comp1ete to 12.5 mag.

Sma11er in conception, but very usefu1, is the Uppsa1a Cata10gue of Ga1axies (Ni1sen, 1973), but if we wish to study а much more comprehensive pub1ication we must turn to the Morpho1ogica1 Cata10gue о! Ga1axies (Vorontsov-Ve1yaminov et а1" 5 vo1s, 1962-8) and the Cata10gue of Ga1axies and C1usters of Ga1axies (Zwicky et a1, 6 vo1s, 1961-68, Ca1if. Inst. of Techno1ogy, Pasadena). In both these the 1imiting magnitude is ~5.5 mag, whi1e the former inc1udes charts of t~e regions p10tted from 48-inch Scmidt p1ates. Whi1e magnitudes are glven, angu1ar diameters are not, un1ike the MCG, which gives inner and outer diameters. Regarding photographic at1ases and associated cata10gues there is

:h~t of Ho1mberg (1937, Апп. Lund ОЬэ. No. 6) comprising 827 double n

ga1axies down to 16 mag and covering 52% of the sky. In . has Ьееп found that а number of the sma11er objects lt stars, but the work is sti11 а usefu1 reference point. pr~ ~rigina1 edition of Arp's At1as of Pecu1iar Ga1axies is out of cannb' a1th~ugh а new опе is being prepared. However, sma11er copies (1966е obtalned very cheap1y from the University of Chicago Press, О! I Ap.J. Supp. No. 123, Vo1. XIV). A1so very usefu1 is the At1as Aatr~ ~racting Ga1axies (Vorontsov-Ve1yaminov, 1977, Astron. & аа wei1 Ys . Supp. Vo1. 28, No.I), which contains very detai1ed notes ~ade f аэ а wide variety of photographs. Fina11y mention needs to Ье ident~f.the.Pa1omar Sky Survey prints, which are extreme1y usefu1 аэ print~ lcatlon checks. Detai1s of prices plus а cata10gue of the сап Ье obtained from Ca1ifornia Institute of Techno1ogy Bookmu1tip1e r уе inecent 1 ars С ТЬ uded are

t

52

53

Cata10gues of Ga1axies. store, Pasadena, Ca1ifornia, 91109). The 5-уо1ите Cata10gue of аа1ах' and C1usters of Ga1axies (саса), Zwicky et а1, сап a1so Ье obtained 1. е э from ~he Ca1tech bookst~re, whi1e the Cata10gue of 3e1ected Compact аа1аХ1еэ and Post-Erupt1ve Ga1axies (Zwicky) is obtainable from Miss Margrit Zwicky, Bahnhofmatte 1, СН - 3113 Rubigen (ВЕ) 3witz er1a.l1d . The current1y-known examp1es of 3eyfert ga1axies are to Ье found . . Weedman, D.W. 1976, Q.J. Ноу. Astr. 30С., 17,227. 1.11: 1977, Аnn. Неу. Astr. & Astrophys., 15, 69. 1978, Моn. Not. Ноу. Astr. 30С., 184, 11р. Fina11y, for аn up-to-date 1ist of Q30's there is: Hewitt, А. 1980, Ар. J. 3ирр. 43, No. 1. Burbidge, а.

9. OBSERVATION OF GALAXIES INTRODUCTION. External galaxies present the visual observer with various tures which, in тапу cases, he hopes to Ье аЫе to observe. The [еа ess with which such observations are carried out depends ироn 5UC~rous factors; these are а) Galaxy type; Ь) Distance; с) Galaxy ~~lination оп the plane of the sky; d) Effects of ga1actic ~sorption (if аnу); е) A1titude and [) Те1еэсоре in иэе, observing :ite and the observer's experience. In this chapter we shall Ье considering each of these aspects plus related factors. Selection effects are natural in astronomy, and in the field of galaxies these сап co1our the composition of cata10gues and hence the number of galaxies avai1able to the observer. Brightness is а natural criterion in the recognition and hence c1assification and cataloguing of ga1axies, but it is not the on1y оnе; allied to it must Ье an angular size that is enough to differentiate ga1axies from stars оп 1arge-scale p1ates. This combination of brightness and large angular size wi1l al10w тапу galaxies to Ье easily recogniseable, and hence а good proportion of the 4000 odd NGC galaxies are objects of this type. Objects of quite high brightness but smal1 angu1ar diameter were not extensively catalogued unti1 after the completion of the Palomar Sky Survey, which enabled large regions of the sky to Ье studied with relative еаэе. In this category fall тапу ga1axies in the Morphological Catalogue of Galaxies (мса), the Zwicky compact systems, Markarian galaxies, N-ga1axies and тапу other objects. For visua1 observers аn ana1ogous situation prevails; in the main it is on1y the brighter, 1arger galaxies which are selected for observation. Part1y this is probab1y due to the moderateaperture te1escopes used Ьу 1arge numbers of amateurs, as if more observers owned or had access to we1l-sited te1escopes of 16-inches aperture and over, тапу ga1axies of sma11er angu1ar size and low surface brightness wou1d Ье avai1ab1e. А further reason is that the standard source of ga1axies for тапу amateurs is the Atlas Coe1i and its associated cata1ogue. With а 1imiting magnitude of 13, Coe1i omits 1arge numbers of ga1axies which сап Ье of interest to visua1 observers.

М!gnitudеs. In 1eafing through а cata10gue of ga1axies, the first thing hat an observer wi11 general1y look f~~ are the quoted magnitudes. i~:se B~eт to often have а hypnotic effect, the attit~de.toward Ъ т be1ng virtua11y that of Ho1y Writ. Consequently 1t 1S easy to f~come ensconced in the strait-jacket of magnitude figures, and lnd that а11 other factors are, conscious1y or unconscious1y, relegated to oblivion. t

54

55

Observation of Galaxies

For the majority of catalogued galaxies the quoted magnitudes photographic. If the observer seeks out photovisual magnitudes aSar e being of more иэе, he will find that only а small percentage have Ьееn assigned these. Numbers of these magnitudes appear in the Atl as Coeli whi1e others are due to observations made with Holmberg with the 60 and 100-inch reflectors оп Mt. Wi1son in 1958.

Observation of Galaxies. Visibility, therefore, сап Ье defined as аn increasing function .ntensity gradient at sky level. А diagrammatic rendering of о! ~e factorB shows the situation best, using а late-type spiral eS th n example. Face-on, such а galaxy displays а low intensity В а :ient, resulting in low contrast with the sky brightness, while gra the edge-on position the steep intensity gradient produces а ~~gh contrast with the sky, аэ shown in Figure 19.

Magnitudes of ga1axies are difficu1t to derive, and сап invo1ve various corrections due to the effects of absorption within а given ga1axy, absorption in the Ga1axy itse1f and other factors. In particu1ar the faintness of the outer regions of ga1axies presents problems, and these are best solved Ьу taking а particular isophote and using оn1у the 1ight within this to derive а magnitude. The most accurate ру magnitudes are those of Ho1mberg for 300 ga1axies, the majority of these being spira1s. With irregu1ars and el1iptica1s thus pretty well exc1uded from Ho1mberg's sample, there is по universa1 spread of ру values which would Ье useful to amateurs. In the circumstances the best that сап Ье done is иэе the Ho1mberg figures where avai1able and pg values for the remainder. Magnitude figures alone do not always give а good indication of the visibi1ity of а galaxy; in particular late-type spirals and irregulars suffer in this way, аэ the distribution of materia1 in them is far from being similar to elliptical ga1axies with their smooth intensity gradients. In stressing the fact that magnitudeB of galaxies do not always tell all, we in по way intend to соnуеу the impression that they are of по иэе. Оп the contrary, they are of great value, but the other factors that contribute to а galaxy's visual appearance must а1во Ье taken into account. Аэ а postscript, it i8 best to эау that the only way to вее whether а galaxy is visible or not, or displays аnу detail, is to observe it, preferablY in the best transparency and seeing that сап Ье found. We shall по. discuss the other aspect8 of galaxies which bear directly ироn their appearance at the eyepiece. Surface Brightness. The surface brightness distribution acr06S the faces of gala xies will vary considerably аэ а function of galaxy type. We have already mentioned the 8trong increa8e in central brightness which i8 а feature of elliptical galaxies, barring dwarf types. This steep increase in luminosity results in high contrast with the sky, and contrast is а major factor in the observation of galaxies ог other objects with nеЬи1оиэ regions. It is contrast which makes n edge-on galaxies present more easily detectable images than face-o оnев, although there are exceptions to this, Buch ав the edge-on gc galaxy ТС 2233, with its overall low surface brightness.

Face оп: low contrast. ~

-~-level.

Figure 19. Respective intensity gradients of and а face-on late-type spiral.

аn

edge-on

The surface brightness distribution within аn object is defined аа the apparent magnitude per square arcsecond (mag эес-2 ), and уегу detailed surface brightness figures сап Ье obtained for galaxies. These сап show just how а given galaxy type will colour the results of visual observation, in particular with regard to late-type systems, Some irregulars, for example, шау only show а вшаll region of relatively high surface brightness, while in the ~азе of dwarf elliptical galaxies like the Draco, Fornax or ~Ulptor systems, there is по real concentration of stars to give ~nвe to re~ions ~f high surface brightness. The star distribution such obJects 1В rather analogous to а fairly rich star cluster, :nd аэ а result of this rnorphology such objects are detectable d~inly in the galactic neighbourhood, and еуеn at these nearby llstances are very low in surface brigh.tness. While ви! tably Soc at e d observers should Ье аЫе to register the Fornax and the a~Ulptor systems, others are totally beyond visual observation, сап Ье вееn Ьу taking the Local Group of galaxies.

Ь! ~he nearness of а galaxy does not шеаn that it is оЕ suitably g

Surface brightness to Ье вееn visually. Numerous dwarf irr-

56

57

Observation of Ga1axies

Observation of Ga1axies egu1ars and elliptica1s are nearer than М31 but попе are bright еn to Ъе эееn in te1escopes. Such objects а1эо furnish confirmation o~ugh the fact that magnitudes are not the оn1у criteria regarding ga1ax Y visibi1ity; тапу of them have apparent magnitudes of between 9 and 11 mag, the lowest being for the dwarf e1liptica1 Leo 11 (12.9 mag) Other, larger Loca1 агоир systems аге not оъэегуаыe visua11y, in . particular 1С 1613 and А1009. 1nspection of photographs of the forme shows а уегу faint object in which the region of highest surface r brightness in the ыеe is 23.76 mag эес-~; similar figures аге to Ье found for А1009. Тп contrast to the аЬоуе пеагЪу ga1axies, high 1uminosity objects of lower integrated magnitudes аге visiыe out to consideraыe distances, wel1 beyond the Loca1 агоир. For such objects it is on1y their type which al10ws them to register in moderate apertures. То conc1ude this section оп surface brightness we sha11 take two galaxies of identica1 type and эее how these re1ate to observation. NGC 1569 and А1009 аге both Mage11anic-type irregu1ars (ТВт), the former being at а distance of 3.3 Мрс and the 1atter Т.1 Мрс. The respective V magnitudes аге: NGC V • 11.16; А1ОО9 V • 11.6з. Despite the distance differences, NGC 1569 is much brighter and of smal1er angu1ar size; it is a1so the тоге lnc1ined of the two.

In Figures 20 and 21 оп the opposite page аге shown isophotes of thes e two ga1axies, depicting respective1y the central region of NGC 1569 and the tota1 агеа of А1009. For Figure 20 the питЬег 1 i dicates а surface brightness of V s 18.18 and the питЪег 4 of ,n. 18.48. The regions outside of this have surface brightnesses anging from V = 18.69 to V • 24.82. 1п Figure 21 1 indicates а rurface brightness of V • 23.4 and 2 of V • 24.42. Агеав exterior ~o the 1atter have surface brightnesses going down to В • 28.49. From this it сап Ье seen that the brightest region in А1ОО9 is not too different in surface brightness to the faintest region in the NGC 1569 isophotes. Add to this the тоге compact distribution о! materia1 in NGC 1569, and the combination accounts for the fact that whereas NGC 1569 is ап еаэу object in quite small te1escopes, АI009 is уегу much the oppo8ite, аэ the brightest region of surface brightness in this is due to а питЬег of blue supergiant stars. Аэ а further comparison _е сап take the пис1еиэ of the face~on Scd galaxy ТС 342, which is al1 that i8 visib1e of thi8 galaxy to the еуе, but which, for al1 its small angu1ar size, is easily recogniseaыe optically; this has а surface brightness of 18.56, а sizeable increase in brightness оуег both the brightest regions of NGC 1569 and А1009. Degrees of1nc1ination.

NGC 1569

А

в

1009

в

The extent to which а galaxy тау Ье inclined with respect to the contributes to their visual observability. Ed~e-on systems, epitomised Ьу NGC 4565 and MI04, сап disp1ay bright images due to their steep intensity gradients and high contrast with the sky. The тоге that а ga1axy approaches the face-on position, the less contrast wil1 there Ье, a1though а considerable part is played Ьу ga1axy type. оЬаегуег

With spira1s the sequence Sa- Sb- Sc wi11 show different degrees of central bu1ge and disk morpho1ogy. From Sa through to Sc the аrшз in the disk Ьесоте 1ess pronounced and the central bulge 1ess ~rominent. Late-type spira1s (Sc) will thus suffer most when their lnc~ination is face-on, а good example being М74, where the outer reglons of t~e d1sk is of уегу 10w surface brightness. А simi1ar Obje~t 1э M100, where in moderate apertures only the nuc1ear region ~~d lts immediate surroundings аге visible, the spira1 агтэ being уегу 10w luminosity, еуеп in photographs.

о

• Aperture

Aperture I

Figure 20. SB measures оГ NGC 1569.

О

I

I

I~O

I

~o

21. SB measures 1009.

Pi~ure

оГ А

(From АЫеэ, 1971. Qeproduced Ьу courtesy оГ U.S. Nava1 Obs.)·

g With За and Sb galaxies the structure of the spira1 агтэ i8 а pOOd dea1 тОге pronounced, and they аге тоге tight1y wound, thus oreSenting regions of higher surface brightness, even in the face.~ ~O~ition. Аэ di8tances increase the problems of visual si~hti~g8 30 Plra1s Ьесоте тоге acute, until eventual1y only high lUffilnoslty and E-types аге within the light grasp of amateur telescopes.

58

Observation of Ga1axies

Observation of Ga1axies. Some edge-on ga1axies disp1ay по indications of nuc1ear bu1ges , and perhaps the most we11-known ехатр1е is IC 2233. This object is not t Q faint to register in the 1arger amateur te1escopes, but other exampIO з such аэ MCG 4-29-60 are very faint. Such objects wou1d probably роsее extreme problems for the average amateur telescope, but determined observers тау feel inc1ined to attempt the feat, and therefore detail З of эоте of these objects wi11 appear in the 1ist of additional ОЬjесtз, In conc1usion it is instructive to note that the degree of intern 1 absorption shown Ьу ап edge-on ga1axy wi11 radica11y a1ter its а apparent radius. The absorption 1апе in MI04 is а good ехатр1е, this running right through the major axis, and if this ga1axy were to Ье эееп in а face-on position its radiuR wou1d probably Ье effectively increased. Spiral Structure. While the detection of very faint galaxies сап Ье а satisfying excercise in itself, the resolution of spiral arms and other features in galaxies is often еуеп more эо. Spiral structure is relatively еаву to discern in the larger amateur telescopes, but there are various indicators of spiral form which сап Ье эееп in smaller apertures. Ав dust lanes are аэ effective spiral arm tracers аэ young stars, ореп clusters and associations, spiral form шау Ье detected аэ regions of dark nebulQsity, which, a1though not a1ways эееп in their entirety, are often геаэопаЫу prominent at the eyepiece. The nearest galaxies in which spiral form is detectable аге M31 and In the former the spiral агтэ аге partia11y delineated Ьу two 1апеэ of dark nebulosity running a10ng the W edge of the ga1axy. These features are visible in apertures аэ эта11 аэ 8-inches, апа a1though эоте observers эеет ипаЫе to detect them, it is possible that they аге 100king for something 1еээ sizeable than these 1апеэ appear. Even if, for воше reason, the 1апеэ are not seen, their presence сап Ье inferred from the distribution of light in the ga1axy. Оп the Е ьогает of M31 the g10w of integrated star1ight fa11s away gradua11y to sky brightness 1eve1. In contrast, the W border of the ga1axy сап арреаг to Ье rather abrupt1y cut-off, due to the presence of the lane nearest to the centra1 regions. In М33 te1escopes of 8-inches aperture are аЫе to res01ve trac es of spira1 structure, and the эаше сап Ье said, a1though in 1esser degree, for шоге distant systems. Individua1 ехатр1еэ wi11 Ье found in the cata10gue and se1ection of drawings further оп in this vo1ume. М33.

Nuc1ei and Centra1 Regions. The nuc1ear and centra1 bu1ges of ga1axies сап form the basis of interesting visua1 observations, a1though these are, Ьу the very nature of the instrumentation uti1ised, very crude. In bright Local Group ga1axies nuc1ei and centra1 parts are easi1y эееп, but nothing

f interest morph010gica11y is apparent. If we wish to эее more of ~ terest, therefore, we must extend observations to more distant ~~jects. Here angu1ar sizes wi1l Ье much reduced, апа consequently must adopt the term 'nuc1ear regions' or, better perhaps, ~:ntral regions', in accordance with the data presented ear1ier. Мапу

features grouped c10se1y around nuclear regions are too often too faint to Ье resolved with amateur te1escopes. ;here are numerous ga1axies with such inner morpho1ogy, such аэ М95 and NGC 5383. In NGC 1087 and NGC 6607 the true nuc1ei 1ie at the епа of а bar of bright regions. Observations Ьу а we11-sited 16t- inch ref1ector in southern Ca1ifornia have fai1ed to show апу of these features, эо there is по 1ike1ihood of their being эееп with 1esser apertures. та11 апа

Visua11y, тапу ga1axies wil1 contain centra1 re~ions which blanketed Ьу high surface brightness nebu1osity, аэ is the саэе with NGC 4473, where amid the 1uminous materia1 а tiny central region is visible at high powers. Other objects present fair1y d1ffuse images, and the use of high magnification wil1 decrease the overall image brightness of such а ga1axy to ап unacceptable 1еуе1, if not comp1ete invisibi1ity. Such а step ир in magnificati< however, _111 not too detrimenta11y affect bright centra1 regions. For such observations the very best seeing is necessary in order that the эта11 region under scrutiny does not suffer distortion. There wi11, of course, Ье artifacts produced Ьу the 1ack of rea11y adequate res01ution, but at 1east in тапу instances эоте apparent structura1 aspects сап Ье perceived. аге

The re1ation of the central regions to the parent ga1axy сап also disp1ay interesting aspects. In эоте саэеэ the centra1 regions are offset from the apparent centre of the object, either a10ng the major axis ог a10ng the minor, whi1e dup1icity тау appear to Ье the саэе for эоте systems. Here, however, саге must Ье .taken with the observation, аэ often superimposed stars are invo1ved, and in the саэе of NGC 6207 the apparent nuc1eus is actual1y а superimposed galactic star.

In conc1usion we сап take Seyfert ga1axies, where the re1ative brightness of nuc1ear region8 to епуеl0ре varies considerabl~ The intensity of а few of these regions is extreme1y high, attaining i~ а few ехатр1еэ а surface brightness of 11 mag 8ес- 2 • It hard1y п:ес to Ъе said that such centra1 region8 аге of very эта11 angu1ar 81ZE and disp1ay по 8tructure at a11. It i8 of interest to note that the nUC1eu8 of the Seyfert NGC 4151, smal1 аэ it i8 оп 1arge ref1ector ~lates, is considerablyreduced when observations are made Ьу alloon_borne instruments, where atmosphere-dictated seeing is cOnsiderab1y dep1eted.

61

60

Observation of Galaxies

Observation of Galaxies ~mission

which is the brightest emission region in the galaxy, NGC 2404

Regions.

A1l emission regions in external galaxies are of sma11 angu1ar diameter when compared with the overa11 apparent size of the parent galaxy. Sma1l аэ these are visua1ly, it needs to Ье rea1ised that thes ате on1y the 1argest, and are, in intrinsic size, much greater than аn; in the Galaxy which 1ie re1ative1y near to the Sun. 1п addition, а further snag is that extraga1actic emission regions ате genera11y we11 immersed in quite bright areas made ир Ьу the 1ight of innumerable stars. This шау Ье compared with bright emission regions in the Galaxy itse1f, where, visually at least, contamination Ьу fie1d stars is not at all great. The number of known emission regions varies from galaxy to galaxYi most are beyond visual scrutiny, but а number are bright enough and large enough to Ье эееп in suitable amateur telescopes, and for шапу high quality seeing is required in order to differentiate them from stars. The nearest large, bright emission region in ап external galaxy is the 30 Doradus nebula in the Large Magellanic Cloud, which has а шазв of about 106 М , and is а bright telescopic object. Apart from this object, the шов~ obvious emission region is NGC 604 in М33, with а шавв of about 2 х 106 М • While а good dea1 farther off than 30 Doradus, NGC 604 is nevertheless not а difficu1t object to оЬветуе.

е

Ав in the galactic emission regions, the extraga1actic опев emit а degree of their radiation in the forbidden lines of twice-ionized oxygen([OI11])at wave1engths of 4959 and 5007 1. This is near to the еуе'в peak response at 5500 Х, and this, plus the strength of the [О111] emission, accounts for the greeny tinge to ga1actic nebulae of sufficient brightness. The extraga1actic emission regions, however, are too faint for the colour to register in amateur te1escopes, еуеп when their abundances are simi1ar to those in galactic nebulae. М42, for ехашр1е, has ап oxygen abundance similar to that of NGC 604. 1п the fina1 analysis, the observer wi11 have to make ир his own mind аэ to the actual nature of suspected emission regions, ип1еэв photographs are оп hand which сап Ье referred to. 1п зоте ga1axies nebulae are we11 within the 1ight grasp of the 1arger amateur te1eзсорез, and шау Ье вееп ав being located within spira1 arm regions от, in the саэе of irregu1ar ga1axies, at апу point within the оует­ al1 image. 1п the Loca1 Group irregu1ar ga1axy NGC 6822 are four emission regions of quite large size. For observers at mid-northern 1atitudes these wi11 Ье very difficu1t, if not impossible, to зее, but for those who тау fee1 inc1ined to try, details of these objects will Ье found in Appendix 2. Ав ап example of the emission regions within а ga1axy, and how а 1arge amateur telescope is incapable of registering them, we сап ta ke the Sc galaxy NGC 2403. А drawing of this object, made with а 16_in Cn 1l . re f1 ector, wi11 Ье found оп page 16В, and notable in t h е d raw1ng ~. S a 1 emission region situated towards the end of а gradually fading ЗР1та

;rm~ther such regions are visible with the 16-inch, but there are а

°od шапу, and numbers are visible with а much 1arger aperture, ав in th~ catalogu:. However,.concentrating и~on th: .ngle emiSS10n reg10n вееп w1th the 16-1nch, and compar1ng th1S s:th the 1arger, brighter regions аэ shown оп photographs, we find W1great difference. Figure 2~ shows over 80 of these regions, and :ету apparent in their distribution is the de1ineation of spiral structure.

:~11 Ье show~

I

•• .. , • • ... . •• • .• • . .. ~ •• .' • • •• •• • • •• -. • • •• • ,. • #, . . r • .

..

.}

"

х

.,~

••

•

• ., •

~.

• #

••

•

~

~

•

,

• Figure 22. Bright emission regions in NGC 2403. The cross marks the position of the nucleus.

6~

62

Observation of Ga1axies.

Observation of Galaxies Peculiar, Interacting and Compact Galaxies. Мапу Pecu1iar and interacting systems are easi1y visible with sma1l te1escopes, but with regard to the observation of апу of the material giving rise to these c1assifications it сап Ье categorically stated th t in the overwhelming number of саэеэ nothing wi11 Ье эееп. The reason fa this i8 that the relevant structures are mainly of very low surface Or brightness, this being the саэе whether they are in inner or outer regions.

These types of galaxies, however, still afford much of interest to the visual observer, who сап se1ect objects within а given group for observation. А good group of objects for such а programme ате those double systems of the M51 type, of which тапу examples exist, a1though тапу are faint, particularly the smaller associated systems. А further group of objects are those whose makeup differs from ellipticals от spira1s but are akin to irregu1ars in that they contain ionized gas. These galaxies are notable for the fact that most of their radiation сотеэ from young stars and associated emission regions, and with so much of the latter being present, which radiates effectively at visible wavelengths, particularly the [OI1:(] lines of forbidden oxygen, they сап Ье of quite high apparent brightness. Мапу are compact objects, which wi11 Ье covered shortly, but others are of quite 1arge angular size in comparison with the compacts. А good introduction to such systems is the double galaxy NGC 3690/1C 694, which, a1though having а fairly low magnitude, сап Ье seen with еаве in moderate apertures. Ring galaxies, ав а class of interacting objects, are all rather faint and of small angular size. The first visual detection of ring structure in а galaxy was made in 1886 with the 26-inch refractor of the Leander McCormick observatory in the U.S.A. The ga1axy was NGC 985, which, however, is not а true ring galaxy, as the annular structure i8 formed Ьу а curling spiral arm. True ring systems wil1 not show their structure in the usual run of amateur telescopes, but, as with other objects, а rea1 interest саП Ье achieved in just finding them. The writer has made numerous attempts to observe the ring galaxies Arp 148, 11 Hz 4 and VI1 Zw 466; in all caS es the observations were foiled Ьу poor seeing. As well as transparency o~ а high order, good seeing is essential in the observation of objects о sma11 apparent size,' as they cou1d in тапу instances Ье mistaken [от stars. 30 much overlaps in the context of classification that it wi1l софе as по surprise to 1earn that ring galaxies сап also Ье classed aS compact systems, and the aboye~mentioned У11 Zw 466 is such а cas e • Furthermore, there are sti1l compact parts of galaxies which соте in to the present category, such as the ring around the nucleus of NGC 1543' which is catalogued аэ V11 Zw 8. At 14 mag, this is nonetheless not exceptionally difficult for telescopes of about 8-inches upwards. i tP V1I Zw 8 is, however, stil1 quite sizeable in extent when compared W

е

of the compact ga1axies proper.

А

glance through the 1ists of

Э~:эе objects demonstrates this wel1 1 and we find that a1though воте ~f the outer regions т~y extend to 30.arcseconds in angu1ar dia~eter

ch areas are very falnt, апа the brlghtest parts of the ga1axles а sU ch sma11er, between 2 and 1a arcseconds. Observations of such m~jects, therefore, wil1 require high-qua1ity seeing in order that ~ьey are аЫе to Ье differentiated from stars. A1though such observatio ns сап do по more than identify these sma1l ga1axies, eventua1 suc cess is rea11y а reward in itse1f, considering the difficu1ties which abound. 1n conc1uding this section we show in Figure 23 а smal se1ection of the structures exhibited Ьу compact ga1axies; angu1ar sizes are a1so shown, giving ап indication of the structure which, a1though beyond the 1ight grasp of moderate te1escopes, is compresse in эисЬ sma11 angu1ar sizes.

~

,;} '.~.y""';

1 Zw 1

41'......."

~

V Zw 242

• II Zw 1

" \,


t

0459+03

"

/'

1II ZW 33

",.,'1

"

,/

V Zw 297

Figure 23. Six compact ga1axies from Zwicky's cata1ogues. The sca1e app1ies to a11 the six.

65

64

Observation of Ga1axies.

Observation of Galaxies. Supernova monitoring. 1п the field of extragalactic astronomy there is little that the amateur сап do, and апу useful work shou1d therefore Ье we1comed unreserved1y. Monitoring se1ected ga1axies for supernovae is а саЭе in point, and the оп1у requirement is а suitable te1escope, (upwards of 6-inches aperture), а fie1d drawing of each ga1axy and fina11y perseverance and good 1uck.

The first visua11y detected supernova in ап externa1 ga1axy was S Andromedae, which occured near the centre of М31 in 1885. Since this first sighting the number of known supernovae has increased considerably, and since the 1885 sighting 478 have Ьееп recorded ир 1979 Dec. The majority of these occur in the 14 to 20 magnitude range, with а peaking in the 16 to 17 magnitude bracket (85). 1f we take а теап 1imiting magnitude of 14 for the majority of amateur te1escopes, we find that 61 supernovae have Ьееп discovered ир to this 1imit, and that 30 of them are in the 13 to 14 magnitude range. The visual observer, therefore, has only а chance of catching а small percentage of future supernovae, and should prepare а thorough set of drawings of each selected ga1axy showing all nearby field stars to the galaxy, being careful to remember that the outer regions of ga1axies, where тапу supernovae occur, are far too faint to register in te1escopes, and that therefore а supernova тау wel1 appear well beyond the apparent optica1 boundaries. 1t is late-type galaxies which mainly produce supernovae, and эоте of these have produced more than опе outburst, NGC 6946, for ехатр1е, having spawned five. Judging from past discoveries, it is not the assiduous supernova hunter who discovers опе of these events, but а random sweeper of the sky or а comet-hunter. А1эо тапу эеет to regard the activity аэ irksome, but опсе the initial groundwork has Ьееп covered, then the actual checking of each object is а relative1y rapid affair, and the observations сап Ье quite easily fitted in with other programmes. Variable Extragalactic Sources. Мапу galaxies are variable, the nuclei of эоте Seyfert ga1axies, for example, p1us QSO's and BL Lac objects. 1п the саэе of the former, the f1ux variations are of smal1 amplitude, and accurate photometry is requires in order to realise the light curves. The BL Lac objects, аэ well аэ the QSO's, unfortunate1y reach low magnitudes, еуеп when at maximum, эо will only Ье within the light grasp of the 1arger amateur te1escopes, and еуеп then on1y at odd periods. Ап a1ternativ e method of obtaining 1ight curves is to photograph the object and then compare апу brightness changes with wel1-ca1ibrated fie1d stars. Pho to ' graphy, however, is not within the bounds of the present уо1ите, but ~ 1ist of а few variable sources is given in Part Three. Finding char ts

paris on star sequences are a1so given, аэ for the visual еуеп the random checking of such objects is of interest fo] bserver . о with suitably 1arge lnstruments. thO Se 1 conclusion, galaxies сап Ье observed for а variety of reasons. n h for а faint object, 1arge or smal1, сап Ье reason enough, The searc f 1 rticularly when ear1ier attempts have Ьееп unsuccess u • ра t've1y various objects сап Ье checked for апу structura1 na Alte: ~Pira1 or otherwise, or random observations сап Ье made witb detal l , 'cular scheme in mind. Whatever the approac, h th е ' see k'lng ои,• t по par 1 1 t 1 t . о! these often faint, often historic and often ~nusua ех raga ас l( wi11 continue to attract future generatlons of observers. systems

an d сот

67 РАНТ

TWO

А

CATALOGUE OF GALAXIES.

INTRODUCTION. ~he cata10gue contains observations of 275 ga1axies made Ьу 19 vers using te1escopes of 152 to 2i-inches aperture. Fo11owing ob~erwi11 Ье found 156 fie1d drawings of ga1axies, most of which are ~b~~ьe cata1ogue, a1though а few have Ьееп inc1uded which are not. ~~ certain cases more than опе drawing has Ьееп assigned to ап object ~o shOW the effect of different apertures ироп it. The extreme 1eft sides of the 1eft-hand pages show the Webb S ciety cata10gue number (WS); these continue in sequence from the l~st cata10gue entry in Vo1ume 3 of this series. Each WS number is fo11owed Ьу the actua1 designation of the ga1axy. In тапу cases there is more than опе designation, and these appear be10w the NGC or IC number, and comprise the Messier number, (М), the number in the catalogue of Interacting Ga1axies of Vorontsov-Ve1yaminov, (VV), the number in Arp's At1as of Pecu1iar Galaxies (Arp) and the number from the 1ists of ga1axies showing u1traviolet excess of Markarian (~~n). In воте instances а ga1axy wi11 Ье found to have two NGC numbers or an NGC and ап IC number, this being due to errors in these cata1ogues. The remaining data, covering the greater parts of the pages, is as fo11ows. Upper Line. (а) Positions for 1950.0.

(Ь) Magnitudes of the ga1axies. Those magnitudes with two p1aces

after the decima1 point are the very accurate Holmberg (1958).

ру

magnitudes of

(е) Angular diameters in arcminutes. Ho1mberg diameters are shown to two decimal р1асеэ.

(d) The abbreviated form оГ the re1evant conste11ations.

~eond and Subseguent Lines. F1rst the ga1axy Hubble type 1э given fo11owed 1п воте cases Ьу the revised type of de Vaucou1eurs. Fo11owing this wi11 Ье found radio ~ource identifications, where these occur. PKS sources are from the A~rkes survey, and 3С and 4С sources from the Cambridge surveys. ter this апу X-ray and IH source wi11 Ье shown. Comp1eting these S~etions wil1 Ье апу structura1 aspects of the ga1axies of interest, ~fl SUpernovae (SN) known ир to 1979 Dec, and finally апу membership а group or c1Gud. (DDO = David Dun1ap Observatory).

~al

Observations. The Obs d~ta below the dotted 1ines disp1ay t~e visua1 observati~ns. in ervat~ons are set out in order of decreas~ng aperture, the f~gures parenthesis, (16) (8t) etc., being the respective apertures in

69 68 А

inches.

А11

А Cata1o~ue

Cata10gue of Ga1axies.

quoted magnitudes and angu1ar sizes are

еуе

estimates

оп1у.

Fie1d Drawings. These number four to а page, and are shown in circ1es of 56 тт diameter, regard1ess of the actua1 fie1d diameters in arcminutes. For most the who1e fie1d is shown, but in а few саэеэ оп1у the object and its immediate surroundings, this being done main1y for observations with 1arge apertures, in order thatthe detai1 recorded is presented at а suitable sca1e. Iп а few instances по sca1e was avai1able, but for most objects the tota1 fie1d is shown in arcminutes. List of Observers. The fo11owing 1ist gives the names of the observers whose work appears in the cata1ogue, p1us detai1s of the te1escopes used and their locations. D.A. Allen

152-inch

R.J. Buta

60 12 107

J .К. Irving J. Тоопе

Ang1o-Austra1ian Observatory. Siding Spring, Austra1ia. Mount Wi1son, U.S.A. Cambridge, U.K. McDona1d Observatory. University of Texas, U.S.A.

82

"

It

Jt

з6

tI

tI

30 12t

tI

tI

"

tI

tI

18 18

2!

lVl.J. Thomson G.S. Whiston J. Perkins G. Hurst R.J. Mora1es

1бt 16 14 10 10

S. Selleck

10

" tI

Sa1ford, U.K. 11

"

fI

"

Santa Barbara, U.S.A. Wit1ey, U.K. Kirkby-in-Ashfie1d, U.K. Ear1s Barton, U.K. Тисэоп, U.S.A.

8

Santa Barbara, U.S.A.

6

Е.З.

Barker D. Chi1ds Т. Davies S.J. Нупеэ А.Р. Wi1son Р. Brennan

8t 8t at 8t 8t 8

Herne Вау, U.K. Luton, U.K. LLandudno, U.K. Crewe, U.K. Scunthorpe, U.K. Regina, Canada

6 K.G. Jones К. Sturdy

8

6

Winkfie1d, U.K. He1ms1ey, U.K.

of Ga1axies.

Observers and Accredited Ga1axies. . . ~ fo11owing 1ist shows а11 the ga1axies that appear ln the flrs T~e of the cata10gue p1us the initia1s of the respective observe sectlon NGC 9з6 GW, DAA, JT. 16 lVlJT, DC. NGC 949 GW, RJM. 23 RJB, JKI. 972 RJB, MJT, ESB. 55 RJM. MJT, КН. 1023 147 MJT, РВ. GH, ЗЗ. 1052 160 GW. DAA, SS, RJM. 1055 169 MJT. RJB, G1N, KGJ. 1068 181 GW. 1073 SS. 185 MJT, ЗЗ. 1087 GH. 205 SS. 1090 GH. 221 РВ. 1084 MJT, ЗЗ. 224 SS. KS. 1156 RJB. 247 SS. 1169 MJT. 253 MJT, RJM. 1300 RJB, MJT. GH, SJH, РВ. 278 1309 MJT. 300 RJM. 1332 SS. 404 GSW. 1337 MJT. 407 GSW. 1343 ЕЗВ. 410 GSW. 1421 MJT. 414 GSW. 342 ESB. IC 467 GSW. SS. 1465 GSW, SS. 488 ЕЗВ. 356 IC 520 MJT. 1560 MJT. 524 MJT, зз. 1569 RJB, ESB. 523 DAA, ESB. 1637 RJB, MJT. 584 SS, РВ, JT. 1784 MJT, SS. 596 SS. MJT 1888 598 RJB, GW, DC, KS. MJT 1889 615 ЗЗ. MJT. 2146 628 RJB, MJT, KGJ, ЗЗ. SS. 2207 636 SS. 2276 MJT. Ie 1727 RJM. 2403 RJB, RJB, MJT, KGJ, КН. 672 MJT, RJM, SS. 2537 RJB, MJT. 691 GSW. IC 2233 MJT. 697 GSW, DAA, SS. 2523 MJT. 720 JT. 2549 ESB. 736 MJT, RJM. 2608 GSW. 750 GSW, RJM, DC. 2613 MJT. 751 GSW. 2639 JP, ЕЗВ. 761 GSW. 2655 PJМ, KS. 172 MJT, DC. 2672 MJT. 179 РВ. 2681 MJT, SS. 784 RJM. 2683 KJI, MJT, DC. 890 GSW. 2685 MJT, ЕЗВ. 891 RJB, GSW. 2692 ЕЗВ. 925 RJB, MJT, RJM,

71 70 А А

NGC 2713 2719 2775 2782 2787 2841 2859 2872 2874 2903 2911 2964 2968 2976 3031 3034 3067 3079 3077 3115 U 0549 3166 3169 3185 3184 3187 3190 3193 3226 3227 3245 3310 3351 3353 Зз68

3377 3379 3384 3389 3412 3414 3430 3432 3445 3458 3504 3521 3556 3593

DAA. DAA, MJT. SS.

NGC

Е8В,

з627

3628 з631 з646 з665

РВ.

JT, KS. MJT, ESB. GSW, RJM. GSW. GSW. RJB, MJT, TD, G8W MJT. MJT. MJT, 88, К8. RJB, MJT, 88. RJB, MJT, КR. 88. JP, 88. MJT, Е8В. RJB, MJT. DC. G8\N, 88, К8.

Cata10gue of Ga1axies.

Cata10gue of Ga1axies.

3765 з690 тс К8.

К8.

GH, 8JH, MJT, S8. MJT, 8JH. MJT, GH. MJT, КR. MJT, TD. MJT, TD. ESB. RJB, MJT, RJM, К8. RJB, 88. GH. DC. JP. DAA, 88. 88. 88. G8W. DAA, TD. TD. G8\V, Е8В, К8, DB. GH. GH. 88. JKI, Е8В. RJB, MJT, ESB. G8W. 8S.

694 3718 3726 3729 3938 3810 3877 3893 3898 3921 3949 3953 396з

3982 3992 4026 4027 4038 4039 4041 4051 4088 4100 4111 4138 4144 4151 4157 4179 4203 4206 4214 4216 4217 4236 4244 4251 4258 4274 4278 4290 4314

GSW, TD. GSW, KGJ. JP, KS. RJB, MJT. KGJ. GSW, ESB. DAA, ESB. DAA, ESB. DAA, MJT, MJT. RJB, MJT, JP. 88. APW, KGJ, RJB, MJT, MJT, KGJ. JP. MJT, APW. RJB, MJT, MJT, Е8В. KGJ. MJT, GH. MJT, KGJ. RJB, MJT. RJB, MJT, RJB, MJT, MJT. MJT, Е8В. RJB, MJT, RJM. JKI. JP. GH. RJB, JKI, 88. MJT, К8. KGJ. MJT, RJM. RJB, Е8В. MJT, К8. MJT, Е8В. RJM, Е8В. MJT, KGJ. DAA, К8. RJB, MJT, RJM, К8. GSW. RJM. GSW, KS.

NGC 5600 DC. 5665 DC. 4346 5676 GSW. 4з95 5678 RJB, MJT. 4414 5746 RJB, JKI, KS. 4419 РВ. 5820 MJT. 4448 ESB. 5846 GSW, DAA, KGJ. JT. СС. 273 5850 RJB, DAA. JC JKI, RJB, ESB, KGJ 4449 RJB, 5866 RJB, MJT, Е8В. KGJ. 4485 RJB, G8W, 5879 G8W, К8. KGJ. 4490 RJB, G8W, 5907 GSW. 4494 DAA, JT. 5929 G8W. 4527 DAA. 5930 G8vV. Е8В, К8. 4565 RJB, MJT, 6052 DAA, RJM. К8. 4605 MJT, Е8В, 6181 RJB, MJT. 4618 RJB, Е8В. 6217 MJT. 4625 RJM, DC. 6207 JKI, DAA, KGJ. 4627 RJB, MJT. 6384 MJT. 4631 RJB, MJT, Е8В. 6503 G8W, Е8В. 4651 88. 6643 MJT, ESB. 4656 RJB" G8W, KGJ. 6764 RJB. 4657 RJB, G8W, KGJ. 6822 Е8В. 4665 DAA. 6946 RJB, MJT, KGJ. 4666 GSW. Lac кл. BL 4670 MJT, ESB. MJT, GSW. 7217 4676 RJB, MJT. КR. 7331 RJB, MJT, DC, 4710 RJB, GSW. DC. 7335 RJB, MJT, 4725 RJB, PJM, KS. 7448 Е8В. 4762 MJT, Е8В. 7463 G8'N. 4775 MJT. 7464 G8W. 4793 lvIJT, Е8В. 7465 G8N. 4826 DAA. 'RJB, G8W, KGJ. 7469 G8W, 8JH. 4861 RJB. IC 5285 Е8В. 4868 G8W. EJC, Е8В. 7479 RJB, MJT, 49Jb RJB, К8. 7603 DAA. 5005 MJT, G8W, KGJ. 7640 RJB, G8W, Е8В. 5033 RJB, RJM, KGJ. 7678 RJB, Е8В. 5055 MJT, KGJ. 7973 Е8В. 5128 MJT, DD. 5194 RJB, G8W, GH, KGJ. 5195 RJB, GSW, GH, KGJ. 5198 MJT, G8iV. 5221 G8W. 5222 G8W. 5236 RJM. 5248 RJB, MJT, К8. 5273 JP. 5297 MJT, JP. 5371 RJB, MJT, G8N. 5457 RJB, GSW, KGJ, KS. 5583 GSW, RJM.

NGC 4з19

К8.

К8.

К8.

83.

KGJ.

RJM. RJM.

SS.

Е8В.

Е8В,

88.

GSW. RJM. MJT. JT.

73

72 А

Catalogue of Galaxies.

\lS

few words are necessary regarding the composition of the following catalogue. Ву по теаnэ every galaxy observed Ьу Webb 80ciety members is included in it, and the reason for this is аэ follows. If every object were listed it wou1d run the risk of being а rather monotonous ama1gam of faint, feature1ess objects interspersed with those which disp1ay эоте kind of structure to amateur te1escopes.Whi1e the search for very faint objects сап Ье most interesting and cha11enging, to read of the resu1ts, comprised of а few words, is not inspiring. Consequent1y in the present cata10gue we have main1y se1ected those objects which disp1ay varying degrees of morpho1ogy to different apertures and cut down heavi1y оп those which ао not. The 1atter inc1ude e11iptica1s and 80 types, Ьу their natures feature1ess, р1иэ тапу spira1s and irregu1ars. For those who wish to extend their te1escopes to near the 1imit, тапу faint objects wi11 Ье found in the 1ist of additiona1 objects, together with brighter ехатр1еэ, and we trust that а sufficient variety is set out to cater for а11 types of te1escopes and observers. А

4;0

NGC

Dec

RA

Ca-t 1б

00 об.5

+27 27

nатеэ

were omitted from the 1ist

,

1 3.2

NGC 22, 14~9, 1 .8

Е3.

(1б)

х

AD

Соn

х

Peg

1.0

,

Round, with

а

0.7

, - - - - - -

1.4, 1ies 11 .5 N.f.

- - - - - - -

- - - -

slightly brighter centre; the

outer nebulosity is of uniform surface brightness. (8!) A1most ste11ar at LP;

а

1itt1e outer materia1

visible at I'IP.

-431

NGC

23

00 07.3

2.2 х 1.б

+25 39

Peg

Sb. (3б)

Bright, extended e11ipse;

а

bright nuc1ear

structure is noticeably e1ongated; two weak spira1 enhancements emerge from opposite sides of the nис1еиэ, оnе

The fo11owing observers' page б8.

т

оп

оп

the S end.

curving towards А с1оэе

а

bright star attached

double star

(18) Slightly pointed at the SE еnа; ste11ar

Denis Dutton, 12!-inch, Ca1ifornia.

nис1еиэ

Chris C1ayton, Bath, U.K., 10-inch.

with

suspected

оп

а

star quite

с1оэе

to SE

anа

а

star

the NW side.

Dave Branchett, Bishopstoke, U.K., 5-inch. 432 The fo11owing cata10gue entries shou1d РВ.

NGC 5474

MJT,

NGC 5533

G8#, 8S.

арреаг оп

page 144.

NGC

55

00 12.7

-39 28

7.8

25.0

х

3.0

Sc-1

SB. PKS 0012-394. The spira1 structure is weaker in the W part. Member of Scu1ptor Group. Other members not in this volume are NGC's 45, 7793 and possibly IC 5332. (3б) Near1y edge-on and appears asymmetrica1 with эоте

signs of dust near the bu1ge, which is diffuse,

broad and somewhat e10ngated with the S edge sharp; SE of the bulge it is strongly curved

anа

lined with

4 or 5 faint knots; N edge of the curve is sharp. (8) Large and уегу long; bright nucleus shows two almost stellar condensations and is off-centre; mottling evident in the central area.

75

74

WS

433

Cat NGC

147

DDO

3

00 30.4

1бо

15. О

х

9.0

шiddlе

to

а

of the Local Group.

- - -- - - -- - - -

brightest part about 30"

suspected

+23 41 а

Contains

diaтeter.

3.5

13.3

very

sшаll,

х

1.1 а

isolated nucleus in

439

(1б) 8mall,

faint, diffuse ellipsoid.

+23 43

х

Arp

282

Mkn

341

8Ь + соmр in contact to Б. NGC 1б2, 2:8 S.8.f. probab1y а star. 1С 1559, 13 ~, lies 1:0 S.

13.3

3.5

1.1

NGC М

- --

00 34.2

Arp

the second nucleus beiryg nuclei surrounded

00 35.4

Ьу а

+08 22

оп

the 8 end;

2.8

х

2.3

32 1б8

х351

8.р.

the centre.

+40 3б

00 39.9 Е3. А faint,

8.1б

12.0

х

8.0

And

diffuse plurne of material associated.

Member of the Local Group.

-----------

- - - - - - -- -

(8) Slightly extended in РА 1500 - 3300; stellar nucleus within gradually fading nebulosity.

is

440

both

NGC

224 31

00 40.0

+41 00

200

3.47

х

80

Sb. Radio source. Nucleus about the size of

And а

large

globular cluster but nearly 100 times greater in and 20 tirnes greater in

mаББ

luшiпоsitу. б88 Н

II

regions. Over 120 known novae. SN: 1885 - 5~8.

nebulous envelope.

14.3

221

And

(1б~) Easily visib1e х84; х17б appears bi-nuclear,

1'1ernber of the Local Group.

-----------------

Pse

SBc:8B(rs)bc.

185

= -5.2. Member

centre, which appears offset; at HP а star

00 33.4

And

(8) Elongated N-S; brightens gradually to the

stellar nucleus.

169

NGC

2б.0 х 1б.0

8.17

аЬ

М

[37

+4125

quite faint, irregularly round; it

NGC

181

00 37.б

Е5. The brightest stars have М

- -- - - - - - --- -- -

faint, doub1e outer ring.

NGC

205

AD

m

(б) Faint stellar nucleus in faint nebulosity;

8а.

435

NGC

A!ld

Dec.

НА

Cat

СОп

:tV:ernber of Local Group.

ЙЕ5.

brightens in the

NGC

AD

12.0

+48 14

(1б~) Large,

434

rn

Dec

НА

Соп

- -'

(8) Very bright, large spherical core with а stellar а

(1б) Faint, srnall, slightly elongated in РА 1350,

nucleus; surrounding this

00 3б. 2

W part of major axis, the опе closer to the nucleus

Е2.

А

+48 03

11 • О

, 14

х 12

-

cas

globular cluster lies 1.1 S.f. the nucle uS ,

Mernber of the Local Group.

-

-

large halo with exten-

sions running NNW-SSE; two dark lanes run along the I

the rnore obvious and about 15

long; the star cloud

NGC 20б shows as а nebulous knot in the 88W end; а '

second,

fainter knot in the saтe extension, about

(1б~) Fairly bright, large, irregular; brightenS

midway between the nucleus and NGC 20б.

towards the centre.

(б) Nebulosity cuts off sharply to the W and fades

(8) Possib1y slightly extended E-W with а hint о! mottling; slightly irregular at

ИР.

rnore gradually to the Е; nuclear region stellar at х24,

and of distinct size at

х120.

77.

76 \olS

441

Cat NGC

Dec

НА

247

00 44.6

-2120

m

10.7

AD

Соп

18.0 х 5.0

Cet

"S

445

SAB. Member of Sculptor Group. DDO 6, 14~9, lies

Cat NGC 404

ESE.

А

NGC

253

00 45.2

-25 33

22.0 х 6.0

7.0

Scl

14~0. Member of the

SC. PKS 0045-25. SN: 1940 Sculptor Group.

х59.

the N

--

-

NGC 407

а

extends along major axis; evident, especially

оп

р

NGC

278

00 49.2

+47 17

2.8

10.5

Sc:SAB. Contains several knotty,

0.35

h

m

09.5, +32

о

- - -

Psc lying

I

58

а

is probably

star.

N-Sj brighter towards the middle.

aпd

447

NGC 410

01 08.2 Е

+32 53

2.3

12.6

х

Psc

1.8

• In group of elliptieals.

extension. (16) Hound and brightj mueh brighter to the middlE

iшрrеssivе.

448 443

х

2.0

14.3

(16) Quite bright and small; elongated approximatE

(8) Bright; very sшаll core inside mid region with mottling evident in the latter;

And, close to

the field. +35 21

------

number of dark lanes

the N edge of

01 07.8

at OI

the major axis

extending N.f., S.p.; central area non-stellar

swaтps

~

SO/a. In group of ellipticals. NGC 408,

- - - - - - - - - - - - - - - - -.

(16~) Very bright, large and long,

And

(16) Very bright and round; diffuse outer halo and much brighter to the middle;

centre; difficult at powers over

Соп

6.0 х 6.0

11.3

I

(10) Large, fairly bright with а slightly brighter

442

+35 27

AD

E/SO. Possible member of the Local Group.

chain of faint, mostly spiral, galaxies

lie close to the NE.

01 06.7

m

- - - --- - - -- - - - - -- -- - - - -

I

40

Dec

НА

х

2.8

NGC 414

01 08.5 ?

Cas

0.8

+32 50

х

0.4

Pse

In group of elliptieals. Double system.

шаssivе аrшs.

(16) Small, round, brighter to the middle. (10) Very bright and sшаll, appearing as а round glow without anу defined nucleus; 8~0 star N.f. (8~) х111 а pretty faint stellar nucleus in faint

(6) х50 sшаll, faint and round; suspected stellar х155;

lies in

а

fine LP field.

-------------------------------444

NGC

300

00 52.5

-37 54

NGC 467

01 16.6 80. Contains

+03 02 а

13.3

2.4 х 2.4

weak, narrow dark lane.

Cet ~ember

of

NGC 467, 470, 474 group.

diffuse nebulosity.

nucleus at

449

9.68

20.0

х

IO.O

Scl

8А.

(8) Bright, starlike nucleus with а very large faint nebulous shell, the latter not too prominent and somewhat difficult.

(16) Quite bright; slowly brightens to the middle and

а

faint, stellar nueleusj slightly elongated

approximately N-8j in and NGC 474 (Arp 227).

saтe

LP field as NGC 470

78

79

ws 450

Cat

NGC 488

НА

01 19.2

Dee +05 00

AD

т

6.0 х 4.3

11.6

Рзе

Sa. Contains а weak, smooth outer ring. NGC 49 т ' 15.5, lies 8 N.f.

°t

NGC

523

01 22.5

Arp

158

Рее.

1У ZW 45

nebulosity easily visible at

х160

Ьу

and

(8~)

х222.

6.8 х 2.9

d~.,arf

-

3.2

13.5

eoтprises

х

Соп

0.8

Pse

three objeets, ineluding

system.

involved, the W

diffuse

(10) Faint, diffuse pateh; по detail seen. 451

а

+33 46

Possibly

AD

т

(60) Very elongated nebulosity; two bright region

(16) Considerably bright, large and eireular; а bright, eentral eore is surrounded

Dee

НА

Cat

COn

454

brighter

~nd eoтpaet.

Faint, extended nebulous blur at LP anа ИР.

NGC 584

01 28.8

1С

Е4.

1712

опе

-07 07

РК8

0128-07.

11.6

Meтber

2.0 х 1.2

Pse

of Cetus 11 Cloud.

NGC 520

01 22.1

уу

1rr 11. Strongly peeuliar. Two apparent objeets

(10) Round with ill-defined edges; brighter eentrl

plus two streamers.

with stellar nueleus;

231

Arp 157

+03 33

11.54

Рзе

------

тore

Е

brightest part of the galaxy is

оп

оп

N edg,

(2i) Diffieult; gradual eentral brightening.

being the

eonspieuous, long and nearly straight; the

possible star

(6) Round anа faint; proтinent stellar nueleus.

(30) 1rregular shape split into two seetions Ьу а weak dust lane, the seetion to the

х178

455

NGC 59.6

the N tip of

01 30.6 Е2.

-07 17

12.2

0.6 х 0.5

Pse

Contains а distorted envelope with а faint tai

this seetion, and appears round and diffuse; the

leading to

seetion W of the dust 1anе is bent with а very

Member of Cetus 11 Cloud.

а

small spiral. 8imilar to NGC 7135.

faint knot at the kink; а seeond faint knot lies direetly opposite this

оп

the

Е

side; not

а

(10) 8mall, faint anа gradually brighter towards

very

bright objeet.

the eentre;

(16~) Quite large but not bright; elongated Ы.р.,

apparent

S.f.; х222 wider оп f end while the р end епаз

edge

in

а

point.

- - NGC - -524- - - - - - - - - - - - - - - - - - - 452 01 22.1

+09 17

11.5

3.5 х 3.5

РБС

80 or Е рее. 1п group of 80's, 8а'з anа others.

-- -- -- -- - --- --

456

а

х148 а

anа

very small, bright nucleus is

the edges

зеет тottled; оп

the N.p.

star suspeeted. 83.0 х 53.0

NGC 598

01 31.0

М

8e:8A(s)ed. РК8 0131+30. Contains over з60 known

33

+30 24

5.79

Tri

emission nebulae. 1ts globular elusters are bluer , than those in М31. Member of the Loeal Group.

(16~) Cireular with very bright eentre anа fain t surrounding nebulosity; dark mottling suspeeted iV

(82) NGC 604 - knot at еnа of ЫЕ spiral аrш. At х8

outer material, especially to N anа Е.

а faseinating objeet; 17 stars down to 18~0 or 18~

(8) Mottling possible х48; quite large anа bright .

plus definite signs of the assoeiated nebulosity, partieular

оп

the W side.

(36) 8piral strueture elear but eontrast poor; bot

80

81

VJS

Cat

НА

т

Dec

AD

(NGC 598 - М33 - continued). arтs

are lined

including

а

Ьу

knots and

а

(NGC 628 - М74 - continued)

enhanceтents

, SOffie

and contains

with two knots in its 8 half· th , е centra bulge appears very diffuse, broad and soтewhat

еУе.

А

chart

ог

ра t

тore

alтost

about 6

ches,

ироп а

and

х222

and

х333 а sтall, оп

fairly sharp nucleus which is

stellar and surrounded

,

diaтeter;

stand anything

тore

Ьу а

diffuse area

too faint and diffuse to than LP.

(6) Faint тass of light of еуеп intensity.

diffuse.

(8~) Defini te spiral forт in the shape of а reversei

'8' projected

а

(8) Hound, with

NGC 604 being the brightest; the other two are near the nucleus and are

тiddle

the N.f. outer edge.

the knots in М33, plus з6-iпсh observations , will Ье found in Appendix (16) Clearly spiral; contains three bright

appear only weakly

curving arc of brighter nebulosity suspected

1C 139, at the tip of the 8 ar~, shows as about а' across.

arтs

а

in

c'Onnected. (16~) Fairly bright, large and circular; brighter towards the

е

iттersed

nucleus, being

diffuse halo to which the

filaтent

extended N-8; NGC 604 appears like а nebul ous version of the Pleaides as seen with the nak d

по

arт

sтall

is the brighter; nuclear region is quite

and to th e conspicuous straight, narrow

dozen very faint stars about 1

AD

т

knot at the end and with patchy areas; the 8

few very faint stars; near

W of centre is

Dec

НА

cat

Соn

Соп

uniform haze; N

arт

459

NGC 636

of unifoI'l!

01 з6.6

-07 45

12.6

0.7

х

0.7

Psc

Е).

brightness, the S arт appearing to have two brighter regions; NGC 604 proтinent and about other nebulosity suspected only.

the centre; appears

(6) Large, diffuse with nucleus displaced to the Wj

suspected

just visible to the naked

еуе оп а

clear night.

-:----------------------------457

NGC 615

(10) Sтall and faint; slightly brighter towards

in diameter;

01 32.6

-07 35

12.6

2.7

х

0.8

460

те 1727

eet

01 44.6

оп

тainly

circular with

а

star

the 8.f. edge.

+27 05

12.0

1.0

х

0.5

Psc

1rr 1.

8с. Contains а very bright nucleus in а bright,

outer ring.

Meтber

of Cetus 11 Cloud.

(10) Quite faint and sтall, requiring averted

---

(1 о) 8тail, faint and fairly еуеп in brightneSs; 3 sтall, bright nucleus appears to Ье si tuated rno re towards the W edge;

х148 seeтs

elongated N-S.

----------------_.---/ 458

01 34.0

М

8c:8A(s)c. Contains 193 н 11 regions.

74

+15 32

9.33

12.0 х 12.0

NGC 628

pse ,

(3~)-T~o-a~т~ ~l~a~l; Visi~l~,-e~c~ :i;h-а- f :iРt

----

vision at first; very close to NGC 672.

461 - - - ; : ; : - ; : : - - - - - - - - - - - - - - - - - - - NGC 672

уу

338

01 45.0 8Вс.

+27 11

10.88

11.3 х 4.1

Possibly linked to 1C 1727

Ьу

an

Psc Н

1 bridge.

(16~) Bright, large, тисЬ extended alтost E-W; it

appears

тottled

and shows little increase in bright-

ness along its length;

а

dark lane appears to run

82

83

WS

Cat

RA

Dec

m

Cat

AD

CO~

(NGC 672 continued)

."S

466

along the major axis; stars lie off the N en'd, (10) Even brightness throughout; easily seen..

(8) Suspicion of mottling 462

NGC 691 !'Tkn

363

RA

NGC 750/1 уу

Arp

189 166

VI ZW 123

х121.

+21 30

13.5

-------

а

463

NGC 697

01 48.4 Рее.

+22 06

12.7

-

Nember of NGC б78

5.1

-

1.7

х

б97 group.

------------------

а

461

NGC 761

Ari

- - - -.

опе

anа

small

brighter.

side slightly brighter.

small condensation at N епа while the

is more diffuse; prolonged observation shows а соттоп

two nuclei in

lel

close to the N.f. edge.

not bright; NGC 750 larger

епа

S

bright star l'

Соп

anа brighter to the middle;

(16) Both round

(8~) х111

(1б~) Bright, well-developed centre in diffuse

AD

small spiral.

а

the NW ends in

(10) Elongated with

----

envelope of uneven brightness;

m

01 54.6 2.5 х 1.7 Tri +32 58 13.0 Е + Е. Compact cores plus bridge. А long plume to

апа

3.8 х 2.7 A~ Sb:SA(rs)bc.Member of NGC б78 - 697 group. 01 47.9

Dec

envelope.

+33 08 14.5 SBO. NGC 760, close to the

1.7

01 54.9

(1б) Round,

Ы,

х

0.5

Tri

is а аоиЫе star.

quite bright; much brighter to the

(16) Elongated in РА 1350; bright object which

middle anа а stellar nucleus; NGC 760 shows as а

slowly.brightens to the middle.

stellar nucleus anа halo joined to NGC 761.

(12) Difficult; 12~0 star close to the Ы.

(б) Faint, small; appears circular at extended at

LP but more

468

х305.

772 Arp 78

NGC

БВс.

01 464

NGC 720

01 50.5 Е.

-13 59

11.7

1.3

-----

brighter nucleus; lies in NGC 736 УГ

Zw 111

01 55.3 Е1.

+32 55

Member of NGC 733

13.5

-

а

I

+18

NGC

770, 14.2,

56~8

h

4б m

6

+18

о

er centre

anа а

lies

Б.р.

(8~)

L51 seen as

1.6

740 group.

---------------

--Tri

--

(1 6~) Elongated almost E-W; х160 and х222 tw o m~С areas of brightness appear at each end, the N аре being brighter; area between relatively dar K•

(10) Elongated; faint star оп N edge.

х б.8

Ari

very small spiral, lies at

I

(1б~) Extensive envelope surrounding а much bright-

well-sprinkled fiel d• х

а

10.5

42.

diameter wi th а muct

1.8

10.43

Cet

- .'

------ - - - -

(2i) Very difficult; about 2

465

0.7

х

Nember of Cetus I I group.

5б.

01

stellar nucleus; patchy nebulosity

the nucleus; faint star close

а diffuse glow; х102 shows а

stellar nucleus set in

---

р.

а

round, bright centre; does

not bear magnification well.

469 ~------------------------NGC 779 01 57.2 -об 12 11.3 3.0 х 0.5 Cet SBc. Spiral arms very weak

anа

poorly resolved.

(8) Very much elongated in РА 1700 - 3500; about I

2

,

х

О

.5

in size

anа

quite faint overall with

slightly brighter centre; 12 mag star lies S.p.

а

84

85

WS

Cat

470

NGC 784

НА

Dec

01 58.4

AD

т

+28 35

11.78

9.7

х

--------

- - --- --- - -

NGC 890

02 19. О

I

а у

and then to the W.

Tl'i 1ndication of а dark crescent of material n e~ the nucleus.

(10) Easily seen irregular patch of light; по sign

- - - - - - - - - - - - - -bright and slightly elongated

NGC 891

02 21.0

+42 14

10.03

-

474

NGC 93б

02 25.0

-01 22

(1б) ~uite

-

15.0 х 3.8

а

б.3 х 5.5

10.33

Cet

radio source.

bright, elongated; suddenly becomes

brighter to the middle.

Aпd

тисЬ

,

(12) Bright, easy object; about 4

- - - - - - - - - - - - - - - - - - - --,

in diameter and

very nearly circular.

(30) An enormous edge-on spiral; the dust lane is

(2%) Very faint and elliptical in shape; very тисЬ

prominent and cuts the bulge in half but is clearl:

brighter in the centre with

,

detectable only for 2

across the bUlge, being

475

NGC 949

diffic.ul t to trace further out; the disk is longer оп

+зб 55

02 27.7 Sb.

the N side.

ТЬе

а

stellar nucleus.

12.0

Tri

outer envelope is very faint.

(1б) Low, almost uniform surface brightness, being

(1б) Slightly elongated; тисЬ brighter centre.

slightly brig'hter near central region; the dark

(10) Fairly bright and elongated; easy object.

lane is very obvious across the centre; the rich star field gives an interesting 3-D effect. NGC 925

nucleus but brightens gradually in the centre.

SBO/SBa. Nucleus

Sb. Member of NGC 1023 group.

473

а

of

N.f., S.p.; brighter centre. 472

S.f. with faint

surrounding nebulosity; the f end curves to the S

el'y

Е.

(1б) Small, quite

N of the bulge.

(1б~) Brightest part elongated N.p.,

~

+33 02

Соп

(NGC 925 continued)

2.б

(10) Elongated N-S; very faint core wi th patchy appearance; а hard object.

AD

т

is visible about 3

Sc.

471

Dec

НА

Ca t

02 24.2

+33 21

10.13

14.0 х 8.б

...-Tri

Sc/SBc. Contains 99 known Н 11 regions. HS nucl eUs, Member of NGC 1023 group. DDO 25, 13~0, is at

02 Ь 30~3 +зз0 1б'.

- - - - -

--- - -----

( 30 ) Low surface brightness;

476

NGC 972

02 32.8

'cllou~

the bar is сопвр1

and shows some structure including ап elongated

х

1.9

Ari

Sa/b. Contains а very complex central bulge and smooth spiral arms.

- - - - - - - - --

-- - -- -- -- --

-

(3б) Bright elliptical shape with а mottled bulge; а

- - - - - ---

2.0

+29 13

weak

enhance~ent

is

оп

the NW side, close to the

bulge, and оп the SE side an extremely faint wisp is suspected;

по

nucleus visible.

(1б~) Elongated N.p., S.f.; the S.p. edge is

bulge with а weak enhancement to the SE; two 'ler:Y short, faint arms curve gradually from the en ds

brighter; quite large and very bright.

of the bar; some very faint detached nebuloS1't1

slightly brighter, extended central region.

(8~) х102 fuzzy ellipse with indications of а

87 86 W8

477

Cat NGC 1023 Arp

135

02 38.9

80. Radio source. An

Н

10 б8

11.6 х 4.3

9.51

+38 57

ca. t

AD

т

Dec

НА

НА

77

1 comp1ex 1ies in the '

37

region. Member of NGC 1023 group. IC 239, 121!l . t 02 h т ", another group member, lS _ _а _ _ _ _33.3 _ _ +380 45 I •

Соп

8.91

1 о. О х 8. О

Cet

PKS 0240-00. IR and X-ray source. S Ь. 3СН 71. C1ass 2 Seyfert. The nuc1eus is not ав optica1ly compact as in воте Seyferts.

- - - - - - -

(з6) А remarkable object; smal1 spiral with а

conspicuo us nuc1eus and inner ring structure, the

ated E-W; an extreme1y bright , ste11ar nucleu ~. surrounded Ьу an e11iptica1 1ens which Ь ecomess 1:

1atter being the most interesting feature, being

10ng extensions; three stars are project е d

t,.

end of the major axis; the ring is broken оп опе

-:

side; outside the ring is ап extensive diffuse

small and rather faint; х155 symmet rlcal . ova1 with а bright centre and surface brl' g ht nезs

glow containing weak spira1 features, the most

fa11ing off rapid1y towards the edges.

(1б) Very bright indeed; the diffuse halo brightens

W extension and (б)

NGC 1052

AD

т

- --- - - -- - - - - -

(1 6~) Very bright and 1arge, being great1y elo'. n

478

02 40.1

Dec _ 00 14

опе оп

the

Е.

оп

~uite we11-defined with а conspicuous knot at опе

х50

02 38.б

-08 28

Е.

radio source. Active e11iptical

Nuc~eus а

10.89

4.5 х 2.9

conspicuous being оп the S side.

abrupt1y to а brilliant core containing а bright,

Се!

galaxy wi th spectrum showing [о п] at 3727

------

ste1lar nucleus; the core contains а notch оп the S side, apparent1y а short, inner spira1 arm.

1.

(8) At LP appears as а faint, circu1ar nebu10us

(1 о) Small, faint stellar centre in faint nebul-

patch; it stands higher magnification we11, and оп

osity; suspected condensations.

МР the surrounding nebu10sity is тоге distinct; the

(8) х48 fairly large and bright and much brighter

nucleus is very sma1l and virtual1y ste1lar.

towards the centre to а stellar nuc1eus; х241 а faint star

оп

481

the S.p. edge.

:4'7::9~---:=~:-=----=----------------NGC 1055 02 40.5 +00 20 10.60 11.9 х 4.8 cet Sb. PKS 0239+002. Member of NGC 10б8 group.

( 1 о)

х59

7 mag star.

а

bit mottled.

(8) E10ngated patch of light with edge;

по

other detai1 seen.

а

oI1

12.5

10б8

5.5 х 5.5

group. SN: 1962 -

Cet

13~9.

edges аге il1-defined; becomes increasingly diff-

>

o~:

icult with higher magnification.

--.. 482

NGC

1087

02 43.8

-00 42

10.02

5.9 х 3.9

Cet

Sc:SA(rs)c. HS nucleus. 8 superassociations.

---------------------

ri

star

+01 10

(10) х59 faint with slight1y brighter centre; the

, btne

f extension appears wider than the 5. •

02 41.1

- - - - - - - - - - - - -- - ---- --

- -'

large, fain t and of fairly even brig

х148 Ы.р. appears

пеагЬу

1073

SBc. Member of NGC

(12) Extended nebulosi ty orientated ы.р., 5. f .; rather difficult due to

NGC

tbe~

(10) А fair1y easy object; the nuc1eus is ~uite large and ova1 in shape; the remainder is rather faint but an ova1 out1ine is easi1y discerned.

89 88 HS

483

Cat

Dec

НА

cat

AD

т

NGC 1090

02 44.0

1 Zw 100

SBb. Member of NGC 1068 group. SN: 1962 -

-00 27

11.98

7.9

х

-- .

(10) Excessively faint, small and oval; по nucl , е , is detectable; an 11 mag star about 1 N.p. 484

NGC 1084

02 44.7

-07 41

11. О

sc. PKS 0243-07. SN: 196з

-

-----------

2.2

х

11~2.

0.8

----....

- - - NGC 1300

487

485

NGC 1156

02 56.7

while the Е arm fades near the middle and then

I

brightens at the end near

Irr 1.

А

11.47

5.9

х

(16~)

488

of spiral structure; 2 emission patches 11 of centre,

NGC 1309

- - - - - - - - - - - - - - - - - - - - - _.-

pretty bright star is close to the W edge.

and at higher power seems elongated; higher show

по

other detail.

а

489

NGC 1332

рО

"e!S

Опе

.----/

1 е1.1 5 ' Sb. Peculiar twisted plane. Star close to nuc , "

(16~) х176 appears as round and diffuse witn а

11.4

1.4

х

Eri

1.4

arm is stronger and both well resolved.

7 mag star lies close S.p. -21 30

• Member of NGC 1315 -

Eri

1332 group,

ап

amalgam

in the Eridanus cloud of galaxies.

(8) х48 fairly large, bright and much brighter at the centre to

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ре! 486 NGC 1169 03 02.9 +25 03 13.0 5.0 х 2.8

nucleus is visible in nebulosity

-15 30

03 24.0 Е

(8~) х69 а faint, amorphous patch with а 12 mag . cl eus star in contact to the N; по d~scernable пи

stellar

(16~) Bright centre surrounded Ьу fading nebulosity;

extremely faint, extremely small knots equally

а

х176 а

03 20.9 Sb.

(36) Bright, large box-shaped galaxy with some spaced along the major axis; the underlying light distribution is weakly enhanced along the la tter''

а

which is oval in shape.

Ari

highly resol ved dwarf system wi th traces

field star;

Greatly elongated Ы.р., S.f. with faint

extensions;

5.9

а

nucleus is at the centre.

mottling easily seen.

+25 03

Eri

the bar at а sharp right angle and remains intact

the f side.

х241

4.8

knots near the ends; the W spiral arm emerges from

the minor axi s qui te broad and mottling seems

possible;

х

the bar shows enhancements, including individual

"

:rH~

(8) At LP fairly bright and large; brighter centrej х121

8.0

(30) Bright barred spiral; the bar and spiral form

area immediately surrounding the centre is mottled оп

10.58

are clearly visible, both appearing аз а soft glow;

~

quite wide; the central area is very bright andtc,

especially

29

- - - ---

(16~) Very large and bright and elongated N.f., S.

the ends of the extensions do not narrow but

-19

03 18.6

х422

SB. AN nucleus.

E:ri

-- - --

- -

(NGC 1169 continued) • bright stellar nucleus;

Соп

A.l)

т

the area S of the edge is brighter, nucleus is darker while the N.f. looking like а bright patch.

3.0

-

Dec

НА

а

а

stellar nucleus;

х241

suspicion of

star or nebulous knot S.p. the nucleus.

91 Con

90

ws 490

Cat

Dec

НА

NGC 1337

03 26.8

-08 29

s.

AD

т

- - - -

12.0

6.0

1. О

х

NGC 1465

494

---

-------

SO/a.

3 stars seem to Ье superimposed and the centre

03 32.4

VII Zw 8

Рее.

А

+72 24

'

'~

--.......

14.1

Саэ

ring encloses the nucleus of this object

- ---

-495

,

IC

356

АтР

213

--.

fairly bright star

Неэ

to galactic obscuration. (8~) Just discernable х51

not too bright

close

х102;

at higher powers;

to the N. 03 41.4

-13 35

12.0

3.0

х

0.5

496

Eri

NGC 1560

wide, dark lane runs along the major axis.

Ыо

and quite clear although

image quality becomes too poor

по

real central brightening. 11.59

+71 49

04 29.9 Sc.

SAB(rs)bc. The central parts are very complex. А

342

Саш 7.8 х 6.6 10.5 04 02.5 Sa. Radial bands of dark nebulosity cut across

- - - - - - - - -- -

I

а

bit brighter.

the NW regions. Outer spiral arms уету faint due

but the central part is faint but qui te clear at the latter power;

а

appears

(8~) Тоо diffuse to stand powers in excess of Х101

IC

Per

0.4

remainder being of uniform surface brightnesso ,

NGC 1343

NGC 1421

х

(6) Faint and fairly small at LP; at HP at least

the remainder being considerably fainter.

492

2.2

14.9

+32 24

03 52.0

AD

т

(16~) А little brighter at the centre with the S extension is narrower than the N. 491

~

E:t'i

Dec

НА

Cat

СО!)

11.9

definite nucleus. Possibly in

(16~) Elongated N.f.,

х

Саш

2.2

М81

group.

S.p.; the ends of the extenопе

(16~) Extended almost E-I'l; it widens to а bright,

sions do not narrow and the S

extended nuclear region; х351 а knot is suspected

involved star or small nucleus is visible towards

in the W extension; Y-shaped group of stars S,f.

the

-

497

р

end;

а

is brighter; an

star is visible in each extension. Саш

NGC 1569

04 28.5

Sc:SAB(rs)cd. The outer, spiral regions of this

Arp

210

Irr 1. Radio source. 2 field stars lie S.p. the

object are qui te faint,;due to galactic obScurati~t,

УН

Zw 16

03 41.9

+67 54

9.1

---------------

27.4 х 24.2

Сат

----_ ....

(8~) А small, nebulous spot about 15 _ 20" in siz UJ1dj

e

11.17

+64 47

centre. Possibly in

М81

group.

(36) Bright, large, very much extended; it appears

is all that is visible, but this is easily fo о 300, а line of 5 stars of 10 - 11 mag, РА 150 - 3

nearly edge-on and shows 4 very faint, nearly

lie about 3

est in these regions; the

,

S.p.

stellar knots along its W half, appearing brightЕ

half is faint.

(8~)x204 shows mottled areas;

S.f. end and 0

х308

appears wider at the

quite irregular light distributio

seen; BD+64 450, 9 mag, lies close to the N.

93 92

WS 498

Cat HGC 1637

-02 57

04 38.9 Sc.

AD

m

Dec

НА

1 0.75

7.7 х 6.з

- - - - - -- - - - - - - -

(30)

А

,,5

СОЬ.

El'i

NGC

1784

11.82

-11 54

5.8

х

3.7

Sc.

.Р

-

NGC 2276 Arp УIl

Lep

114

ZW 134

NGC 1888 1889 Arp

05 21.4 Sb +

-11 30

ЕО

1.4

х

0.8

3.5

х

1.1

(16!) NGC 1888 is slightly extended N.p., S.f.; it а

well-developed eentre with short

,

Саш 4.0 х 4.0 11.54 +85 50 07 19. о Sc. А bright, very knotty arm lies оп the W side. 4 superassociations. SN: 1966 - 16~9, 1968 - 15~7, о ' h 16~6. NGC 2300, 12~2, is at 07 15~7 +85 48.

visible at х176. NGC 2403

07 34.4

+65 40

8.48

29.0 х 15.0

Саш

Se:SAB(s)cd. Radio source. contains 109 н 11 т h т regions. SN: 1971 - 1 6 .0. NGC 2 4 04 , at 07 32 .1 ' +65 о 48, is а bright knot in the galaxy.

- --- - ---

123 shows

..

the centre; resembles а puffy cloud; по nucleus is

504

Lep

- - --

- - - -

(16!) Large, round, very diffuse and brighter in

(10) Appears almost circular at LP and at HP sligЩ

500

СМа

2.0

- - - - - - - - -- - -- -- -

close S.f.

brighter towards the centre; edges ill-defined.

х

f ,. very difficult at higher powers due N ., S in part to low altitude.

- - - -.

faint star is close S an

14~6.

3.0

with slightly brighter centre; а little extended

(16!) 1rregular shape; х176 the centre is extendedj а

-

11.8

(10) х59 faint and fairly uniform in brightness

bright asymmetric spiral; the central

05 04.4

SN: 1975

- -- -- - - - - -

- - - -

(16!) Quite bright, slightly exiended and Ь rlghter . to the middle

-21 21

06 14.4

s.

502

" l'egi o. is bright and round but has по nucleus' surr ' •• • ' 01lb. di n, th1S lS а fa1nt, slightly oval glow about 1 _ ,~ . d' 1.5 1П 1ашеtеr from which а spiral arm emerge s оп th e W side and winds about 900 until it points Е.

499

NGC 2207

Dec

НА

cat

Соп

AD

m

narrow

(82) Very large so that the large scale-structure is difficult to see; х820 definite signs of partial

extensions; х351 the eentre is extended and the f

resolution into individual stars in some of the

edge is straight and sharply defined. NGC 1888 is

brighter knots. (30) А magnificent spiral with knots strewn all

almost stellar with

а

brighter eentre; the area

between it and NGC 1889 is dark and sharp.

::----=~~---:-:------------01 NGC 2146 06 14.7 +78 22 10.68 8.4 ~ 4.8 Саш Sb рее. 4С 78.06. Optically disturbed. NGC 214

,

lies 19

N.f.

6А

---

(16!) Elongated N.p., S.f.; the centre is wid e extended; х176 mottling and а dark pateh р the centre; х351 the ends fade at the extremitie s •

~d

over the field; more than а dozen are visible, mostly in the outer extremities; two spiral arms are visible, the brighter winding NW from the S side and then curving Е; two bright knots are near the end of this arm, опе being NGC 2404; the other arm is very low in surfaee brightness, and has ап extremely faint enhaneement; the central bulge is mottled and quite extensive.

94

ws

Cat

RA

95

Dec

AD

т

(16~)

At first sight resembles

.

М33.

th

'

IC

е cel1t:ra

~ s well-developed and i s а l i ttle bri ht а nebulous knot (NGC 2404).

2233

tb a . , !l tt;

v~s~ Ь1

х50 а

large, fairly bright, shapeless

р

elongated and slightly pointed at the р el1d small vacuity just visible оп the S side. 505

NGC 2537

vv

138

Arp

6

Mkn

86

08 11.5 S

+46 04

12.3

рее.

1. О

х

0.7

а

t

е Рl,

р ив а

(36) Small and of

- - --1

08 12.2 SB(r)bc.

(16~)

Lyn

-

508

+73 39 А

Uma

bifurcated arm emerges from the NW end

Shows

а

small core in diffuse nebulosity; the а

NGC 2549

08 14.9

S~

+57 57

12.5

1.5

х

0.7

Lyn

outer lens shows traces of brightening at the ends. (8t)

509

Slightly brighter centrej faint extensions.

NGC 2608

08 32.2

Ахр

SBb/SBc. Contains а double nucleus or а single

12

nucleus and

-

+28 38 а

12.9

1 7

х

Сnс

0.7

superimposed star. The W spiral arm

11~8.

(16) Dim, fairly elongated; slightly brighter centre.

510 ~-------------------------NGC 2613 08 32.2 -22 53 11.3 6.0 х 1.9 Рух

of

circular shape; near the centre is а large, dark ar

х

12.4

divides into three branches. SN: 1920 -

bar feature. el

and а small, bright spot is excentric towards tbe N.f' edge·, а Ь' h '1er1 r~g t star lies S.f. and а fainter star close to the f edge; i t rather resembles nebula such as М97.

star lies close to the N extension.

SO/E6. Contains а bright, elongated nucleus. The

side; this ring-tail includes 3 knots, оnе of about

anа

Lyn

dark area is seen around the centre, being more

single spiral arm winding from W to Е around the N 15 mag; а bar-like feature shows in the interior region of the arт and extends to the S edge of the galaxy; there is а faint glow between the arm aJld

6.7 х 1.3

outer nebulosity is variable in brightness and

- - - - - - - _.

strange object, bright, quite large

а

pronounced to the

re ati vely high surface brightness; shaped like а Ьеаr-paw, th е structure consisting Ofl

(16~) А

12.64

of the bar structure.

,

"Bear-paw" galaxy. The largest associated НII region is about 200 kpc in size. Member of the NGC 2841 group.

------

+45 53

Соn

AD

Extremely narrow and very long, being aligned

almost E-W;

ch· I€'

l'

m

of the flattest known galaxies.

Оnе

(16~)

(8) Fairly bright, very extensive but diff about 1000 Usej Рл and 2 stars are superimposed 011 tb W sides; по nucleus is apparent but th еЕа.:: ere аРреа denser portion in the middle and an аХ' t 1'В, С О tbe W almost like а spiral arm. ' (6)

08 10.4 S.

1 С:

еХ'

g

rest of the galaxy; two spiral arms are

Dec

НА

cat

(NGC 2403 contined).

а рlaJlеtФ

SA(s)b. (16~) Very elongsted N.p., S.f.; а bright centre is

visible in extended lens and appears wider;

х351

а

х176

the f extension

nebulous knot shows

оп

the S

edge of the f extension and there is also оnе f the central lens.

96

97

ws

Cat

511

RA

Dee

AD

т

NGC 2683

08 51.2

+33 38

Sb/8e. Contains

(8) Faint, very elongated and mottled; х241 Ь s 0'( eentral brightening and the N .р. extension е е а

Dee

cat

(NGC 2613 eontinued).

out to

RA

а

9.72

NGC 2639

08 40.1

+50 24

11.6

1.0

8а/8Ь.

I

х 0.5~

to extend for mueh of its length.

(16~)

i s Бе~

Arp

80

225

рее.

- ---

The nucleus is

(18) Large, round

anа

а

-----

---.....

08 47.9

511

very diffuse; despite the а

Arp

Е

167

+

сотр.

12.2

The companion has

extending to the

а

0.4 а

NGC 2685

Arp

very

зз6

Е.

diffuse centre. х

----- -

518 -'

а faint, nebulous knot anа eould Ье mistaken for

515

NGC 2681

08 50 •. 0 8а.

the f

епа

of NGC 2672.

----Ul'!3

5.4 х 5.4 Contains both inner and outer rings. Jl'!е тье! +51 31

10.65

о!

.1

weak surrounding nebulosity. (8) Circular with а stellar nueleus; hazY е

ce~"

ages ,

UМa

small апа elongated N.f., 8.р.;

bright star lies elose

NGC 2692

08 55.2

extended nebulosity; по detail.

+52 10

14.1

1.3 х 0.4

Шlа

90 " Ы.р. is an Anоп. spiral, 13~6.

(8~) Very difficult,

----

ы.

diffuse blur;

по

appearing аэ а featureless

sign of the

Anоп.

spiral.

519 - - - - - - - - - - - - - - - - - - - - - - - NGC 2713 08 54.7 +03 06 12.9 4.1 х 1.4 Нуа 8ВЬ.

2 filamentary arms form an outer ring.

8Ы: 1968 - 14~3.

NGC 2841 group.

(16~) Bright and eircular with а much brighter

5.5 х з.6

рее.

8В.

encloses а stellar nueleus; the companio n shoWS as оп

8

11.38

+58 39

(8~) Quite faint,

(16~) Bright, irregularly round; the bright centre

star; it lies

08 52.2

а

Cnc

0.3

long streak whieh looks mottled

the central area is extended along the major axis;

faint, curved plum e

------ - - - -

а

а

shows as

(16~) Quite bright,

+19 10

an

mottling is eoneentrated around the centre.

slight elongation.

NGC 2672

Ье

along its entire length; х111 the majority of the

Саш

- - - - - - ..

latter it is quite bright; indieations of

514

.

brlghter

Bright, very elongated and of high surfaee

(8~) х56

strong radio source.

(6) Nebulous glow brightening to

а

brightness in the cen'tral region; bright eentre.

7.7 х 6.2

10.16

+78 19

I

1 ; displays

seen in the 4-ineh finder.

(8~) Faint oval with slightly brighter eentre. 08 52.4

х

indentation; the N edge is more diffuse; easily

(14) 8pindle elongated E-W; а bright eentre

NGC 2655

Lyn

3.9

centre and N of the nucleus there appears to

- --- - -- --- - - -- - - - - ---

513

х

shaped nueleus and possibly an outer ring. (18) Visually about 6

512

12.1

Соп

small, very bright peanut-

Jcte~,. '.

bright star.

AD

т

(12) Oval nebulosity lying Ы.р., 8.f.; bright centre; the supernova observed 8.f. the nueleus.

99

98 WS

520

NGC 2719

08 58.7

Arp

Рее.

202

а

0.3

NGC 2841 continued) outer areas appear hazy and

,,5

Ly!\

- - - - оп

1 ittle brighter

09 09.0

l~

the NE edge.

Sa:SA(r)ab. NGC 2777,

а

тottled;

а

10.7 m

.,

stellar nueleus;

NGC 2782

09 10.9

2. 1 is at

-----09h08~4 х

1.2

х241

+07021'

а

litt:

Arp

Sb

215

рее.

HS nucleus.

11.7

1.8

Reтoved froт

х

1.8

star out of focus; easy object.

-

NGC 2872 2874 307

Lyn

Seyfert class.

523

NGC 2787

09 14.9

9 mag star lies 5

+69 25

10.9

3.5

2.3

2.2

х

0.7

Leo

Position given is between the two. 2872 is а Seyfert, 2874 is distorted. NGC 2871 and 2875 clo~ are stars.

------

-------

shape with РА about 1100. NGC 2873

(18) Egg-shaped galaxy with bright nucleus; two and

1.8

siтilar in brightness distribution but is oval in

UMa

,

- -. оп р

х

тiddle to а stellar nucleus; quite small; 2874 is

SBa.

faint stars

+ Sc.

2.0

(16) 2872 is quite bright and much brighter in thE

to the N. х

Е

+11 34

- - - - -

I

а

09 24.2

Ьу

(б) Shows а slightly brighter centre in round

nebulosity;

- - - -- - - -- - -

stellar nucleus. (8) Sтall, round with bright centre; rather like

СIlС

- - - - - -. appears

LМi

(1б) Bright, round and much brighter to the middl

bright star lies to the W. +40 19

dark section is

1.9 х 1.2 10.7 +34 38 09 22.8 SBc. Contains а weak, diffuse outer ring.

---------

"

Arp 522

2859

525

(8) х48 fairly bright and mueh brighter at the eentre to

~NGC

S.f

х222.

+07 09

а

suspected near the centre.

small and elongated N.p.,

appears bi-nuelear NGC 2775

х

Соп

AD

m

Dec

RA

cat

СО!)

Double galaxy 40" apart; the N eompOneIlt,'

(1б~) Very faint,

521

1.3

13.5

+35 49 Disrupted.

- - - - - (БО)

AD

m

Dee

НА

Cat

S.f.-еДgеs.

stellar and about 2

527

NGC 2903

N of 2874.

+21 з6

09 30.7

appears almost

9.01

13.9 х 9.0

Sc. PKS 0929+21. HS nucleus. 74 known

(6) Oval with sтall, stellar nucleus.

Н

Leo 11

region~

NGC 2905 is part of it. А sтall, interacting grOU]

,

524

NGC 2841

09 18.6

+51 12

9.38

Sb. Radio source. SN: 1912 1972 -

of galaxies lies 33

11.3 х 5.7

WSW.

------

13~0, 1957

( 30 )

1б~0. Member of NGC 2841 group. 'S

(1б~) Elongated N.p., S.f.; а stellar пuсниэ J.

, o!lS

Four-arтed

split into 3 sec arтs emerge; the

----

· 1 w;th weak bar, the latter sp1ra ~ ' at each end of the bar 2 t 10пв;

arтs оп

the

ЫЕ

side are shortes

t

тottled while опе of the SW arms fades

seen in а bright lens froт which broad extensJ. . 1e1.l$· p01nt; а possible sтall, dark area р the риС

although

(8~) Stellar nucleus in extended nebulo sity ;

round and non-stellar.

tpe

------

he nuclear region is appreciably par t way aroun d ; t

!

101

100 WS

RA

Cat

Dec

m

Cat

AD

NGC 2976

(NGC 2903 continued).

5,1

(16~) Elongated N.f.,

s.p.; the nuclear r . . e~~! brlght and extended and considerable dark S . mottli 1 s seen around i t; an arc of bri gh t nе bul . ~€ ОБНу

nеа!'

the end of the N extension and а similar occupies the 8 end.

AD

m

Dec

RA

Соn

UМa 3.2 х 1 .1 11.4 sc. The inner structure is quite chaotic with а good nuшЬе!' of dark lanes. МетЬе!' of М81 group.

09 43.2

+08 08

- - - -- -- - - - --

(16~) Elongated N.p.,

SQQ''

S.f., with а diamond shape;

х333 brightness variations are evident plus а sta1'

а!'е.

01' nebulous knot N of cent1'e.

(8~) х53 а diffuse, nebulous glow which gradu 1 а ly

(8) Еуеn b1'ightness; х152 slightly mottled with а

b1'ightens towards the middle and

suspicion of а sta1' оп the edge of the 8.f. end.

а

stellar nu 1 с ells. dark patches highly suspected nеа!' the nucleus', '

(6) Faint, nebulous glow without anу nucleus.

. the nucleus is elongated and the dark r eglo ns still suspected; РА 300 - 2100. х212

-

(6) Oval nebula with diffuse, oval nucleus. 528

NGC 2911

+10 22

09 31.0

13.3

4.0

х

М

-

3.0

А

star lies 25 "

Н.р.

the nucleus.

81

UМa 7.00 35.0 х 14.4 +69 18 09 51.5 8Ь. Contains relatively few large emission nebulae.

Nucleus is а radio source. Enveloped in an Н 1

Leo 8. Contains compact radio sou1'ce. Seyfert-like spectra.

NGC 3031

envelope with NGC 3034 and NGC 3077. DDO 66, is at

09h53~5

13~7,

+69016' •

- - - - - - - - -- --

МетЬе!

(30) An enormous central area evident but only one

of NGC 2911 - 2919 group.

spi1'al a1'm; the main problem is the size of М81, as (16) 8mall, round and brighter to the middle; the close companion, NGC 2912, at 09 h 31~1 +100 09', was not detected. 529

NGC 2964

09 39.9 Sc.

11.38

+32 04

РК8 0939+32В. иkn

- - - --- - - -

404 is

4.3

х

anНII

the obse1'ved (8) arm has two faint knots and is patchy near them; the central bulge has а small

Leo

2.4

concent1'ation near the centre, with а bright peak.

region in it.

- --

------

structure seen in the o u t e r' reglons, this bel'ng IJIos оп

sky because the field of view is not large enough;

-

(16~) Oval with а stella1' nucleus; х333 а ring- like

definite

the faint outer parts have little contrast with the

the f side.

(16~) А very bright,

with wide extensions; there are 2 b1'ight stars in i

:-::------::::~:-:::-------------~ o

530

NGC 2968

09 40 • 2

+32 09

1r1'. 8Ы: 1970 -

(16~)

11 .9

1.2

13~0.

Quite b1'ight and circula1';

is sur1'ounded

Ьу

а

dimme1' nebulosity.

х

Le

0.7

-

- - l1tre

b1'ighter ce

well-developed co1'e is seen

the f extension beyond which the nebulosity cu1'ves and brightens; the N extension widens fu1'ther out. (6) х183 the 8.f. extension appears а little mo1'e bright than the N.p. оnе; suspicion of а dark lane running parallel to the major axis оп the f side of the nucleus,which is stellar in а bright core.

102 \oIS

533

Cat NGC

1"1

Arp

3034 82 337

НА

т

Dec

103

AD Cat

+69 56 8.39 13.4 х 8.5 1rr 11. 3СН 231. А number of infrared 09 51.9

NGC 3077

- - - - -- -- - ---- - - - --

-high; th

NGC 3115

of dark bays are visible along it

2.0

М81

а

UМa

Seyfert

group.

_

-----

-07 35

Deep plates show

тапу

Х1,

Ь' r1ght

, oval material;

globular

- - - - -

4.0

9.3 а

х

1.0

Sex

strong halo component and

~lusters.

Suspected SN - 1935.

------ ------ ------

(з6) А perfectly edge-on lenticular galaxy with а

р edge; а nuтber of bright knots are visible, twoc: them being positioned each side of the main Ьау,

compared with the length.

(6) The dark absorption lane near the centre appear!

(16~) Very bright centre with narrowing extensions.

as а wedge-shaped intrusion from-the S; оnе or t~ more dark bands suspected towards the f end, which

bright central core; the width is very narrow

5~7

u

05459

diffuse glow fans out from the centre оп the S side,

of nebulosity extending from

+32 36

-----

- -.

-------------

(10) х59 faint, slightly brighter towards the centr: and somewhat extended; х148 а thin, edge-on objeC t

х154

5}8

NGC 3166

--

- - -

(10) Edge-on, wispy and

UМa

it displays

еуеп

а

7 mag

star;

х111

surface brightness with

and

по

10 12.5

+03 33

11.4

5.0

х

2.8

Sex

(16) Very bright an d very much brighter in the

1О • 59 11 • О х 2. 3 UМa Ь ; t d;[fi cu1t ' а sorp t 10П таk es..L

middle to

а

brilliant nucleus.

..L

to see the central region

- -

0.5

Sa/Sc.

- -3079 -------------------_.--' 534- - -NGC +55 57 Sc. 4С 55.19. Strong

х

nucleus being apparent.

-

aligned N.p., S.f.; х296 по change.

09 58.6

4.3

+53 20

(8~) х77 just visible as an extremely faint streak

12.7 2.2 х 0.8 1ео h Sa/b. The 15Т8 QSO 3С 232 is at 09 55T4 +32038', 09 55.4

10 04.8 S.

тау explain why the р part appears brighter; а fain:

3067

thought. Member of

10 04.0 Е.

s

closest to the centre being wider as i t reaches the

NGC

х

emission-line galaxy, not

(8!) Ellipse with strong central condensation.

length, all being highly inclined to the maJ'or а'

533

3.0

Соп

dark areas seen in the outer parts.

eSe are very faint, but two are pretty bright; anoth , e much weaker dust lane is оп the NE side. "

the two most prominent are f the centre, the Оnе

10.9

, (16!) Stellar nucleus seen 1П

knots are near it, 4 оп either side; six of th

(16~) А number

опсе

AD

т

+68 58

А N ormal

as was

" e dt, lane at the centre is very strong, and at 1east 8'

Dec

09 59.4 1rr'.

are distributed within. Member of М81 group.

(36) The surface brightness is qui te

НА

оп

(8) Broad minor axis; slight mottling at (6) Oval with hazy nucleus.

photographs.

- - - - --

~li ttle

brighter

сеР tr e•l~s

(8) Extended N-S; х241 а star seen in the N the possibility of slight mottling.

ера Р

хз62.

s;;--------~-------------::-:-:-:--s::-:e=x~ 3169 10 12.9 +03 з6 10.54 6.1 х 5.1 NGC

Sa. Distorted. Member of NGC 3166 group. (8~) Elongated fr\

n';_':1 __

+n

bright centre and uneven light. .;th L hh п 71 // '-,,+ blitl1 nn npfinitp. nucle1Js.

W r.II

104 WS

Cat

540

NGC 3185

105

НА

10

Dec

16.з

+21 49

m

AD

12.20

arms fo rm _Sa._ Weak _ _ _ outer _

ап

cat

3.9 х 2.6

NGC 3193

t ех ernal rillg.

уУ

------------

307

(10) Hather indistinct; по ap~arent

' nucleus Ь brighter in central area; slightly ext 11\ ellded (8!) Qui te di ffi cult; shows as а spindl • , е аЪ Оut 2 х 1 in size. NGC 3184

(6)

- -----

(16!) Slightly brighter llucleus wi th N • f. i t ; х2 2 2 а

~

а star cl

star оп the N edge wi th а dark

уу

Arp

209 94

ОЗ:

NGC 3187 уу

307

Arp

316

10 16.4

+21 59

13.27

4.3 х 1.6

546

Arp

уу

3189 307

Sa. Contains

а

5.9

х

2.4

small ghost image?

+20 09

13.3 Possibly linked to NGC 3227

(16!) Bright

round; being rather

х

3.0

2.5

Ьу ап Н

Leo

1 flow.

aпd circular with brighter centre.

+20 07

12.2

х

5.0

4.5

Leo

(16!) Elongated Ы.р., S.f.; it has а stellar опе

reaching

to points. (8~) Brighter aпd larger then NGC Ъrightепs

-----

Le o

-

547

NGC 3245

(10) Strongly Oval-shaped; the nucleus is brig!J

а

small, bright

10 25.9

+28 38

11.2

2.9

х

1.8

(8~) Bright centre with stellar nucleus;

...n:. "

t . . r eS'ех ends lnto thin arms; х222 а very strong llJJP

of а dark laпe S of the centre.

towards the middle where

Leo

Sa.

the ..

stellar nucleus is surrounded Ьу а bright leI1S

3226; gradually

nucleus is placed.

---

(16!) Very bright and elongated Ы.р., S.f.;

oval and the N edge appears brighter.

Е.

а

aпd

almost to NGC 3226; the extensions do not narrow

very bright, condensed nucle uS ,

-------------

Ы.

very small, faint

10 20.7

bright star lies

nucleus with bright extensions, the N

- - - .' (16!) Very faint, large and elongated; best image

11.10

х82

а

Ьу а

Sb. Seyfert. Nucleus radio source. X-ray source.

209 94

------

+21 57

bright central area is surrounded

vv

S. Distorted. Ыо definite nucleus.

10 16.7

Leo

10 20.7

Leo

(8!) Spindle; slightly brighter centre. NGC 3190

4.6

NGC 3227

at х222 aпd when NGC 3190 is out of the field.

5435

х

4.8

brightening.

(6) х61 quite large though pretty faint; circular

542

11.02

Соп

(8~) Uniform brightness with а very sudden central

area to the S.

i n shape wi th gradual central brightening; х152 а star is close to the nucleus aпd at higher роwеrз the galaxy is very difficult.

А

diffuse it appears like NGC 3226

AD

Е2.

just to the

---

------

m

region of mottled nebulosity;

+41 33 9.84 9.5 х 9.~L еО Sc. Contains 56 н 11 regions. SN: 1921 - 13~5, 545 11~0, 1937 - 13~5. 10 16.8

+22 01

10 17.1

(16!)

.t'

541

Dec

НА

t;

seems а

little brighter along the major axis.

;;------~---------------------NGC 3310 10 35.7 +53 46 10.1 1.5 0.8 UMa х

Arp

217

Sb

рее.

Nucleus radio source. Spectrum shows strong m UV continuum aпd emission lines. SN: 1974 - 16.5.

(36) А fascinating object; the nuclear region looks

106 WS

107

Cat

НА

Dec

AD

т

НА

Cat

(NGC 3310 continued). like а small cluster of knots or nearly

t

о bjects, arranged like water droplets in

S

NGC зз68 ell

м

"t'

96

Dec

1 О 44.2

+12 05

Sa. Member of

М95

10.8

nucleus of about 11.5 mag;

short pointing NE and а small, very faint diff .

seen to

(8~) х69

оп

the opposite side.

(16~) Very bright and round; х84 it resembl

es a.n unresolved globular cluster and х176 the с . ore 18 well-developed within the outer envelope. (8) Small, quite bright, bluish; slightlyel approximately 80

о

7.8

Leo

quite bright, large and elongated in РА

1200 - 3000; the nebulosity brightens towards а

а "е

knot

Соп

х

group.

. . а srn"l rlng-llke structure; there тау Ье а very I sffiall nuclear knot off-centre in the ring· out . , slde th ring there is weak structure, consisting of е 1I8е

AD

т

-552

NGC 3377

Ье

NGC

the nucleus is

slightly elongated or

10 45.0

Е6.

х111

+14 15

3377А

10.5

= DDO 88 is at

еуеп

1.5

х

10h44~7

double. 0.8

Leo

+14020' •

(14) Elongated N.f., S.p.; а stellar nucleus is seen in bright surrounding nebulosity which ends

~~

and feathery at the ends of the

in slight extensions.

major axis; centre brighter.

549

(6) Small object wi th 30" diameter nucleus; very

NGC 3379

10 45.1

like а planetary nebula in appearance.

м

Е.

9.3 х 6.4

105

+12 50

Member of

М95

9.6

4.5

х

4.5

group.

NGC 3351

1041.3

М

Sb. 3С 245. HS nucleus near 7 emission regions

axis aligned almost N-S.

14 " in diameter. Member of М96 group.

(8) Stellar nucleus; edges ill-defined.

95

+1158

9.76

(12) Oval nebulosity with brighter centrej major

Leo

- - ."

(30) The bar is а weak extension from the bulge,

Leo

554

NGC 3384

extending E-W; outside the bar the iпner ring fo!s

10 45.6

+12 53

10.2

3.0

х

2.0

Leo

SBa. Member of NGC 95 group.

is suspected, but only wi th great difficultYj the e ring resembles а pair of spiral arms, since it do :

not qui te close and appears brightest to the S; по nucleus is visible in the central section. (8) х48 Large and bright with circular shape; а. stellar nucleus is seen х121 plus some mottling; по

550

change at higher powers.

NGC 3353

10 42.2

Мkn

Рее.

35

+56 13

~

13.0

-------

1.4

-

х

1.0

-

type nucleus; mainly circular in shape.

555~----------------------NGC 33В9

10

45.В

+12 47

(10) Rather small, fairly bright and ro und

, SE.

12.5

2.0

х

0.9

Sc. Contains very blotchy arms. SN: 1967 (В)

Leo

13~0.

Quite large but faint with еуеп light; х121

seems rather circular and is slightly brighter at the centre; at higher powers appears mottled and slightly extended E-W.

- - -

distinct nucleus; 11 mag star about 1

vмз.

(8) х48 Fairly large, bright and shows а stellar

109

108

WS

556

Cat

RA

NGC 3412

Dec

10 48.2

m

+13 40

SBa. Member of

1ео

х

2.5 1 cloud.

RA

cat

AD

NGC 3445

1.3

УУ

- - - - --

Arp

14 24

(16) Bright spindle elongated approximatel

• у N,S much brighter in the middle to а stellar nucl i а

557

NGC 3414

Arp

162

faint star almost in eontact wi th the N ed

10 48.5 8ВО рее.

+28 14

11.0

е"

ge,

"

561

+57 15

Соп

х

1.2

UМa

1rr.

(10) Diffuse; not much brighter at the centre, 10 52.9

in

- --

in diameter; weak nueleus.

1.2

1.4

+57 23

0.8

х

UMa

(10) Rather faint, small and round; stellar nucleus;

2 faint fan-shapes extend from the

,

10 51.5

AD

т

80.

1.8 х 1.0 ~

centre region through the outer halo.

(12) 2

- - - - NGC 3458

Dec

-

NGC 3504

а

3

barren field; 10 mag star about

11 00.5 8ВЬ. РК8

I

8.

+28 15 10.9 2.0 х 1.0 1104+28. Peculiar nucleus.

1Mi

(8~) х56 а moderately bright oval of nebulosity

wi th very slight eentral brightening;

125 0 - 3050., hl'gher powers s h ow

по

РА

(10)

about

more.

х59 fairly bright and gradually more so near

the centre to

а

stellar nucleus;

х148

extended

Ы.р.,

8.f.; х296 а faint star just off both ends.

558

NGC 3430

IC

2613.

10 50.8

+33 05

4.5

х

LМi

2.4

NGC 3521

8e:SAB(rs)e.

+00 15

11 03.3

Sb. The nucleus is (8~) Defini tion diffieul t

559

уу

Arp

11 206

а

х

7.0

1ео

radio source.

owing to а nearby 8 mag

star; 1Р shows faint, irregularly-shaped nebulosi '\

(18) Quite bright but difficult to decide оп anу

of low surfaee brightness; ИР shows elongation in

structure; appeared fuzzy, very elongated and with

РА 350 - 2150 plus indieations of nuclear bul~.

diffuse edges.

-------------------------------------NGC 3432'

13.6

10 50 •.8 +з6 48 11.28 8.2 х 2.4 Leo 8В. А dwarf eompanion lies elose to the s\{ end.

Member of NGC 3184 group.

d1e

.. W~:..

(8t) Тhe ЫЕ end appears wider and is cut_o~\: srJl о о ро).п , Р А 90 - 270 , the SW end tapering to а lе" nuc faint but definite mottling is apparent; па ; iJlS (6) 1arge, rather faint nebula which сап ta. а

56;"4-::-::-------------------NGC 3556 М

108

+55 57 Sb. БЫ: 1969 - 16~0 •

ора

qU e •

10.12

11.1

х

4.5

UMa

----------(30) Dusty edgewise spiral; по nucleus, but ап elongated patch near the centre; at least 4 other knots visible, the 2 brightest being at opposite ends of the galaxy; dust is obvious

(16t) The centre has either оп

douQle.

(5) Bright, large, elliptieal; very

envelope around very bright centre.

11 08.7

---

(16) Bright anа slowly brighter to the mid , d W en • extended in РА about 350; 2 faint stars a t S ')1

stars, 2 of which form

(8t) High surface brightness with very extensive

i t or

with

а

а

а

оп

the W side.

small, bright star

stellar nucleus; appears very mottled

nebulous knot

оп

the

р

extension while the

11

О I

111

WS

Cat

НА

Dee

m

AD

cat

(NGC 3556 eontinued).

NGC з628

11 19.0

N end of the following arm is also brighte

уУ

Sb. Nucleus is

(8~)

Extended wi th patehy areas to

Е

a.nd

308

11 12.0

+13 05

12.0

5.0

difficult to see

(16) Elongated and quite bright eentre', n

566

NGC з623 1-1

Arp

65

317

11 17.6 3а.

+13 14

Nucleus is

а

по

9.37

-

а

faint star lies close

Е

-

оп

М

66

Arp

16

+ 13 44

9.02

the W edge. HS nucleus.

very bright central spot; the outer halo quite faint (6) Faint, circular with stellar nucleus.

of the nucleus. NGC 3646

extensions to а brilliant, extended eore

Whl

dominated Ьу а circular nuelear region an

а

Е.

(8~) 1arge and very bright; the eentre gra х212 а dark lane is suspected Е of the

п 11

the ring;

е

l eu • C

3.7

1ео

an elliptical, some-

а

оп

the N side;

dozen knots or enhancements outline conspicuous nucleus is a't the eentre.

(1б~) А large nucleus in ап elongated lens of ~

stellar nucleus slightlY N.р. s

а

about half

jS •

ce~~

Ьу

closed and is knotty, espeeially

н:

du a1lY

х

what pointed ring structure; the ring is eompletely

ste11i>

nucleus; а spiral arm leaves the main ьоау

5.0

рее.

central bulge is surrounded

~

to tb

11.28

(36) Bright, with ап unusual appearance; а diffuse,

13.8 х 6.5

. сl1

+20 19

11 20.4 Sc

(16) Extended approximately N-S; diffuse, irregu·

а

UMa

(14) Quite round, showing а brighter middle with а

stellar

------------ -

brightens to

10.45

axi;

Leo ns 3Ь. Н3 nucleus. PKS 1117+132. 25 Н II regio , .

S and curves off to the

+53 19

7.2 х 7.2

3c:SA(s)c. Contains а very large superassociation

27

------------------------------------11 18.9

very

Arp

of the background sky. NGC з627

а

11 19.6

1ео

(8~) А dark lane i s vi si Ые to the W of the nucle~ 510 extending for abou t 2 I .5; i t i s seen as а darkeni~

567

photographs.

NGC з631

(16) Very large and bright-; elongated centre 'йНЬ nucleus;

оп

S side appears more sharply cut-off.

------. а

11

(8) Only very siightly brighter in the eentre; the

о

radio source. Distorted major

circular nuclear region surrounding

Н

brighter to the N.

-.

11 • 9 х 4. 5

radio souree. 8 known

1ео

most of the length; the eentral region ia much

а

эееп.

nueleus

4.3

broad and obvious equatorial dark lane runs along

еО

nucle:, (8) Small, faint, possibly elongated in РА 600,,

looks like an elliptieal;

х

18.0

9.53

Ссп

(16) Very bright and extended almost E-W;

х 2'3~1

30. Contains large amounts of dust. Probabl у member of м66 group.

+13 44 а

AD

m

regions. strong absorption makes the centre

:t'.

W ог

the eentre, the former being the bright . estj the Е end posslbly somewhat wider. NGC 3593

Dee

НА

571

lesser surface brightness.

---------------------NGC 3665

11 22.0

+39 02

1.0

11.4

х

0.8

UMa

Sa. PKS 1122+39. Strong absorption at the csntre.

- - - - - -

----

- - - - - - - - - --

(8) Quite bright with а glowing nucleus and diffuse outer area; too faint for

НР.

112

113

WS

572

Cat NGC 3675

НА

Dec

11 23.5

m

+43 52

10.6

AD

Cat

3.0 х 1.0

NGC 3729

Sa. Contains а strong absorption lane. а

member of the

СУп

11 cloud.

--

+58 49

1С

694

Рее.

уу

118

and possibly

Arp

296

Mkn

171

12.0

х

1.4

suspected with

. '

Соп UМa

nucleus in an oval glow;

the

Е

side, with

а

а

faint arc is

dark interior;

а

оп

faint star

the S side.

а

а bright,

bright patch clos,

to the end of the S extension. (6) Bright and small; а star is оп the S.p. edge •

(60) Two objects in contact; а short extension is have brighter, extended centres.

а

оп

weak bar is

couple of extremely faint knots

extended nucleus is seen plus

or d"'arfs E-type. Dust in abundance.

to the S and а slightly longer опе to the N; both

а

а

(16~) Major axis aligned almost E-W;

4

..

objec~s

4.6 х 3.1

and

is attached

~

0.4

Consists of 2 large systems + 3 опе

11 .41

(30) Pretty bright and small;

re ln fainter elliptical envelope; 56 Uma, 5~0, 40' р, 1126.0

+53 16

AD

SB. Distorted.No definite arms in outer areas.

Jnldd О О ( 8-2~) РА 170 - 350 " ь right, extended cent . еi

NGC 3690

11 32.5

m

- -- - - - -- - - -- - - - - - - - - - -

(16) Very elongated; bright with brighter

573

Dec

НА

511

NGC 3738

11 33.1

Arp

1rr.

234

11 .8

+54 48

1.1

х

UМa

0.7

(8~) Shows as а nebulous patch х51; х204 appe~B

as patchy and mottled wi th

а

(14) Small, round and very f~nt; а brightening

brighter section at

of the middle is glimpsed but nothing else; does

the W end which is pointed, the remainder of the а

material extending in 574

not stand higher powers well.

fan-like shape. NGC 3810

11 38.3

10.8

+11 45

4.1

х

2.8

Leo

11 29.9

Arp

SBb. Narrow absorption lanes cross the centre.

Sc:SA(rs)c.

(60) Very faint; suspected to Ье bi-nuclear.

(8) х48 fairly large and bright with а slightly

(16~) Slightly extended N.f., S.p.; а bright,

brighter centre; e10ngated N.f., S.p.;

214

+53 21

11 .2

3. о

х

3. о

Uma

- - _ ...

elongated centre with lies

оп

the

Е

а

brighter S end;

а

11 32. О

edge.

+47 10

11.7

4.6 х 3.5

(16~) Elongated with stellar nucleus; х175

outer nebulosity mottled

curving arm runs from the S to the of the arm is darker.

а

suspicion of the f end appearing

there

little

579""-----------------------

Sc. Contains very patchy spiral arms.

N edge;

а

х145

brighter.

- - - - - - - - - - - - - - - - - - - - - - - - - -Urna NGC 3726

is

star

(6) Faint with по nucleus. 575

518

NGC 3718

Е;

---

NGC 3877

11 43.5

Sc.

А

10.9

+47 46

star is superimposed

4.4

оп

х

1.8

Uma

the nucleus.

(10) Irregular shape; patchy in parts with по definite nucleus;

а

13 mag star lies close

р.

(8~)A quite bright streak in РА 400; а good, I

bright nucleus in the 2

-

3

long nebulosity.

(6) Spindle with large, faint nucleus.

115 114

Cat

HS

580

Dec

НА

NGC 3893

11 47.3

+48 51

11 .3

Sc. Distorted.

NGC 3949

х 2.з

4.5

Se.

- - - ---

with

а

Ьу аn

ЮС'j

а

V el'y conspicuous arm wi th patchy areas; the arm cu l'Yesmoothly to the Е and decreases а l i ttle in its' surface brightness until i t reaches i t turns Nl,'I';

а

faint knot suspect.ed

а оп

bright seetion is

оп

NGC 3898

Н.

оп

the S.p. side.

(8~) Contains а bright nueleus with а bright

eondensation elosely f; the р end is mueh more

-584

NGC 3953

11 51.2

+52 37

10.14

9.4

х

6.5

UNa

SBb:SB(r)be. UМa

+56 14

- -- - - - - - -

UМa

bulky and rounded than the f end.

the S.p. edge.

11 .4 2.7 х 0.7 Sa. Member of NGC 3846 - 389В group. 11 47.9

1.6

faint eompanion lies 4.4 to the

А

apparent

the edge

(8) Slight mottling; star оп the S.p. edge.

581

х

edge of the lens while а definite dark area is

knot whel'e

(1 6~) Oval wi th brightness variations in the oute: а

2.9

х333 eonsiderable mottling is visible around the

of the glow N of the nucleus, which is faint.

regions;

,

appear S to Ье tilted with а stellar nueleus; а bright surrounding lens has extended arms, and

oVal

sharp edge; winding from the W is

11. О

(16~) Large, bright and extended N.p., S.f.; it

(36) А fine one-armed spiral; а round, fairly . small central bulge is surrounded

+48 08

11 51.1

Соn

А])

m

Dec

НА

Cat

А])

m

(з6)

Bright, very large and mueh extended; the а

strueture is very subtle, eonsisting of

small,

round nuelear region immersed in an extensive (1б-~) Bright and some\'lhat elongated N.p.; S.f.;

it brightens eonsiderably in the middle to

а

weak bar erosses the eentre from

Arp Иkn

being

faint are winds S from the W end of the bar and

--------------------------:-----31 224 430

Н,

more conspieuous

outer area faint and diffuse.

vv

to

lens; an are of faint stars lies elose N.f. LP; the eentre is bright and elongated and the

NGC 3921

Е

very

small nueleus surrounded Ьу а fairly wide, diffuse

(В) Quite bright but small although detectable at

5В2

а

glow of non-uniform surfaee brightness;

U}1э. \v edge Рее. А loop of nebulosity extends from the Е edge• eurves to the S and makes eontaet wi th the ~ ~ •

11 49.5

+55 15

--------(14) Sho\'lS

13.4

-

- - -

2 • 2 х 1. 3

- ---

1 .

а stellar eentre in а faint Ьа о,

other detail evident.

оп

the W half;

an extremely

quickly fades; signs of spiral strueture are

оп

the SW side, specifically two weak arms, the brighter ending with

а

diffuse knot; both arms оп

are most apparent near the edge of the disk; the NE side there is very little structure. (16~) А

small nueleus is contained within

а

lens

whieh extends into arms; the eentre is extensive по

and

х176 а

about!

dark pateh lies in the S extension

the distanee from the eentre.

(ВУ Outer edges irregular and diffuse,

the eentre

somewhat brighter; а sшаll, faint star seems to Ье оп

the

Е

edge.

116

117

ws 585

Cat

Dec

НА

NGC 396з

11 52.4

+58 46

НА

Cat

т

12.7

NGC 4027

Dec

11 58.3

AD

m

-19 07

2.0

11.6

Соп

Crv

1.5

х

I

SBb.

VV Arp

(16~) Appears irregu1ar1y round with а bright " centre; а

and

а

bright knot in visible in the N оп

faint star

the S.p. edge.

66 22

SB. Dwarf companion l'iGC 4027

NGC 3982

11 53.9

+55 24

ап

quite round with in

а

exceeding1y bright centre

hazy surround, which

distinguishable from 587

NGC 3992

11 56.3

М

SBc. SN: 1956 -

109

+53 51

а

оп

LP makes i t hardly

star. 9.92

9.6 х 6.5

UМa

12~3.

S.p.; х422 there is а dark area near the

core, especia11y near the S side; а bright patch lies close to the tip of the S extension .

. fol'll

(1 о) Ova1 wi th а smal1, brigh t nuc1eus ln --------------------------::6588 NGC 4026 11 56.9 +51 14 10.7 3.0 х о.

(16~)

second arm curves round the

and connects to the W

епа;

по

the

distinct knots were seen.

а

-590

NGC 4038 4039 уу

245

Arp

244

1159.3 S

оп

faint star lies

рее.

-18 35

the f edge. 2.5

11.0

PKS 1159-18. 2 objects in

а

х

2.5

Crv

соттоп

uмa

,

enve10pe

with2 tai1s. (30) А pecu1iar object of high surface brightness; e10ngated with is

а

а

р

hole in the

side;

Е

апа

of the ho1e

1uminous patch and at severa1 points around а

the hole are NGC 4039 is

а

number of stars or stellar objects; broad wisp emerging S from and

curving around NGC 4038; the wisp has

Unl

----

nebu1osity; 13 mag star near the N edge.

SBa. DDO 102, 1з~6, 1ies 9

extends N from the W

NGC 4038, the brighter component, is broad

Very bright, large and great1y e10ngated N. f. ,

апа

(16~) Irregu1ar in shape with а bright centre;

- - - - - -.

(8) Small, very bright and stands ИР well; seems

- - - -

is smal1 and of fair1y high surface bright-

ness;

S.

Е

bar from the bar

586

а

end of the bar;

(8-~) А diffuse, 10\"1 surface brightness object.

1i-es 3.7 S.

(30) А pretty ring-tai1 system; опе of the arms is quite conspicuous,

• Р. P
А

- - - -

а

knot and

two ste11ar objects along its length; at the point where the two parts meet is

а

faint knot.

(16~) Appears as two irregu1arly-shaped nebu1ae

attached at their f ends; the northernmost appears

\.fSW.

.

•

Elongated a1most оп the meridlan,

а т

verY

'с Ь

..Фl

brighter and has

а

star just off the N.p. edge.

(10) Shows as an irregu1ar looking object of еуеп

small nuc1eus is surrounded Ьу а 1ens [то at e xtensions e 6 project very long arms; х17 the

with

pointed at the ends.

6-inch it 100ks simi1ar on1y sma1ler and fainter;

(8) Quite bright with ste1lar nucl eus ;

averted vision helps

with pretty faint outer portions.

texture and а

по

bright core; looks 1ike

а

shrimp

tail bent over the main portion; with

оп

the tai1.

а

119

118

Cat 591

Dec

НА

NGC 4041

12 00.9

+62 17

COn

(NGC 4088 continued).

(16~) Bright, round, with а bright central ~

(16!) Extended N.f., S.p. with the N extension

х176,

!'1kn

79

but по further detail noted.

12 02.9

10.20

+44 41

8.0

cO r

ееn

at

е

around the centre. х

----.

5.8 UJ1a SBc. PKS 1208+39. C1ass 1 Seyfert. ТЬе nucl eus т has varied Ьу 0.25 in 28d. Probably а тетЬе r or the СУп 11 cloud.

(8) Brighter towards the centre and showing sma11

NGC 4100

594

12 04.9

+49 44

Sc. Contains

а

irregu1ar in brightness. 4.0

11.9

х

1.0

UMa

weak, outer ring.

(16!) Shows а pronounced ste11ar nucleus in lщ

(10) An easy object; elliptical in shape, it shows

surrounding nebu10si ty; х176 dark areas seen to

а

-

curves towards

а

star which

р

NGC 4111

595

N.p. and S.f.; the former arm is brighter, and

а

СУп

11 c1oud.

- - - - --

6.3 х 1.8

10.91

а

member of the

СУп

Ьу а

Ю1а

dark 1ane.

11 c1oud.

NGC 4138

12 08.3

+43 50

11

.9

суп

Sa. (14) Extended N.p., S.f.; shows а mottled surface

(30) А conspicuous, very bright and cons ; . detacbe<1arge spira1 wi th patchy arms appearlng о о аr iП 15 1ve in p1aces; the brighter, more extens о,' reg1" nuc1ear о,: the Е side, winding S from а sma11 pOlturning I and then turning slightly Е; at the bO ut 1 ' i t weakens considerably, brightens for а te llS brigb ...а and then fades again; thereafter it 1 00У tb at again into а detached island featur e Ot (

an а sb

596

~

1о derab11

cometary; the second arm is fainter

+43 21

(18) Sma11, very elongated with а bright, star-like т middle; SAO 044039, 8.0, 1ies about 5 ' N.f.

incident. А 1arge chunk of the high surface . pro bat: brightness NW arm appears to Ье recedlng. member ofthe

12 04.5 Probably

we11-defined but not very bright nuc1eus.

6.5 х 2.8 UМa 10.58 +50 41 12 04.3 Sc. The optica1 and dynamic centres are not со­

а

fuzzy outer she1l and slight centra1 brightening.

SO. The nuc1eus is cut through

the nucleus.

(8!) E1liptica11y-shaped, even nebulosity ~o~!

18

х183

extensions;

..--

1ie around the nuc1eus and curved, spiral arcs

Arp

faint

being narrow and curved; dark mott1ing is visible

-

NGC 4088

а

star or knot.

- - - ..

593

Соп

and ends about due W of the nuc1eus with

surrounded Ьу fainter nebu1osity; we1l s

NGC 4051

AD

т

2.0 х 2.0 \J}. lа Sc. The centre shows very comp1ex structu~ _ _ _ 11. О

е,

592

Dec

НА

Cat

AD

т

---597

with

а

brighter bar of nebulosity across the major

axis.

-----------------------_ NGC 4144

12 08.8

+46 з6

12.4

5.3

х

0.7

Ш'Iа

Sc. (10) Elongated М.р., S.f.; shows а suggestion of

,\

mott1ing and dark regions.

120 WS

598

121 Cat

НА

NGC 4151

])ес

12 09.3

+39 33

Sb. SAB(rs)ab. Class 1

m

А])

11.6

1.6 Seyfert. Radio Х ,

and IR source. The nucleus brightened Ь between 1967 Jan and 1968 Nov. appears

оп

the end of

опе

Con

х

2.5

C~

12 13.9

Сота

SBa. Member of

х

2.3

СУП

1 cloud.

!JJ

(8) Fairly faint, small and round with

, 14 •o i1l

а

distinct

nucleus which is practically stellar.

I

- ---

12 14.0

(30) Considerably bright wi th very intere t'

Sb. In а

s lng structure; а very bright nucleus is surrou . nded \ а large, round dlffuse glow; this is si t t ' Ua ed ic ап extended, low surface brightness regio h' n w lch brightens into faint arcs at each end Опе Ь ' I l ' elng brighter; NGC 4156, about 5 or 6 NE, appears

6.6 х 1.6 Vir multiple system with NGC 4216, 4222 and +13 10

12.14

IC771. (16~)

Faint, although not difficult to see; it is

greatly elongated N.f., S.p. and appears fairly uniform in brightness with only

pretty faint and slightly extended wi th а con-

ening in the centre.

spicuous stellar nucleus.

(10)

(18) Appears as а Ыие star of about

2.3

11 • О

+13 10

Соп

~:t'a.y

У 0·5

NGC 4156

of the arms.

NGC 4203

А])

m

])ес

RA

ca t

а

slight bright-

А small, extended patch S of NGC

4216; it is

elongated in а N-S direction and of even brightness.

11 magwith

slightly fuzzy edges; ап extremely faint glow о!

по defini te dimensions surrounds this; а star vas seen in the posi tion of NGC 4156, anа тау Ьауе

599

NGC 4157

60'

NGC 4214

4228

12 14.4

+з6

28

9.85

10.6

х

10.6

Vir

Irr I:IABm. Spectrum shows Н« and [OII~ • The Н

surrounding

(8~) Quasi-stellar nucleus in а faint, o-val Ьаl0.

suggests possible tidal interaction. SN: 1954 9.8.

12 09.9

+50 38 11.9 5.9 Sa. SN: 1937 - 1б~2, 1964 - 16~O.

х

1 extends towards NGC

4190, and

Ьееп the nucleus of this object.

т

m

-

])])0 11 3, 15. 4 , li е s 1О

I

S\{ •

сот

1.0

(30) Bright, mottled anа fan-shaped with а wisp оп

- --

опе

end which ends in

а аоиЫе

knot; six very faint,

(8) Elongated N.f., S.p.; at LP i t appears t о Ье '$ of uniform brightness, but х152 the brightn esS )

very small knots line the major axis, including

а

(8~) Large anа bright; magnifies well but по

little uneven.

~

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Vir 600 NGC 4179 12 11.6 +01 27 11.6 2.2 х 0.9

Class uncertain, possibly an - - - - - - - - - -

(16~) апа

Е7.

Extended N.f., S.p. with

- - - - -

а

stellar n

needle-thin extensions.

(6) Stellar nucleus in small nebulo sity •

11

le us (;

Ье а

what appears to

detail is to

Ье

conspicuous nucleus.

Бееп.

~----------------------NGC 4216

12 14.6

+13 17

9.94

10.4 х 3.7

Vir

Sb.

(16"21)

~l jij onga t

е

developed. the

d N •f• , S •Р• ., the centre is wellр

side appears darker while the N

123

122 \oIS

Cat

Dec

НА

arm is mott1ed and contains

part being а 1itt1e р the visible centre; х160

а

brO19ht patch. (6) Shows а non-ste11ar nuc1eus disp1aced to

the

р

it comp1ete1y stretches across the fie1d of view, and at this power the centre is seen to

side of the major axis.

Ье

605

NGC 4217

12 14.6

+47 14

- - - anа

the 1'1 extension is

- - - NGC 4251

608

the

(8~) Brightish centre in extended nebu1osity.

NGC 42з6

12 15.5

Sc:SB(s)dm. An

(12)

9.82

anа of еуеn

weak, outer enve1ope. Member of

сl0иа.

------- ------х80 а

Сот

- - -- - ,

sma11, bright object 1ess than 1

in

8.38

+47 27

24.0

х

NGC 4258

12 17.7

М

Sb. Radio source. Pecu1iar nuc1eus.

106

9.6 Н

СУп

1 arms

cut a1most radia11y through the disk in opposite

texture, а bit 1ike а portion of the Zodiacal

directions, possibly

light.

--- --

nuc1eus. Member of

ness; there appears а slight increase in the centra1 luminosi ty, anа the overa11 appearan ce is uneven; 5 stars of 8 - 9 mag 1ie from the Е

12 16 • 3

+ :л 57

1О • 2О

18 • О х 2. 9

СУП

Sb. Radio source. Contains а very bright ,

srn з.1 1

nuc1eus or а superimposed st4r. ProbablY те

rn ber

аие

СУП

- - - - - -

(30) Extreme1y bright

to ejection from the

1 c1oud. anа very large;

the who1e

ga1axy appears 1ike а broad integra1 sign, with weak enhancements in arm features оп opposing sides; about

round to the NW side.

---------------------------------NGC 4244

1

0.8

brightness throughout; rather fine-grained in

(8~) Massive object of very low surface bright-

607

Сота

а

х

(6) Bright centre in sma11 nebu1osity.

is VII Zw 446. Possible member of М81 group.

(10) Large, very much e10ngated

long, which

and e1ongated.

26.0, х 8.7 Dra emission patch 5.5 SE of centre

+69 37

10

1.9

10.2

+28 19

12 16.9

Sa. Contains

brighter.

606

1

а good

seems brighter to the W; по real bright centre.

---

(16~) E10ngated N.f., S.p.; а slight central

brightening is visible,

wider than the extensions.

(8) Very bright streak,

11.9

Sb.

Con

AD

т

(NGC 4244 continued).

CO!l

(NGC 4216 continued).

Dec

НА

сэ,t

AD

т

4 or 5 patches are visible in the

brighter arm located оп the S side; the nuc1ear region appears slightly e10ngated anа is sharp1y cut-off оп the S side; as if affected Ьу dust; а ° conspicuous diffuse kno t 1 les

аЬ ои t

30" N of centre.

(16~) Shows а sma11, bright centra1 core anа

of the CVn 1 cloud. h о ch iS

(16~) An extreme1y long, narrow ray ~ ~

brighter towards а non-ste1lar centre,

thi S

wide extensions; the f edge of the 1'1 extension is bright, anа there is а bright streak оп the р

125

124

vlS

Cat

НА

Dee

Ca t

AD

т

СО!)

(NGC 4258 eontinued)

12 21.3 sB

edge of the S extension, whieh a1so d' lSP1ays dark patehes.

faint are of nebu10sity NW of the nue1eus.

NGC 4274

12 18.6

+29 45

8.7

х

3.5

Сот

HS nue1eus. Smooth, outer arrns form

а

(10) Oblique with

а

pronouneed ste1lar nueleus

and varying degrees of brightness.

(6) Fairly bright nueleus in oval nebulosity; РА

( 8) The nue1ear area i s то tt1 е, d and а dark area, para11e1 to the minor axis, is N of cent re,

610

1. О

х

---- ----------

lOt

а

рее.

2.2

10,8

+30 02

Соп

AD

т

pseudo outer ring.

( 8-21) The nue1eus appears irregu1ar in БЬаРе , possibly rather triangu1ar at нр·, the extens'

to the N is brighter with

Dee

НА

----614

NGC 4319

140

о

о

- 320 ;

а

9 mag star is 15

12 20.6

+75 45 13.0 3.1 SBb. The QSO Mkn 205 lies 42 " S.

х

I

N.f.

2.5

Dra

сот

outer arms form an outer ring. JV:ember of the

(16t) Oval nebulosity with а brighter, поп­ stellar eentre; Mkn 205 shows 80S а faint stellar

Сота

objeet elose to the S.p. edge of 4319.

SBa. The bar is seen a1most end-on whi1e the

1 c1oud.

- - - -.

(10) E10ngated a1most E-W; the nue1ear area is oval and part of the region

р

615

NGC 4346

this defini tely

12 22.2

1.6

11 .6

+47 08

х

0.8

СУП

SBa.

appears brighter; the ou ter regions are diffuse

(10) Very small, fairly bright pateh of light

with ill-defined borders.

with

(6) Diffuse nueleus in ova1 nebu1osity. 611

NGC 4278

+29 26 1о. 43 6 • 3 х 6. 1 сот Е. PKS 1217+29. Contains тanу globular elus ters • 12 18 • 9

Member of the

Сота

616

NGC 4290

12 19.6

+58 14

12.7

SBb. SB(rs)ab.

------------

- -

1.5

х

- - - -

(10) А small nebu10us pateh of еуеп

0.7 Ss bt e , brig Р

11.4 12.0 х 10.0 СУП I NGC 4399, 4400 and 4401 are part

+33 41

of it. Probably member of the

- -- -.

1 eloud.

12 24.5

definite shape; eentre slight1y brighter.

Se:SA(s)n рее.

--617

612

NGC 4395

по

(16~) А faint object,

СУП

1 cloud.

being only slightly аЬоуе

the sky brightness; х160 а brighter eentre seen. NGC 4414

12 25.2

+31 22

9.7

3.0

х

1.5

Сот

Sc. Contains а diffuse nucleus. SN: 1974 - 13~0. Member of the (2~)

Сота

1 cloud.

Quite bright with

а

very bright centre and

two suspected bright areas N.f. and S.p. eentre.

127

126

ws 618

Cat NGC 4419

RA

Dec

12 25.7

m

+15 11

Sa/Sc. AN nucleus. smooth arms appear

- - - -РА 1200 -

AJ)

11.4

2.3

х

0.7

619

NGC 4448

12 27.0

+28 46

Sb.

- - - - -

-

- -

high resolution аие N of centre, where several

- - - - -- - -

П.4

-

(8~) Faint ob,ject with

- по

3.0

х

stellar points are visible; these could Ье иn­

1.0

а

resolved ОВ associations, or very bright stars. (18) Elongated in РА 450; structurally, it has

---

а twinkling,

сот

starlike nucleus surrounded Ьу а

fainter, diffuse centre with two other quite

- - - - sign of

AD

knot; the most interesting region is оnе of

strong, dark lane and оп photographs.

3000; oval in shape with brighter centre. (8)

т

(NGC 4449 continued).

Co rn

А

Dec

RA

Ca. t

Con.

Соn

bright regions each side, all being surrounded Ьу а large,

а

defini te nucleus but slight central brightening.

faint glow; а dark 'nick' was эееn

S.f. the nucleus. (12~) Irregularly-shaped rectangle with а

620

3С

273

12 26.6

+02 19

12.5-13.0

Vir

conspicuous nucleus; two very faint knots are

QSO. Low redshift object consisting of two optical components, an almost stellar

visible, the brightest close SW of the nucleus.

оnе

(8~) Rectangular in shape with the NE еnа of

" diam and an optical jet. Separation about 0.5

the minor axis being possibly

" 19.5. Radio source.

there appear to

Ье

а

little wider;

some brighter regions

оп

the SE section of the major axis.

(10) 1ndistinguishaыe from а star and visible

(8) Brighter centre but not stellar; not quite

with direct vision.

spindle-shaped but blunter; the N еnа эеетэ to 621

NGC 4449

12 27.0

+44 14

9.68

10.1 х 8.7

сУn

Ье

Irr 1. Radio source. Contains 81 known Н II regions. Member of the (36)

А

СУn

spectacular object;

1 cloud.

по si~

--of

(2i) Bright nucleus which 1s not round; the S.p.

- -.

spir~

'good

structure and thus obviously irregular; ln ·nt seeing it appears resolved into тапу fal a1. 1 forJII knots, some appearing stellar; the over Sll is rectangular; а faint wisp juts off the t е; f сеn r еnа and а weak dark patch lies аие Е о tlgt!', . ts lе а knotty, weak enhancement runs along 1 diffU" und ro including the nucleus and а bright,

brighter.

еnа

is rather rounded and rays seem to extend

N.f. the centre; the periphery is mottled.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~_ 622

NGC 4450

12 27.3

+17 14

Sb. Contains

1 0.11

а рэеиао

8.8 х 6.0

Сот

outer ring.

(8~) РА 300 - 2100; shows аn intense stellar nucleus which lies slightly N of the central

,

bright area;

а

9 mag star lies 4

to the SW.

128 129 \-18

623

Cat

НА

NGC 4485 уу

30

Dec

12 29.3

+41 51 1rr. Distorted.

- - - -

-

т

Cat

AD

12.02

3.3

х

cOt\

3.1

NGC 4494

C1{t\

. , Wl th а rect ' box-shape; а very small faint knot. aJl€'1l ~ , ls clo se (16) Close N.f. NGC 4490' bright el S~, , ,ongated right angles to blGC 4490 wi th а much bri h а g ter middle. (8) Pretty faint and small and

'th el er round

elongated; brighter centre. NGC 4490

vv Arp

30 269

12 29.4

12 29.8

AD

т

+26 03

10.7

1.2

Соn

х

1.0

Сот

Е1 /2.

(12) Moderately bright nucleus in outer

+41 47

9.81

8.9 х 4.7

01'

---

,

nebulosity; about 2.5 in diameter.

(2i) Appears round with

-626

Ье

NGC 4527

--------

the Е half; the NW end is curved towards NGC in the сеn tre а small, tvlO-аrmеd spiral

А

elongation it

тау

N.f., S.p. direction. +02 48

star

тау Ье

10.51

7.5

superimposed

х

3.5

оп

Vir

the nucleus. т

Contains complex dark lanes. SN:1917, 15.5.

,

,

(12) 2.0 х 1.5; slightly irregular with по nucleus.

- - - - - -.

weakly enhanced along the Ы side, especially оп

а

12 32.9 Sb.

CVn

(36) Shaped like а broad integral sign and is

in

а much brighter

anу

nucleus; if there is

Sc. 3С 272. Distorted. Both thi s and KGC 4485 are probable members of the СУn 11 cloud.

4485;

Dec

- - - - -

(36) Very bright and extended

624

НА

627

NGC 4565

12 35.1

+26 08

9.56

Sb. Radio source. Member of

20.0 х з.6 Сота

Сот

1 cloud.

(30) Closely resembles its photographic

pattern is suspected, apparently winding from а

appearance; the planar dust lane is clearly

diffuse, non-circular central region; there is

visible, splitting the central bulge into

по nucleus wi thin thi s area;

two unequal hemispheres of light; the nucleus

the two arms are

very short and fade rapidly into the surrounding

is conspicuous

nebulosi ty; the S-shape of the galaxy appears по'

the latter being most obvious in the bulge.

to Ье related to this spiral structure; а faint, detached nebular streak lies оп the N side. (16) Very bright, large and much brighter to the middle where there is аn intense core; the surrounding diffuse halo has а relativelY straight edge оп the f side; some mottling. (8) Very bright elongated centre in the ou ter nebulosity; much larger with averted vis ion •

оп

оnе

side of the dust lane,

(16~) А stellar nucleus in аn oval lens

which develops into long extensions; the dark lane is visible through the centre and х346 а

shows (8~)

А

light streak N of the lane at centre. bright line is seen across the centre

plus traces of the absorption lane. (6) IJarge, diffuse nucleus; the extensions are fine lines;

по

absorption seen.

130 131

WS

628

Cat

RA

NGC 4605

12 38.9 Se а

])ее

+61 45

А])

т

9.6

3.0 х 1.0

рее. Patehes of dark material

1J}!a

are pre8el1t .

!~

eomplex nuelear region.

NGC 4625

12 40.5

IC

- - - -

3765

---

а

- _.-

3.5

12.45

+41 33

Se. Probably

А])

т

-

-

- - -

-

-

-

2.5

х

СУп

member of the -

Соп

i 8 to Ъ е seen, the eentre being extended; the th S edg e Of е major axis appears to Ье еОПуех th . ' е S ed be1ng mueh straighter; the f exten~' ge .,1.0П na:r:rows more th ап the р опе; х176 dark mott1" . 1ng 18 seen a10ng the entire major axis being . ' ve:ry eVident 1.П the р part; х351 the dark patehes res Ь ет 1e those in М82 while а bright streak 1.·s оп the

СУп

11 eloud. -

-

(10) Shows an indefinite shape and

(16~) Elongated N.p., S.f.; по nueleU8

- - - - - -

по

bright

core; easily visible with direet vision. (8~) А

small, misty round spot whieh gradual1y

brightens towards the eentre; at HP the nuclear region is a1most lost; very faint overal1. NGC 4627

12 40.8

+32 43

12.53

3.7

х

СУп

3.4

Е. The outer parts are distorted Ьу NGC 4631.

f extension.

(30) Bright, sma1l, diffuse; el1iptiea1 in shape

( 8-21) J3right with some mottling evident· th . , е тlnor axis appears of еуеп width for most of i ts length.

with

NGC 4618

12 40.3

vv

73

Sc.

Arp

23

+41 18

10.83

6.0 х 5.6

6'2

CVn

А

II c1oud.

nucleus. circular; х160 brighter in the

centre with diffuse edges;

very massive spiral arm emerges from the curves S and then Nvl. Probably а member of the СУп

по

(16~) Faint,

(6) Extended with eondensations. 629

])ее

RA

cat

Е,

- - - --

NGC 4631 ир

281

12 40.9

+32 41

9.29

х333

19.0

slight1y extended. х

СУп

4.4

SB/1B/Sc. PKS 1239+32. Shows strong absorption at the centre. Connected to NGC 4656 Ьу an Н 1 bridge. (30) Very majestic; it is littered with knots,

(30) А one-armed barred spira1, the bar being

patches and mottlings all along its length, and is

bright and very diffuse; off the Е end of the Ьа!

very diffuse in its light distribution;

а conspicuous diffuse arm emerges to the W aдd

а

nucleus, but

оп

the SE side is

ап

по

sign of

arm-like

winds W; three knots are suspected in the arm,

feature that ends in

on1y опе being definite; the overall character

jut out of the plane of the galaxy;

of this object is опе of low surface brightnes s , R ( 8-21) loundish image wi th по central brightenin g',

probably about 14 mag; signs of dust near centre.

х102 the S edge appears а little brighter.

bright, non-stellar knot

а

faint knot and appears to опе

knot is

(16~) Bright centre in bright nebulosity; х222 а р

the nucleus.

(8~) Mottled inner regions with а condensation р

the centre; the W end is thinner and the angled in РА 400 - 2200.

Е

end

132 133

\{S 6зз

Cat

НА

NGC 4651 уу

56

Arp

189

Пес

12 42.5

+16 32

т

АП

cat

СО!)

6.1 х 4.5 Sc. Radio source in the tail is apparentl СОт т у not connected. The 19.0 QSO 3С 275.1 lies ' ------------___ 1 S 10.78

--а ver

-

(1 о) Fairly large and brig'ht wi th

.

NGC 4666

4657

12 42.7

+32 19

14 • 5 х 4.1 ----CVn SB(s)m. Possible member of the СУп 11 cloUd.

---

6}7

NGC 4670 Arp 163 Haro

9

,

Vir

1.4

по

SO?

0.8

12.7

+27 16

х

0.5

sign

Сот

Two stubby extensions emerge from the main

body, both curving slightly at the ends.

NGC 4676

12 44.9

+30 52

8ВО рее.

р

side brighter.

centre brighter.

14.1

1.9

х

0.8

Сот

"The f'iice". Tidal effects are in

1e

819

80 +

1C

820

evidence, with

vv

224

fainter, curved

Arp

242

а

straight tail to the N and опе

а

to the 8.

(107) А strange pair, the brighter component is

(16) 8hows а conspicuous bright patch in the

like

middle of 4656 and another where i t merges into

head is quite diffuse and shows

4657; the wholeobject has а grainy texture.

the tail is straight and long; the second

а

mouse or tadpole with

а

long tail; the по

nucleus while сот­

(8) Ап object which needs good conditions, where

ponent is smaller and slightly extended and shows

it appears as а thin streak with а slightly

weak enllancements, including

brighter centre.

-------------------------------635 NGC 4665 12 43.9

4664

12 44.0

(8~) At ИР а faint glow;

being attached; the galaxy then extends аБ а Ьгом

Е and ends at the 3rd of the knots.

х

14~0 •

elongated, diffuse nebulosity;

ended wi th а t' par 1. s а di ffuse, slightly extended glow оп the S\'l end, а star also

knots; at this point the light distribution curves

4.5

(16~) Stellar nucleus surrounded Ьу slightly

ех

length until i t reaches the first of 3 conspicuous

12.0

of the companion NGC 4668.

- - - - - - - - -h t

diffuse glow to the NE which fades along its

-00 19

Соп

the extensions are of quite large size;

10.50

(30) Very bright, larg е an d тис twist at опе end', the brl'ghtest

12 43.9

АП

т

(10) А tiny stellar nucleus in an edge-on spiral;

.

brlghter centre wi th а stellar nucleus' ,l~ . , ' а 11. ttl e extended wlth lll-defined edges; х148 it appea:rs slightly mottled. NGC 4656

Пес

Sc. SN: 1965 -

у Sl1.ght

,

634

НА

+03 12

11 • 1

1.2

х

0.8

Vir

8ВО. 8hows traces of smooth arms leading into а

pseudo outer ring.

------ -------

а

stellar nucleus.

(16~) х84 not bright but is elongated N.p., 8.f.; х176

it consists of two parts, the 8

опе

being

small, bright and almost stellar; N of this is dark area followed

Ьу

an elongated, thin wedge

of nebulosity to the N; the 8 end is apparently

(12) l' in diameter, quite bright and slight1Y

the nucleus and there is little nebulosity 8 of

irregular.

it;

х422

the dark area is quite prominent and

а

134 WS

135

Cat

НА

l)ec

A:D

т

NGC 4710

12 48.3

+15 18

12.0

3 5

•

о

Х.5

(б)

~ Сот

Sa. Nucleus partly hidden Ьу а dark lane.

- -- -

~

- - -- - - --- - -- --

~GC 47 б2 642

:Diffuse, with

ution; а broad, diffuse nuc1ear bu1ge is f1

nucleus;

оп either side of the bu1ge are pointed and а

1itt1e patchy; по nuc1eus seen.

(8~)

-

NGC 4775

12.1 х 10.0

pseudo outer ring. 3N: 1940 Mernber of the

Сота

Vir

х222

the N extension is rnottled with

Non-stellar centre in uniforrn nebulosity. -об

12 52.4

оп

644

NGC 4793

12~8, 19б9 - 15~O.

11. б

29

У.7 х

Vir

1.7

brighter centre seen plus

12 53.4

+29 05

РК3

1252+29.

outer arrns,

------

а

bright spot

the N edge; the 3 edge is poorly defined.

3с.

1 c1oud.

оnе

1.6 х 0.7

11.8 5С4.022.

Сот

Contains 3 weak

extending to

а

dwarf satellite.

(30) х300 i t is very bright and 1arge; а long

(16!) Elongated N.f., 3.р.; the centre is seen

bar with bright concentration with two curved

to

sections at the ends forrning parts of the ring

brighter than the 3.

which is very weak away frorn the ends of the

(8!) Quite bright object with а brighter area

bar; the appearance is that of а ship' s ancho r ; аn extrerne1y faint knot is visible, apparentlY

in

оnе

of the arrns, which were not seen.

(18) 3rna11 and bright with occasional thre e lobed appearance; а star lies just N of the srnall, bright nucleus.

а

(16!) Irregularly round, like а puffy cloud;

Сот

3ВЬ: 3AB(r)b. Оnе arm forrns an incornp1ete,

0.4

Long extensions are seen with an elongated

х349 а

9.4б

х

3.

rnajor axis; bright knots f1ank these.

+25 41

3.7

11.0

tip, the 3 extension is of uniform brightness.

еасЬ side of the centre perpendicu1ar to the

12 49.2

small, bright nucleus.

dark area halfway between the nucleus and the

(1б) E10ngated 3.р., N.f.; dark areas 1ie оп

NGC 4725

Соn

3а.

(1б!)

anked оп opposite sides Ьу dips in the brightne . ss, the weaker 1ight intensity in these regions su ggests the presence of dust; the brightest extensions

а

+11 22

12 51.7

(3 б ) А beautiful ray with uneven light d'

1. stri b~

б41

A:D

т

(NGC 4725 continued).

the N extension narrbws as it recedes. б40

:Dec

НА

Cat

Co n

(NGC 467б continued).

---645

Ье

brighter and the N extension wider and

in the

НЕ

end; 8 mag star close to the

Н.

----------------------NGC 4826

12 55.5

м

3Ь. РК3 1254+21. "Black-eye" galaxy. Possibly

64

+21 49

6.6

8.0

х

5.0

Сот

mernber of the CVn 1 cloud. (60) Oval nebulosity extended Н.р., 3.f.; the

а

137 136 \0/8

Cat

Dee

НА

СаП

(NGC 4826 eontined).

NGC 4900

-

slightly eurved; the nueleus is conspieuous оп

iness

(16)

пеаХ'

the lane

оп

the

Е

266

Nkn

59

-

649

NGC 5005

Sb/Se.

а clear

+37 11 9.89 8.1 х 4.7 СУП PKS 1308+37. Contains several knotty

arms with dark lanes.

- - - - - - - -

(16~) Bright and elongated with an extended

absorption is not distinguished with eertainty.

nueleus; х333 the f extension is brighter.

(10) Oblique with bright core and stellar nueleus.

СУП 12 57.9 2.0 х 1.0 12.7 +35 00 Irr + Е? The brightest eomponent is at the S

end. Mottled, fainter material extends (з6) Pretty faint,

-

- - - - - - --

conspieuous; it possesses а bright knot оп the S епа whieh is barely distinguishable from а

---

star; the remainder is а diffuse, elongated glO" whieh is patehy and brightest at the eentre.

12 56.8

1.6

+37 34

SA.

х

1.5

СУП

---

(16) Round with slightly brighter middle; а faint star lies

оп

the edge.

middle with а slightly non-stellar nucleus.

650

large, extended and diffuse;

-----------------------

(8) Hather faint and diffuse; quite bright in th~

Н.

the low surfaee brightness does not make i t very

NGC 4868

13 09.8

stellar and the whole objeet glows strongly; the

------ - - - -

647

- - - - -- - --

- - - - - - -

eentre anа а pretty bright star оп опе end. hed at 400. (6) Faint with по nueleus; star attae

outline; the nuelear region is small but not

Arp

Vir

extremely weak bar; а bright nueleus is at the

А mueh brighter middle ends in а stellar

powers.

NGC 4861

1.7

suspeeted пеаХ' the edge; also suspected is an

this side is Suspected.

nucleus; the absorption is very evident at all

646

х

ring-l ike enhancement, broken in опе plaee, is

and

side; Some patch_

(8) Very bright and eonspieuous with

1.7

interior; the edges are fairly эhаrр, and а

a.tl.d

edge of the dust lane, the

latter being darkest

---

11.3

(з6) Like а planetary nebula, appearing as а

-eYe~

is not totally dark and appears fairly braad оп опе

рее.

+02 38

symmetrie, oval glow with dark spaees in the

(30) Very bright, large and 'oval; the "black

lies exactly

12 59.5 S

dark absorption pateh at the eentre appears t o make the nueleus offset to the W.

m

Dee

НА

ca t

AD

m

Соп

AD

NGC 5033

13 12.3

+з6 44

10.18

12.3 х 5.8

СУП

Se. PKS 1311+з6. 2 arms wind in opposite directions. Contains а large superassoeiation. SN: 1950 - 18~2.

- - - - - - - - (з6) Bright, very large and extended; the соп­

centration at the centre is off-set апа the W side of this region gives а strong suspieion of being cut-off Ьу dust; а dust lane or knot is suspected just S of the nuclear region; spiral structure appears in two places, both being

138

139

WS

Cat

Dec

НА

m

AD

Cat

very faint and eompletely diseonneeted from the eentral seetion; оnе of the spiral features

651

NGC 5194

13 28.9

+47 19

5195

13 29.0

+47 24

J>1

vv Arp

51 1

AD

Соn

8.35

14.2 х 9.5

СУn

9.49

8.9 х 7.4

m

Бе + Irr. 4С47.з6.1. NGC 5195 appears to Ье devoid of Н 1. БN:(NGС 5195) 1945 - 14~0.

85

envelope elongated E-W.

(30) The spiral pattern is elear and bright

(8) 100ks almost round at first sight but Soon

with almost а three-dimensional effeet; nearly

shows as being elongated; faint outer regio!)s.

two dozen knots and enhaneements are visible

10.0 х 5.0

СУn

-

13 14.7

м

БЬ. БN: 1971 - 11~5. Member of the М101 group.

+42 10

10.1

- --

nueleus surrounded

Ьу а

nebulous glow whieh

solid-looking nueleus; it stands еan Ье

NGC 5128

13 23.8

Arp

Е

рее.

Radio souree.

--

~W

well but

по

seen; an8 mag star is close NW.

-42 53

------

6.98

brightening considerably near the connection point; NGC 5195 is shaped something like an earlobe with а strong dust patch SW of its nucleus and а sharp Е edge; the, combination appear spiral.

(8) А rather pale, glowing oval with а brighter detail

and the eonnecting arm is easily visible,

of the linking arm and the absorption make it

fades off at the edges.

153

6~'

(10) Small, eompaet bright eentre in аn outer

(16t) Very bright and large with а small, bright

652

Dee

ineludes an extremely faint knot.

NGC 5055 6з

RA

СО!)

(NGC 5033 eontinued) •

31.0

х

25.0

----

Сеп

- ---

(16t) А magnificent sight, being obviously spiral; two аrшs are seen, оnе ешеrging from the nuclear component of NGC 5194 in а S.f. direction and then turning Ы, it then runs аlшоst s~~aight for а while, where tiny points

of light are intermittently seen, then turns

(16t) Very large and pretty bright; а eireular

W and ends near the р part of the galaxy; the

shaped glow of nebulosity with the Б half being

other аrш is more unifоrш in brightness and

brighter; а wide, dark division crosses the

winds through 1800 to fade into the sky f the

centre, а star being in the Ы.р. end of the

galaxy; NGC 5195 is bright and looks like

dark division while another is seen in the N

half а disk; it is brighter оп the straight

part of the

Б

edge and has а stellar nucleus.

half.

e (12t) А lovely divided nebula; the dark lan f ligbt seemed triangular in shape and а spike о

with а bright, well-defined nucleus; outside

shows in the Б part of the dark regionj

this is а large, faint glow with а section-of

faint halo surrounds the objeet.

а "еТУ

(10) The larger object is very slightly oval

а spiral аrш in the S.f. section; irregularities

in the structure are also suspected; NGC 5195

141

140 Cat

Dec

НА

m

cat

AD

NGC 5 2 3 б 83 М

(NGC 5194-5 continued). appears irregu1ar with faint outer areas. (8) Appears as two glowing patches a1most а

is visible

faint trace of the connecting оп

Е

the сan

brighter knots

Ье

made

ои t

NGC 5198

13 29.2

+4б 48

315

Arp

288

7.0

Нуа

source. AN nucleus. Over incipient bar 1ies in the

14~0, 1950

m

14.5, 1957 -

very condensed core which is not quite stellar;

; does

0.7

х О.б

СУn

-

inite1y brighter

extensions going NW and SE

from the nuc1eus and invo1ved in the larger, diffuse outer envelope; definite mottling is

(1б~) Brighter centre in circular nebu1osity;

seen throughout the envelope and with averted

three stars lie close to the N.

vision the tips of the bright extensions are

(10) Very faint and almost atellar at LP; at

curved slightly and quite short; two faint

а

13 33.7

stars are at the tip of each arm.

small nucleus is seen, and it

appears slightly oval in РА 800.

уу

н 11 r~gions. Ап

х

(10) Large and bright with а much brighter,

- ----

higher powers

NGC 5221

1Н

sc. PKS 1334-29.

8.0

i t appears slightly elliptical with two def-

Е.

655

10.1

Соп

- ------ --------- -- ----

а:гщ

not stand magnification well. б54

-29 37

AD

m m 15.0, 19 б 8 - 11.9.

side and some of the at times

m

centre. SN: 1923 -

contact, both with very sma11, star-1ike centres;

13 34.2 79

in

Dec

НА

+13 57

2.0

14.5

657 х

Vir

0.7

Sb. Plumes of materia1 extend NW and SE.

----------

,

- ,- - - - - - -

NGC 5248

13 3б.2

+09 01

11.3

3.2 х 1.4

Воо

Sc:SAB(rs)bc. Peculiar nuc1eus. (30) Two arms are clear1y visible as distinct

(1б) Elongated oval about 1. О х 0.5; of 10\\'

enhancements immersed within an elongated,

500.

diffuse glow; neither arm appears directly

surface brightness but easy to see;

РА

connected to the central bu1ge although they б5б

NGC 5222

vv

315

Arp

288

13 33.7

+13 52

Е. NGC 522б is а

contact to the

Е.

---------

14.0

1.б х

1.2

Vir

disrupted spiral almos t in

-------

---

hter (1б) Quite bright and suddenly much brig

e to the midd1e; round and about 1:0 in siz ;

. gnS

NGC 522б is very small and round with по S~ of central brightening.

curve towards it; the bulge appears diffuse and contains

по

diffuse knot near the end of the (1б~) Bright,

а

nuc1eus; there is Е

bright, arm.

ste1lar centre in ап outer

enve10pe extended N.p., S.f.; х1бо the area N of the nuc1eus is brighter and near the edge of the N extension;

а

knot 1ies х333 а

patch 1ies S of the nucleus. (б) Faint,

diffuse centre with stellar point.

142 у/8

658

143 Cat

RA

Dec

HGC 5273

1341.0

+35 46

80.

- - - -

AD

т

12.7

2.7

2.3

х

NGC 5457 101 м

CVn

- - - - --

------

Dec

НА

Cat

Сап

14 01.4

+54 35

т

AD

Соп

9.6

10.0 х 8.0

Ш1а

Sc. HGC 5449, 5450, 5451, 5453, 5455, 5458, 5461 and 5462 are knots in the spiral arms.

(14) 8tellar centre wi th а small area offaint surrounding material; the edges are fuzzy.

еl'

-------------------------------.. 659

NGC 5297

13 45.3

+44 00

12.0

5.6 х 0.9

CVn

Бс.

total of

20 knots and enhancements are scattered within

р.

and outside the visible arms; some of these

(14) А thin spindle with а 9 mag star attached

are very bright; NGC 5447, 5451, 5455 and 5458

to the N edge; overall brightness with the Ьу а

а

sense out of the spiral pattern;

I

centre larger

complicated object to disentagle in the

places and it took careful study to make some

slightly brighter centre; NGC 5296, 15 mag, is faint, nebulous spot 5

а

together' and appear disconnected in тanу

- --

а

is

30-inch; the arms are difficult to piece

(16~) А faint ray elongated Н.р., 8.f. with а

seen as

(30) Extremely large but not very bright; it

appear faint, HGC 5453 is at the tip of fan-

small degree.

shaped luminosity extending S, NGC 5449 shows 660

NGC 5371

13 54.6

+40 35

11

.7

4.0

х

2.8

as

СУn

3ВЬ. 3B(rs)bc.

а

close, faint pair of knots. NGC 5462 is

the brightest knot and NGC 5450 shows three condensations and is mottled;

(36) Initially appears as а large, elongated diffuse glow but subtle features appear

near, but not connected to, the ends of а we~, cigar-shaped bar'; the 3 arm is more conspicuo us and includes two knots, опе large and diffusej between the 3 arm and tbe bar а faint arc whic h ends in а diffuse knot is suspected, and seems to Ье part of а closed ring encircling the ЬаТ. all these features are faint in the glow of the s

а

nebulous star at LP;

(10) Oval with

а

а

9 mag s t

ат

resernble

close [.

faint, stellar core.

wi~hin а

small, diffuse region.

careful inspection; two spiral arms wind from

(16~) Circular with а stellar nucleuS;

very small,

non-stellar core is at the centre

оп

underlying disk.

а

(16~) Very large and diffuse extends over

most of the field; а relatively bright central region, bright stellar nucleus and knots in spiral arms are visible, all with ease. (8) А faint, fairly large misty patch which is not quite circularj

а

very small, bright nucleus

shows in the nebulous glow; best conditions are needed to make the most of this object, but

попе

of the spiral features are visible. (6) Large featureless blur with possible signs of some condensations.

144 \VS

662

Cat

RA

Dec

blGC 5474

14 04.2

уу

Sc. Distorted. Member of the

344

145

m

10.91

+53 47

- - - --

AD

7.4 М101

------

САП

х 6.в

NGC 5533

NGC 5678

1JHa

group.

m

+58 01

11.2

AD

2.6

х

Соп

1.0

Dra

~

r

(36) The features are extremely subtle;

а faint

oUnd area in the Ы end; х349 а large, eurving d a:rk

stellar nucleus is surrounded

region separates the bright and faint part

diffuse region of moderate surface brightness;

(В) Faint and featureless; РА

1700.

14 15.1

2.0

+35 27

Sb.

12.9

,

14 31.3

Dec

SB. Distorted.

---

(16t) Irregular in shape with а bright

66з

RA

Cat

х 1.В

Б.

ап

-

РА

extremely faint short curve is suspeeted

faint knot;

1200; it

is brighter in the middle and about 1:5

broad,

just outside this region, plus an extremely

Боа

- - - - - - - - - - --

(16) Q,uite bright and elongated in

Ьу а

х 0:5.

оп

the opposite side of the galaxy

is

а

ап

extremely faint, barely reeognizable arm

very diffuse extension, thought to include

whieh nearly extends straight for some distance; the nucleus is off-eentre in the underlying glow.

(10) Faint, small slightly brighter eentre.

(16~) Shows а well-developed centre with

664

NGC 5600

14 22.6 S

1. О

+14 45

х

0.7

Боо

extensions N-S; NGC 5746

668

(8t)

х69 visible as а tiny but prominent spot;

х111

а

14 43.7

NGC 5665 Arp

49

14 31.2

+08 11

12.7

1. О

хО

.8

Воо

Vir

А long spindle with а sharp edge оп the Е

side; the nuclear bulge includes

а

faint nucleus,

S рее. The inner regions are distorted with а

so the galaxy is not exactly edge-on;

number of eondensations and dark areas.

is deteeted from the underside of the dust lane

- --

but а slightly brighter nuclear regio n •

------------------------------5 NGC 5676

10.6з

+01 55

Sb.

whieh eauses the sharp

(8t) х77 i t appears ra ther fain t and elongated re in РА 1200 - 3000; higher powers reveal по mo

666

stellar nueleus is seen.

very faint, stellar nueleus suspected.

(36) 665

х222 а

рее.

+49 34 11.2 3.0 х 1. Sc. Contains 4 superassociations. IC 1029, 14 31.9

ВоО

"ttle elong а l 1.

а diffuse halo surrounds а bright

intense eore.

--669

т1." ddle

ated ; ~

an d

light

edge.

а brighter middle and а

tapering S.f. end.

(6) Faint oval with

по nueleus.

~------------------------

NGC 5820 Arp

h m о' is at 14 30.7 +50 07 •

(16) Bright, quite large an d

(18) Elongated, with

Е

по

1з6

14 57.9

+53 59

12.8

0.7 х 0.3

Воо

E/SO. Faint material extends from the SE end.

(16t) Elongated E-W; there is а bright eentre with extensions, these being brighter at their respeetive ends.

146

147

Cat

\vS

670

NGC 5846

Dec

НА

15 05.2

+0142

10.5

1.0

Е.

х

-

(16) Ноипа anа quite bright with а stella:r

х422 а

'

(8)

СО!'е.

faint with а Ve:ry

anа

,

а

bright core.

(8) Rather faint at first but improves at hl' h g е!: power, which makes it look larger although

А

--т

NGC 5850

15 05.9 SB.

+01 38

~ember

12.9

2.6 х 2.1

of the NGC 5850 group.

than

а

по

NGC 5879

епа

NGC 5866

674

NGC 5907

15 09.1

+57 05

м

102

SO

11.5

6.5 х 3.0

the inner, central part

3.3

12.1

Sb. SN: 1954 -

14~9.

(16) Elongated

anа

х

1.3

Dra

slightly brighter towards

15 15.2

+56 24

10.41 15.7 х 2.0

possible member of the

small nuclear region wi th small nucleus.

+55 51

anа

Sc. NGC 5906 is part of it. SN: 1940 -

other detail other Е

middlej

Воо

- - --

(36) А classical lenticular galaxy with pointed endsj along the major axis is а conspicuo uS

М101

Dra

14~3.

group.

(16) Bright anа very elongated with а brighter

of the bar.

15 05.8

of the N arm.

(6) Small and faint with а brighter centre.

(12) An oval, featureless blur. 672

епа

the

the middlej quite bright.

- ---

an extremely faint star is attached near the

central areaj at

is very bright.

Vir

(з6) Considerably bright, large anа extendedj

the bar is evident, but

Соп

bright ellipse at LP; at HP the ends

more diffusej bright, non-stellar nucleus. 671

р

very faint star

appear more pointed

small, brighter centre. (12) Oval nebulosity with

AD anа

halfway between the tip

compact dwa:rr. _ _NGC _ _ 5846А _ _ _ is_ а _ high-density, _ _ _ _ _

the companion is small

m

(NGC 5866 continued).

1.0

- --

Dec

НА

Cat

AD

m

675

NGC 5929

по

15 25.2

sign of the absorption lane. +41 46

5930 Arp

90

1 Zw 12

E/SO + Sa.

А

14.0

1 .1

х

1. О

13.0

2.2

х

0.9

CrB

curved plume appears to link both

objects. Extensive outer nebulosity.

-------

- - -- -

- - - - -

dust lane, remarkable for its extreme narro w-

(16) NGC 5930 is bright anа much brighter in

nessj this is only visible across the bright , . ibl e• central parts of the galaxYj по nucleuS v~s s (16~) Very bright spindle with elongated arm

the middlej round in shapej NGC 5929 is small

N.p., S.f.j the arms protrude from an oval tb e shaped envelope with а non-stellar nucl eus ; ut dark Ьanа cuts across the N extension abo

апа

676--~

NGC 6052 6064

vv

86

attached to the S.p. edge of the former.

----_-----------16 04.0

+20 38

14.1

0.9

х

0.56

Her

Two in contact. Distorted. 11

( 60) Faint object about 20

in diameter.

148 \'iS

Cat

149

НА

Dec

rn

AD

СО 11

(NGC 6052 continued). Arp Mkn

209 297

Dec

RA

Cat

AD

(10) А srnall, irregularly-shaped faint patch

10.5 3.0 m Sb:SAB(r)bc. SN: 1971 - 12.8.

of light; it lies а little N of the POsition shown in Atlas Coeli.

(16t)

HGC 6384

16 31.2

rn

+07 05

Соп

х

ОрЬ

3.0

ТЬе centre is bright and extended and

the outer nebulosity appears as arcs of light;

677

NGC 6181

16 31.3

+19 53 11.9 Sc. SN: 1926 - 14~8.

х

2.0

:----

0.7

- - ---

(36) Pretty bright, srnall and oval in

two stars involved to the

Не!'

- - -shape

---681

NGC 6503

17 49.7

+70 09

Н.

10.24

Sc. Possible rnernber of the

with а bright nucleus; а wisp is suspected

11.2

х

М101

group.

4.0

Dra

(16) Bright with almost uniforrn brightness at

ernerging from the Е side; several stars are superirnposed.

LP; higher power shows glirnpses of bright

(16t) Bright central lens around а stellar

patches along the rnajor axis.

(8t) High surface brightness object with well-

nucleus; outer parts slightly elongated.

defined edges; brighter along the centre of

678

HGC 6217 Arp

185

16 33.8

+78 15

11.5

1.8 х 1.2

UМi

the rnajor axis.

Sb:SAB(s)bc. Peculiar nucleus.

-------------

-----

682

NGC 6643

(16t) А little extended Н.р., S.f.; stellar

18 20.5

11.09 5.1 х 2.7 +74 34 Sb. Contains 3 superassociations.

Dra

nucleus in weak nebulosity.

(16t) Elongated H,f., S.p.; the extensions do 679

NGC 6207

16 42.2

+з6

53

2.0

х

0.7

Sb. Lies НЕ of М13.

with

(18) Quite large and bright in РА 450; the although а bright patch lies there; а bright

(12) Fairly uniforrn in brightness; е 1 оп g ated.

is wider

а

dark streak suspected along the f side.

(8t) Fairly bright oval with two stars of about 11.5 rnag оп the \'1 edge; the edges are

nabulosity is fainter S of а stellar nucleuS,

object showed evidence of condensations.

опе

and brighter; the f extension is rnore defined

- - - - - - -- --- - - -

arc is seen Н of the nucleus and the whole

р

not narrow at the ends and the

Her

well-defined with traces of

а

nucleus.

-------------------------

68з

нес

6764

19 07.0

+50 52

14.0

2.1

х

1.0

Cyg.

SB.

(8) Faint with а sudden brightening in the centre to

а

nucleus;

по

other detail seen.

(82) Obviously

а barred spiral,

but the arrn

structure is difficult to see; the bar is

151 150 HS

RA

Cat

m

Dec

AD

cat

Сап

(NGC 6764 continued). narrow and straight and crosses nuclear region with

а

а

small

а

anа

into а second опе which is Бееп аБ а faint

е lЧsht

arc; а third arm is suspected winding W from the centre and this also ЬаБ а knot near its

narrow spiral arms are susp ес t еа;

end with

conspicuous companion lies to the SE and

appears very bright, small, round and with

а

rather like ап irregular planetary nebula; а little brighter towards the f edge.

Sgr

(8) Very faint and formless with по nucleus

the

apparent but two nebulous knots Беет to lie

brightest being IC 1308 and IC 4895. Member

to the "'Т.

of the Local Group. Very difficult due to its low altitude

and the effects of galactic absorption; it appears

аБ

а

686

BL Lac

х51

х102

- - --- -- -

two IC nebulae which, although not extremely

8.9б 14.4 х 12.б

Arp

Sc:SAB(rs)cd. 4С 59.31. Very rich in

29

molecular clouds.

(18) Stellar

-

687

+бо 04

Cyg

NGC 7217

22 об.7 Sb.

---

(30) Very large and faintish with branching arms; а virtually stellar nucleus is at the centre of а weak, elongated structure fro m

Lac

BL Lac. Е galaxy with ап active nucleus. ТЬе

list of additional objects.

but connected regions; по indications of the

20 34.3

12.0 - 15.5

comparison magnitudes, will Ье found in the

faint but БеетБ comprised of three distinct

NGC 6946

+42 01

minimum light. А chart of the region, with

still very

faint, are quite small.

22 00.8

magnitude figures аЬоуе refer to maximum anа

barely discernable nebulous

patch which is extended N-S;

685

stellar core.

it appears somewhat rectangular in БЬаре and

NGC 6822

(8~)

а

(1б~) Quite faint and very large, looking

bright nucleus. 684

(NGC б946 continued). which а long, diffuse arm emerges off the Е knot with а stellar core; this arm branches

.

distribution curves, but not sharply , and lS . weakly enhanced; beyond the latter ext remely faint

AD

end; at the end of this arm is а conspicuous

conspicuous stellar

nucleus; at opposite ends of the bar th

m

Dec

RA

Соп

оп

- - --- - - -

all powers.

+31 14

10.20

7.4 х б.1

Peg

- - - - - - - - - -- - - - - - -

(1б~) Nucleus almost stellar and very bright;

the outer regions appear аБ а small, nebulous glow; а faint star is оп the N edge. (10) Almost round; gradually bright centre.

152 'VIS

688

Cat

НА

NGC 7331

Dec

m

AD

Con

22 35.9

+34 18 9.56 13.5 х 7.0 Peg Sb. PKS 2232+34. Brightest in а group.

----

- - --

NGC 7463

оп the W side; about

11

15

- 20

W of the

22 59.3

+15 42

13.0

3.0

х

Соп

0.5

Peg.

(16) Elongated E-W; quite bright with brighter centre

anа

diffuse edges.

ge е

d

is ап extremely faint, narrow streak , th'1Б

ge

, - - - - - NGC 7464

22 59.3

692'

S.

must Ье an effect of dust; а conspicuous nucleus is centred in а bright bulge.

+15 42

Peg

(16) Small and round with

(16~) Extended with а bright, extended

AD

ш

S.

--

11

153

Dec

- - - - - - - - - - -- - - - - - -- - - - -

(36) Near1y but not quite edge-on' the l' ' , ЧS'ht

distribution is extended with а sharp ed

НА

Cat

attached to the f епа of NGC 746з.

nucleUSj

х160 there is а faint star or nebulous knot near the end of the S.f. extension; the area

between this and the centre is dark.

-69'

NGC 7465 Hkn

313

(8~) х51 а long spindle in РА 1650; there is

diffuse than the р edge.

22 59.5

1.0

13.0

+15 41

:SB.Unconfirmed SN in 1950.

- - - - -

- - --- -

0.7

х

Peg

- - - -

(16) Small, round wi th brighter centre.

gradual central brightening to а very faint ste11ar nucleus; х102 the f edge is шuсh more

а brighter middle;

694

NGC 7469 Arp

298

13.0 1.6 х 1.1 +08 44 Peg. SBa. Class 1 Seyfert. Nucleus а radio source 23 03.0

(6) Fairly bright spindle with mисЬ brighter

and optically variable. IC 5283, 14~8, lies

centre anа well-defined nucleus; the edges

1.3 NE.

,

pass imperceptably into the sky.

(16) Small, faint and round nebulosity of 689

NGC 7335

22

з6.1

S.

+34 19

14.5

1.1

х

0.6

- - - -- - - - - - - - - - -

Peg

(16~) Elongated with S part wider and brighter.

(8~) Appears very faint and slightly elong-

ated; а point source initially.

---------------------------------' 690 Arp

13

Ьу а

----

(36) Pretty bright, small, round, diffuse.

NGC 7448

almost uniform surface brightness; dominated

---

695

bright stellar nucleus.

(8~) Appears at first as а tiny star with the

nebulosity becoming visible after

а

time.

----------------------Ic 5285

23 04.4

+22 40

S. Surrounded

Ьу

14.4 а

1.7 х 1.3

Peg

faint, outer ring.

22 58.8

+15 51 11.2 2.0 х 0.8 Sc. Contains 3 superassociations.

- - - - -- --- --

t (8~) Elongated NW-SE; centre brighter but no

to

а

nucleus; bright star lies close Е.

(8~) Extremely faint and only detectable at LP; ап

11 mag star lies very close due S.

154

155

v/S

696

Cat

НА

NGC 7479

Dec

23 04.7

m

+12 11

AD

11.6

3.0

х

Co n

2.5

Peg

SEc:SE(s)bc.

ge

УУ

SEc:SE(s)c. Contains по definite nucleus.

3.6

And

large integral signj

а

small,

diffuse nuclear bulge shows patchy surround-

сап Ье traced for about 1500 around', оп the S half the bar curves gradually into а

are visible in the outer parts, all of these

ingsj the ends of the galaxy are curved in opposite directions and three or four knots

being extremely faint;

the most conspicuous

brilliant arc which winds about 900., th ere is slight patchiness in the S half of the

is off the S end and appears unconnected to

bar at the point where it curves W.

(16) Elongated, bright and brighter to the

(16~) Quite bright and elongated N.f., S • р.; at ИР the nucleus appears stellar and the

middle; in

S extension is suspected to curve towards а

slightly irregular in brightnessj there is

bright star р; nebulosity also seems to Ье

possibility of the S end being widerj quite

present р а faint star р the nucleus.

faint for

wi th

the rest of the galaxy.

а

bri gh t

с еп tre

j the

ЫЕ

part shows as

а

(8~) Elongated blur of overall luminosity at

а

rich field •

(8~) Rather wispy nebulosity which appears

699

NGC 7678 Arp

sort of light feather.

92

а

shaped like

"

Wl th

(12~) ТЬе main bulk is very conspicuous

Arp

13.5

(30) Eright, very large and extendedj it is

and

NGC 7603

11.0

х

23 20.9

280

+40 42

Соп

stellar core; the N half of the Ьаr 18 . , about 1 long and diffusej а weak 8 " p1ral arrn emerges at а right angle from this half

а

697

AD

m

NGC 7640

(36) А fine asymmetric barred sp1ral; . the bar is bright and crosses а small bul

Dec

НА

Cat

28

а

23 27.2 SEc.

А

highly inclined object.

12.9 1.4

+22 17

х

"1.1

Peg

very large, high surface brightness

spiral arm lies S of the centre.

LP; х102 structural variations seen but these

(30) Pretty faint, small and of low surface

are very indefinite.

brightnessj

23 17.7

+00 07

14.4

1.4

S. Seyfert.

oval of nebulosity.

0.9

- --

----- ------- -(60) Sharp, compact nucleus in

х

а

large ,

peg

а

conspicuous, stellar core is

immersed within опе

side emerges

а

round, diffuse glow; from а

very short arc of lumin-

osity with two patches along its length; it faipt

looks like

а

small, "ring-tail" spiral.

(8~) Lies in а close triangle of starsj it

appears elliptical with and possibly

а

а

brighter centre

more definite SWedge.

а

156 WS

700

157

Cat NGC 7973

RA 23 25.5

Dec +23 20

m

AD

Con

А

Catalogue of Galaxies.

Peg

s.

----

----

(8!) Just visible at LP and ~~ as а very

faint,. elongated blur aligned E-W; possi Ыу а slightly brighter region is associated,

but this is very uncertain with the small aperture used.

. s of 156 Galaxy Fields. Drawlng

159 158

NGC I6 I6-inch

I8-inch

J.K. Irving

8-inch

х

6-inch х65

I20

S. Selleck

NGC 404

NGC 278

2-i-inch х46

б_iпсh х155

Field 411

Field 46'

А.

Goldstein:

Р.

Brennan

х48

Field 301

Field 46'

Р. БrеnnaIiJ;

NGC 147

NGC 55

8-inch

6-inch х65

х202

Field I3'

G.S. iVhiston

NGC's 221, 224 - М31, М32

NGC 185

NGC 23

J.

Тоопе

161

160

16-inch х160

10-inch

NGC 584

NGC 524

NGC 488

NGC's 407, 410, 417

6-inch

х75

2i -inch х4б

х152

Field 41'

Field 14'

s.

E.J. Crick

G.S. Whiston

NGC 520 16-inch

х160

J.

Selleck

NGC 523

NGC 598 - М33

60-inch

1б-inсh

Тооnе

NGC 598 - М33 8~-inch хб4

Field

.Field 14'

G.S. Whiston

D.A. AI:len,

Whiston

D. Childs

162

163

NGC 628 - М74 8-inch

х40

NGC's 7з6, 738

Glyn Jones

779

6-inch х65

Field 14'

Field 46'

Field 14'

G.S. Whiston

Р.

G.S. Whiston

Brennan

NGC's 750, 751

NGC's 760, 761

NGC 891

16-inch х160

16-inch х160

6-inch

Field 14'

Field 14'

G.S. Whiston

NGC 891 16-inch х160

Field 65'

К.

NGC

16-inch х160

G.S. Whiston

NGC 936 2t-inch х46 Fisld 41'

J.

Тооnе

164

165

NGC 972 16-inch х160

NGC 985

NGC 1068 - М77

NGC 1068 - М77

152-inch,

4'!-inch х45

16-inch х160

Field 47'

Field 14'

Field 14'

G. S. Whi st,on

D.A. Al1en

NGC 1023 6-inch х155

Р.

Maloney-

G.S. Whiston

NGC 1055

NGC 1068 - М77

NGC 1343

16-~nch х160

36-inch хз60

8~-inch х102

Fie1d 14'

К.

Read

G.S. Whiston

Field 24'

R.J. Вuta

E.S. Barker

166

167

1C 342

1C 356

8~-inc±1 х204

8~-inch х102

Field 12'

Field 24'

E.S. Barker

NGC 1569

8~-inch х51

E.S. Barker

16-inch х160

Field 45'

E.S. Barker

Field 14'

G.S. \Vhiston

8-inch

18-inch

х80

х202

Field 13'

Field 30'

Р.

NGC's 1587, 1588

NGC 2276

NGC 1637

J.K. 1rving

Brennan

1C 2185,

NGC 2403

6....inch,

16-inch х160 Field 14'

К.

Read

х82

169 168

NGC 2683 NGC 2537

NGC 2403

16-inch х160

60-inch

NGC 2683

6-inch х50

18-inch х200 Field 13'

Field 14' J .К. Irving

D.A. Allen

G.S. Whiston

NGC 2681

NGC 2655

8-inch

10-inch х120

х100

NGC 2693

NGC 2685

10-inch х80

81a-inch х102 Field 241

Field 40'

G. Hurst К.

Glyn Jones

G. Hurst

170 171

NGC 2719

NGC 2782

БО-iпсh

8-inch

Field 45'

D.A. Allen.

Р.

NGC 2787 18-inch

х202

Brennan

1б-iпсh х160

Field 12'

J.

Тоопе

1б-iпсh х160

х100

Field 14'

Field 40'

К.

NGC's 2798, 2799

NGC's 2872, 2873, 2874

NGC 2841

б-iпсh хб5

G.S. Whiston

Glyn Jones

NGC 2903

NGC 2903 12-inch

30-inch

х80

Field 14'

G.S. Whiston

:О.А. А1lеп

R.J.

вuta

173

172

NGC 3031 -

NGC 2985

К.

Glyn Jon:es

Read

К.

х82

NGC 3034 - М82

NGC 3069. 3070

6-inch х115

16-inch х:160

Fi.eld 12 t

Field 14'

NGC 3115,

u 05459

6.-inch х82

8t-inch х111

Field 23'

Field 22'

D. Childs G.S.

~/histon

х80

G. Hurst

1. Read

Read

10-inch

Field 23'

Field

Field 40'

К.

6-inch

б,.. iпсh х115

8-inch.x100

NGC 3079

NGC 3077

М81

175 174

NGC 3412 NGC's 3226, 3227

NGC's 3187, 3190, 3193 16-inch

8~-inc'h х116

х160

NGCfs 3379, 3384, 3389 12-inch х80

16-inch х160 Field 14'

Field 25'

Field 14'

G.S. Whiston S.J. Hynes

G.S. Whiston

NGC 3310

NGC 3344

8~-incb хl02

8-inch

Field 40'

Field 24'

E.S. Barker

х100

К.

Glyn Jon.es

NGC 34146.-inch

х82

NGC )432 8~-inch х102

Field 24'

Field 23'

E.S. Barker

176 177

NGC 34:45 10-inch

Mark 161

х80

G. Hurst

10-inch

G. Hurst

Mark 421 18-inch

х202

Тооnе

NGC з627 - м66

NGC з628

16-inch х160

16-inch х160

Field 14'

Field 14'

G.S. Whiston

G.S. Whiston

• NGC 3623 - 11165

..

NGC 3690/IC б94i

16-inch х160

8!-inch х102

Field 14'

Field 24'

Field 12'

J.

х120

G.S. Whiston

Е.8. Barker

NGC З690/IС 694 60-inch

D.A.

Аllеn

178 179

NGC 3938 8-inch

NGC 3949

х100

Field 40'

NGC 4:038, 4039

NGC 4038, 4039

8-inch х100

6-inch

Field 40'

30-inc:h

х

Field К.

Glyn Jones

К.

Glyn Jones А.

NGC 3992 - М109

NGC 4,026

10-inch х80

6-inch х82 Field 23'

G. Hurst

К.

Goldstein

R.J.

Вuta

NGC 4051

NGC 4:088

16-inch х160

6-inch х50

Field 14'

Field

Read К.

Read

4.7'

181 180

8-inch

6-inob. х155

х100

Glyn Jones

К.

Brennan

D.A. Allen

G.S. Whiston

Read

NGC 4151

6-inch х65

8!-inch x51 Field 45

E.S. Barker

NGC 4244

NGC 4220

NGC 4124 Field 35'

Р.

60-inch

16-inch х160 Field 14'

Field 401

К.

NGC 4214

NGC 4214 .

NGC 4111

NGC 4102

I

8-inch

6-inch х65

х100

Field 481

Field 40'

Р.

Brennan

183 182

NGC 4258

NGC's 4274, 4278, 4283

NGC 4395

8!-inch х102

б-inсh хб5

2i-inch х45

Field 24'

Field 50'

Field 41'

E.S. Barker

Р.

Brenna.n

18-inch

Field 14'

G.S. Whiston

х212

Field 12'

Р.3.

Maloney

Field 50'

Brenna.n

NGC 4449

NGC 4449

NGC 43б9

1б-inсh х1бо

б-inсh хб5

Р.

J. Toone

NGC's 4291, 4319, Mark 205

NGC 4414

3б-inсh хзБО

8!-inch х102 Field 24'

Е.Б. Barker

R.3. Buta

185 184

3С

8!-inch х111

16-inch х160

Fie1d 22'

Fie1d 14'

G.S. Whiston

D. Childs

NGC 4631

NGC 4608

NGC's 4485, 4490

273

8~-inch х102

10-inch х40

Fie1d 24'

Е.Б.

G. Hurst

Barker

NGC 4631 NGC's 4485, 4490 18 -inch

J.K. 1rving

х50

Р.

Brenпan

NGC 4559

NGC's 4627, 4631

6-inch х65

16-inch х160

Fie1d 50'

Fie1d 14'

C.s.

'vlhiston

18-inch

х200

Field 15'

J.K. 1rving

186 187

NGC's 4653, 4666, 4668

NGC's 4656, 4657

6-inch х65

10-inch

х80

Fie1d 50'

Р.

Brennan

NGC 4:725

6-inch х65

18-inch x212

Fie1d 50'

Field 12'

G. Hurst Р.

NGC's 4656, 4657

NGC 4666

16-inch х160

12-inch

Fie1d 14'

G.S. \'/histon

NGC 4725

х80

P.J. Maloney

Brennan

NGC's 4754, 4762

NGC 4826 - М64

6-inch х65

16-inch x160

Fie1d 50'

Fie1d 14'

D.A. Allen

G.S. \'fhiston

189

188

NGC 5055 -

NGC 4958

М6з

6-inch х82

6-inch х65

16-inch х160

К.

Brennan

Read

12t-inch

8-inch

G1yn Tones

Go1dstein

NGC's 5426, 5427

NGC 5406 8-inch

х40

Field 65'

К.

А.

G.S. Whiston

NGC's 5194, 5195 - M51

NGC 5128

D. Dutton

Fie1d 14'

Fie1d 14'

Fie1d 50'

Р.

NGC's 5з6з, 5364 8-inch

NGC's 5194, 5195 - М51

8-inch

Fie1d 50'

.4.. GOldstein

А.

Go1dstein

191

190

М101

NGC 5451 8-inch

х40

NGC 54.51 16-inch

Field 65'

К.

Glyn Jones

х160

Field 14'

G.S. Whiston

NGC 5146 12-inch

М101

х80

NGC 5866

E.S. Barker

Field 14'

Field 14'

G.S. Whiston

NGC 6201

NGC's 5982, 59Е5

18-inch

8~-inch х102

Field 24'

D• .A • .Allen

16-inch х160

16-inch х160

G.S. Whiston

8t-inch х102

NGC' s 5,929, 5930.

NGC 5907

Field 13'

Field 24'

Е.Б. Barker

х200

J

.К.

Irving

192 193

•

NGC 6239 18-inch

NGC 6643

х200

J.K. Irving

Field 24'

E.S. Barker

10-inch

18-inch

х80

Field 24'

E.S. Barker

NGC 6822

8~-inch х102

NGC 7013

8~-inch х102

Field 13'

BL Lac

NGC

J

Field 24

.К.

Irving

NGC 7331

NGC 7217

8~-inch xl02

E.S. Barker

Field 13'

G. Hurst

60946 I

х200

8-inch

6-inch

х100

Field 40'

К. Glyn Jones

К.

Read

х82

195

194

NGC 7448

NGC 74П9

NGC 7479

16-inch х160

8!-inch х102

16-inch х160

з6-inсh хз60

Field 14'

Field 24'

Field 14'

NGC's 7332, 7339

Е.Б.

G. Б. \'Ihi ston

NGC 7469

NGC 7479

8!-inch х204

8-inch

Field 12'

Е.Б.

Barker

R.J.

G.S. \ofhiston

Barker

х100

Вuta

NGC 7640

NGC 7625

S!-inch х51

8!-inch х154

Field 45'

Field 40'

К.

Glyn Jones

Е.Б.

Barker

197

196

PART THREE : LIST OF ADDITIONAL OBJECTS.

ЫСС

NGC 7678

77,41

60-inch

8~-inch х102

Field 24'

Е.Б.

D.A. Allen

Barker

NGC 7814

8-inch

ЫСС

8!-inch х102

х100

Field 24'

Field 40'

К.

Glyn Jones

7973

Е.Б.

Barker

In this section _е have selected Interacting and Pecu1iar ga1axies, ct ga1axies, Seyfert ga1axies and а nитЬег of variable sources. ~~P~o constrictions of space, it has not Ьееn possible to show ~:ding charts for a11 these objects, and consequent1y they аге {l n on1y for 13 Seyferts and 7 variable systems. The Seyfert charts shO-tаkеn from the red (Е) prints of the Pa10mar Sky Survey, and each areers аn агеа 16' х 16', except that of 3С 390.3, оп which а sca1e covmarked. Individua1 sca1es аге a1so marked оп the charts for the 7 iSriable sources, a11 of which, barring 'Н and Х Сотае and АР Lib, "аге ;~oт photographs taken Ьу the 1ate Wa1ter Penne11. The charts from tbe Sky Survey аге reproduced courtesy of Pa10mar Sky Survey Jationa1 Geographic Society. Orientation for a11 of the charts is Jorth ир, East to the 1eft.

198

199

List of Additiona1 Objeets.

List of Additiona1 Objeets.

1nteraeting and Peeu1iar Ga1axies НА

Cat NGC

vv

Arp

NGC Arp

НА

70 166 113

455 164

Dee

m

00 17.1 +29 56 Sb. 1n а eompaet group.

1.6

00 22.3 -00 39 15.4 Туре uneertain. Disrupted.

Ps c

00 24.7 +25 46 14.9 1.9 х 1.з SBO + ? Disrupted pair in eontaet.

And

14.0

01 14.7 +05 03 Рее. Eruptive.

01 56.6 +05 39 14.6 Туре uneertain. Distorted with NGC 1024 Arp 333

х

2.0

2.7

а

02 37.8 +10 44 14.0 Sb. Extreme1y faint spira1 arms.

х

1.0

1.7 х 0.5 long jet. 4.8

х

1.7

2623 79 243

08 з6.9 +25 51 14.5 2.2 х 0.7 Сnе Trip1e system in eontaet. Strong1y distorted with 10ng р1итеэ, rather 1ike NGC 4038-9.

2854 285

09 22.3 SBb.

Psc

Psc

Ari

02 53.9

14.0

-00 17

2944 82 63

09 37.8 +32 25 14.5 1.1 х 0.4 Double system in eontaet. Disrupted.

LМi

09 48.6 +00 44 S. Distorted.

13.5

3239 .263

10 23.8

13.5

Рее. Faint р1итеэ and knots. оп

03 22.4 +00 22 15.3 1.2 х 0·7 Туреэ uneertain. Trip1e group in eontaet. 04 41.8 +00 41 15.3 1.0 х 1.0 Туре uneertain. Compaet with а superimposed star.

Qri

+73 30

13.7

2.7 х 1.0

14.0 gaseous

).0 х 2.3

р1иmе.

NGC 2535

08 09.7 +25 17 13.5 2 spira1s with distorted arms.

9 82

Cet

'fau

07 45.2 +39 05 Е + eompaet objeets in

Arp

1.2

UМa

+17 17

а

еnуе1оре.

з.6 х 2.5

Сат

х

1.5

Sex

5·0 х 4.0

Leo

3.0

х

А star is superimposed

the SE edge.

+ disrupted spira1.

NGC 2444 2445 vv 117 Arp 143 25з6

х

0.5

1.7

+49 19

3023

13.0 Е

07 11.4 Рее. Jets +

vv

1.4

Сnе

08 41.3 +14 23 13.0 з.6 х 1.1 Сnе Sa. Edge-on eompanion with absorption 1аnеэ 1ies е1оэе to the SE. А faint р1ите 1inks both.

02 5 2 • 6 +14 52 14 • 6 1 • О х О. 8 Ari Туреэ uneertain. Double system in eontaet. Distorted. NGC 1143 1144 Arp 118

Сап

AD

m

08 33.8 +24 34 12.9 1.7 х 0.7 SBb. Double nие1еиэ or superimposed star. SN: 1920 - 10.5 mag.

AD

14·5

Dee

14.4

1.6

х

0.7

3ех

3303

10 33.7 +18 16 14.5 Double system with p1umes.

2.5

х

2.0

Leo

3509 75

11 03.1 +04 58 3 рее. Loop.

14·0

2.0

х

0.9

Leo

609

10 24.3 -02 06 3ВЬ. Distorted.

11 0з.6 +40 52 15.0 0.3 х 0.2 UМa 2 objeets in eontaet, appearin~ to Ье аn edge-on and а ring-1ike spirs1.

11 06.0 +18 34 14.7 1.9 х 1.i Туре uneertain. Disrupted with р1итеэ. 11 06.8 Рее + jet.

+53 46

14.1

0.9

х

0.8

Leo

UlVIa

201

200

List of Additional Objeets.

List of Additional Objeets. Cat IC

НА

677

NGC з656 22 Arp 1.55 VY

IC

701

Dee

11 12.6 +12 27 Sb. Distorted. 11 22.2

AD

m

0.8

+53 59

13.4

х

0.45

Douыe

1.7 х 1.7

Cam

11 29.5 +20 з6 Streamers.

Leo

14·7

1.1

х 0.з

NGC 3799 350

11 38.9 +15 28 14.4 0.7 х 0.4 S. NGC 3800, I3.1 mag, is in apparent eontaet NW, and has а high surfaee brightness eentre.

NGC 3808

11 39.5 +22 35 14.1 2.5 х 0.8 Leo Types uneertain. Douы,' distorted system. 2 bridges.

223

23 52.9

+00 16 14·1 Douыe system in contact.

11 41.0 Jets + 11 50.0 Jet +

Рее.

+00 29

13·7

0.4

х

13.7

0.5

х

0.4

0.4

20

Zw

1

Vir

11 56.з +32 25 13.7 1.0 х 0.5 UМa 3. Contains strings of knots like Н II regions which trail along the SE edge.

NGC 3995

11 56.5 +32 26 12.9 S. VY and Arp as for NGC 3994.

2.2 х 0.6

UМa

NGC 4016 Arp 305

11 57.2 3Be/Irr.

1.1

х

сот

IC 883 Arp 193 I Zw 55

13 19.4 +34 16 Jets extend from the

NGC 5614 5615

Zw рluше.

+27 41

13.5

3Е

Воо

0.9

х

0.9

Воо

х

1.6

0.5

Peg

Zwieky Compaet Galaxies

Vir

NGC 3994 249 Arp 313 VY

0.9

Leo

рlиmе.

+00 29

х

еlоэе

3 Рее.

1.0

23 16.7 -04 48 12.8 1.0 х 0.7 Aqr 30 рее. А faint, outer are extends from the N through to the Е.

JGC 7585 jtP

14.2

Соn

AD

m

+26 45 14·3 system with а bridge.

14 59.2 +35 39 Types uneertain. Jets.

Рее. Loop to the S with а very faint outer r" UМa strueture. Fan-shaped absorption aeross the ~ng-like eentre

Рее.

VY

14 33.9

Leo

11 26.1 +79 07 14.7 1.3 х 0.8 Рее. Eruptive or eontaining а jet.

Dee

НА

Сап

0.5

14.8 0.5 х 0.25 and SW edges.

12 23.1 +34 58 12.9 1.0 х 0.8 3а + еоmр. А рlиmе extends from the eompanio n , NGC 5615, whieh is оп the NW edge of NGC 5614'5 spiral arms.

сУn

вой

,

14.5

11

And

00 46.6 +22 14 14.9 Faint рluше extends 30" Е.

16

And

15

Cet

9

Pse

00 14.1 +24 21 Nueleus 3" diameter.

01 20.8

-01 10

43

02 02.5 +04 00 Nueleus 5" х 3"·

53

03 19.4

Zw 372

14.3

Ari

+15 51 15·4 Douыe system 7~5 apart. 04 12.4 +29 06 Nueleus 10" diameter.

15·0

11 Zw

33

05 09.7 -02 43 14.0 High surfaee brightness.

1

Zw

20

08 45.0 +45 53 Nueleus 18" diameter.

Zw

22

08 57.8

Zw

23

10 19.9 +28 03 15.2 2 objects separated Ьу 13"·

+52 23

14.9

14· 9

90

х

30

Таи

26

х

13

Ori

60

UМa

13

Uma

10, 13

LМi

202

203

List of Additiona1 Objects.

List of Additiona1 Objects. Cat

RA

11 Zw 53

11 37.6

1 Zw 40

1 Zw 83 II Zw 70 I I Zw 71

vv

324а,Ь.

Dec

m

Seyfert Ga1axies.

AD

+45 44

15·3

13

12 23,9 2 objects.

+14 53

13.5

12

14 20.9

+45 50

12

Сап

7

х

15·5

10

14 49·9 +35 39 14.5 2 objects both with р1итеэ.

19 13

ВОО ВОО

1 Zw 96

14 58.7

1 Zw 117

15 35.0 +43 35 15.3 12 MCG 7-32-34, а brighter e11iptica1 is 70" NE.

1 Zw 122 1 Zw 125 1 Zw 128

1 Zw 133

+42 07

14.8

х

21

Сот

13

14.0

15

Peg

262 348

00 46.1 +31 42 15.5 Spherical + outer еnуе1оре.

24

And

352

00 57.1 +31 33 15.0 Spheroid with diffuse edges.

15

12

РБе

449 1

01 13.1

+32 50

15.5

27 х 16

РБе

02 46.5

+19 05

15.5

20

х

14

Ari

06 IO.1

+71 03

35

х

23

Сат

ВОО

15.2

13

CrB

3

15 46.8

+37 16

15.2

17

CrB

450

6

15.5

1 Zw 151

16 26.8

39 28

15·4

1 Zw 165

16 47.6

+48 44

14.6

1 Zw 205

18 25.7 +39 19 15.0 The nuc1eus is 10" diameter.

30

I I Zw 136

21 31.2

+10 03

14.6

25

II Zw 187

23 02.8

+22 29

14.7

1 Zw 153

23 20.8 +25 23 Double system 8" apart.

40

х

15

Dra 10

15.0

16 х 12

х

8

Her Dra

10 х

х

20

Сат

06 ~5.7 +54 17 15.5 7 16.5 mag system is in interaetion.

щn

07 43.2 +61 03 14.5 Рее. spira1 with ste11ar eentre.

Сат

06 45.5 Disp1ays

а

+74 29 faint outer

15.0 еnуе1оре.

Dra 374

16 08.3 +41 49 Core is 13" diameter.

Соn

00 03.8 +19 55 Ste11ar in appearanee.

+55 20

10

AD

m

335

15 36.4

15 55.8 +41 57 14.3 С1ОБе to 14 mag ga1axy MCG 7-33-16

Dec

RA

UМa

10

10

Lyr

Peg Peg

382

А

07 52.0

+39 19

08 51.5

+39 44

15.5

20

12

х

7

щn

24

х

18

Lyn

18 45.6 +79 43 13.8 20 Dra Variable, at times reaehing а minimum of 16.2 mag. 23 01.5 Compaet.

+22 21

15.0

15

Peg.

Peg аЬоуе 13 objeets are shown over1eaf~.

205

204

List of Additional Objects •

List of Additional Objects.

.

. .....

"

О,

·.. ·0 , ...

•

! , -•

...... .:_!- ,"

"

....

.

'.

.

'

.

'

... :" 'о

мkn

335

NGC

262

1С

Мkn

348

мkn

Мkn

450 6

9-12-16

12-7-18

.. ~

...-... ..

"

',; :1/11 ",'

..

.

Мkn

352

..

t-"

NGC

449

Мkn

1

"

..... : '\,.", '~",

. '

9-12-16

..

.

....

.

. --

.' . '

." :. .......

0'0

. '

'

.. . . -,:'"

,

-

.

'.

'

• a.,

"

'

I

~

..•

"

.'

..

. ..

.....

374

,

,

Мkn

'

.

. ....

~ ~

.....

Мkn

10

382

7-17-1

10-П-138

5 - 4- 9 .:

о.# ...

',~o

,

-...:.

• • •:

,..

.

••I.. ' "

\

"

'

~:

о'"•

. ....

. .

о.

",

"

.

J

.'

I

..

..... '-

Мkn

Мkn

372 Figure 24.

3

12-6-19

Мkп

NGC 2691

315

II Zw 187 Figure 25·

.

206

207

List

.....

:IJ

t

;-'."\:':--.-."

,'''.'

•

"

.

Additiona1 Objects.

List

..

~

.

••

,; ~'

.-

.'

•

. -. : -,С.

•

..

•

9. •

~

.,

, •• .. . .. ••,.

•

,

08

5

..

.,'" .

"'

* .... '"

..

~,

,/

"•

Additiona1 Objects

In this section we give detai1s of seven variable sources. These is t of оnе QSO, three Seyfert ga1axies and three BL Lac objects • ~tiOns, types and maxima and minima are shown be1ow, whi1e ::~ing charts and comparison sequences appear in the pages fo11owing.

.....'.

.... ~

,

оГ

Variable Extraga1actic Sources •

..

•

#

оГ

•" ~,/

•

•

•

•

• ., • •

.'

•

•

,

.. .. .

•

Figure 26. 3С 390.3. Reproduced Ьу courtesy of М.У. Penston, Ноуа1 Greenwich Obs€rvatory.

••

•

НА

. ...

•• .. '

..

.

. •

Dec

т

тах

т

min

Соn

04 31.8 Seyfert •

+05 18

13.7

14.6

Таи

287

08 53.4 BL Lac •

+20 12

12.0

15·0

Сnс

от

12 20.3 Seyfert.

+28 22

16.5

Сот

231 от

12 57.9 +28 04 16.1 17.2 Сот Seyfert. A1though this reaches а low magnitude at maximum, owners of 1arge te1escopes тау wish to attempt to catch its upper 1imit either visua11y ог photographica11y.

Lib 1514-24

15 16. 3 BL Lac.

-24 16

14.5

16.0

ыь

371

18 07.0 N-ga1axy.

+69 49

13·1

15.9

Dra

Lac

22 01.6 BL Lac.

+42 10

12.0

15.5

Lac

208 209

List of Additiona1 Objects.

List of Additiona1 Objects.

N

,

•

.'

"

,.

"

.

.".

'.

".

.

..

. ',.,.

.

-.

•

д.

D.

'.

G.

•

."

, '

·F

с·

'

-,

Е.

,.

I

Н'

.

'"

.

.

~.

с

.

'

•

'

,

'. А

.

о• •

~

:

,

N

"

;,

Е

•

•

.

.. .', •

О'.,,

.

.30'

.. Figure 27. Finding chart for BW Таи (3С 120). The comparison sequences of stars А, В and С are shown be1ow.

А

В С

т

pv

•

'

••

. ,

,

..

•

• •

• ..

10'

Comparison Stars for BW Таи. Star.

..

...

.

I

."

•

•

.

Figure 28. Finding chart for OJ 287. The comparison sequence of stars А to Н is shown be1ow.

13.6 14.3 15.0

Comparison Stars for OJ 287. Star

т

pv

Star

т

pv

А

l2.9

Е

14.0

в

13.2

F

14.2

С

13.3

G

D

1з.6

Б

14·6 14.9

~

..

210 211

List оГ Additiona1 Objects

List

оГ

Additiona1 Objects

N

•

.С

• •

..

•

•&

А

.1)

• I

•

It~-·-------=---301----;-

---=-_41 ~

Figure 29. Finding chart for W Сот. The comparison sequence of stars А to D is shown be1ow. Comparison Stars for W Сот. Star А в

С

D

т

pg

•

• •

•

.,..

•

•

••

12.67 13.68 14·47 15.30

Figure 30. Finding chart for Х Сот. The comparison sequof stars А to N is shown be1ow. Photograph taken Ьу J. Hoesse1 with the Pa10mar 48-inch Schmidt. Reproduced Ьу courtesy of Н.Р. Green, Steward Obseryatory. еnсе

Star

т

ру

Star

т

ру

Star

т

ру

11.84

F

15.64

м

14.16

14.24

G

17.62

N

17.59

16.14

J

17.71

15.74

L

13.02

212 213 List of Additiona1 Objects

.....

,

.

List of Additiona1 Objects.

" ' N" "

О-о"

.

'-...

..

,

..

".

...

"

. ...

.

..' :

.

....

•

·,0

..

,Е,

,

.

.'

\'

'

,

•

"

','

'.

,

:

'

•

.

" ,

.. .•

.,

,

•

N

.

.. . ..

"

;;'

"

.

,

'

"

"

* '

'.

Е

• .....

•

е.

'. Finding chart for АР Lib. No '1 Ь sequence is aval а 1е for this object.

.

"

•:

..

~

"

• •

~'

.

.

"

,

,

-:, .

~ '" '.~:::

". ~,

'

.

.

..

"

'

••• ',1

... ~: ...

\ Figure 32. Finding chart for comparison sequence of stars

3С А

Comparison Stars for Star.

371. The to G is be1ow. 3С

371. ffi

pv

А

13.5

Е

15.1.

в

14.3

F

15.7

с

14.8

G

16.0

D

15.0

. ,

•

214

215

List of Additional Objects.

00.

"~

..

N

о

•

~

APPENDIX 1.

~

...

о ••

#

.

•

'

....

..

.•

. 0

.0

.. •

.;

.

'.

'.

•

о

•

..

.

..

..

•

0

... .

•.

..

•

8. ~

.

..

•

8•

•

•

,

о

о

\

О

•

'.

\

'

I

/fj 01 ,.I I

I \ \

\0\

"\',

+300 30

°IC 142

IC 142" ..,'\

О.

IC 132

IC 143

{~cl::"--, ...... ...... о

о

;.

•

NGC 60~o

•

О.

.0

о

DIC 133

~

'0

Е

•

°NGC 595

oNGC 588 'NGC 592

О

8

oIC 1~7

IC 139-;D,b

о о

8 о

.

о

•

е

•

•

.... о.е

..-.

.

.

•

.

о

~ о

о

•

е

8 .

•

•;

1.0'

•

•

о

I

Figure 33. Finding chart for BL Lac. The comparison sequence of stars А to G is be10w

3

m

Comparison Stars for BL Lac. Star А

m pv

Star

m pv

12.90

Е

14.28

В

13.26

F

14.42

С

13.43

G

15.48

D

14.10

I

+300 00

8

Figure 34. Positibns of emission regions in From а chart Ьу Rona1d J. But~, McDona1d Observatory, University of Техаэ. Coordinates are for 1950. М33.

217 APPENDIX 2,

. . • • • ,

'

"

.. 8

•

.

•

.

"

.

.·. •

•

'

·

\

'

"

.

.. ••-

-

.-

.'• .

'

·,

•• •••

·•

• •

•

•

"

...

.'

......-. -..

• · ....

• .

•

•••

, ••

.' ., ..... ... . .. · . -. .

,

.'. ·

,

,

'. i. Figure 35, Four brightest Н 11 regions in NGC 6822, The numbers оп the chart correspond to the fo11owing НиЬЫе designations: (2) = НиЬЫе 1; (4) = НиЬЫе 111; (9) = НиЬЫе V; (14) = НиЬЫе Х.

.

•

....

,

••

219 ТНЕ

APPEND1X 3. D1STANCES OF GALAX1ES.

The first distances to external galaxies were derived Ьу НиЬЫе in the rly 1920's, when Cepheid variables in M31 and М33 were used to obtain igures of about 340 kpc. Due to observations Ьу Baade with the 100-inch relector оп Mt. Wilson some twenty years later, it was found that the Cepheids onsist of two types, 1 and 11, and that use of the former to obtain disnces of М31 increased the distance figure considerably. As well as Cepheids, ther types of stars сап Ье used to obtain distances, these being RR Lyrae's, ong-period variables, giant stars in globular clusters and novae and superovae. 1n addition there are Н 11 regions and, leaving individual objects, исЬ parameters as surface brightness, radial velocities, spectral features d sizes. In extragalactic distance determination the first stepping stone beyond Ga1axy itse1f is the Loca1 Group of ga1axies. Here individua1 stars сап е compared with identica1 objects in the Ga1axy, for which accurate abso1ute gnitudes are known. The difference between the apparent magnitude and the bso1ute magnitude (т-М) is the distance modulus; distance figures obtained у this method are known as 1uminosity distances. Ву this method stars in uch Loca1 Group ga1axies as the Mage11anic C1ouds, М31, IC 1613 and the arf systems in Leo, Draco and Ursa Minor have been observed and distances erived, the stars used being classica1 Cepheids and RR Lyrae's. е

Cepheids, however, сап Ье used ир to distances of about 4Мрс (т-М = 28), ich takes in ga1axies outside of the Loca1 Group, a1though sti11 fair1y ar.·1n а11 these cases correction must Ье made for the effects of any аЬ­ orption in the observed ga1axies or a10ng the 1ine of sight to them. RR ~rae stars, not being very 1uminous intrinsica11y, are observable out to light1y 10wer distances than Cepheids in other ga1axies, the limit being f the order of т-М = 22 mag. Fina11y we сап take novae, which сап Ье used as distance indicators out 10 Мрс. 1t is on1y for М31, however, that accurate work оп novae has been arried out, principa11y Ьу Arp, Rosino and Schmidt-Ka1er. Comparison of the 1 distance modu1i obtained Ьу c1assica1 Cepheids and novae shows good greement. Whi1e simi1ar resu1ts are extant for novae in the Mage11anic Clouds, the certainty of the work оп the C10uds novae is not abso1ute. Due о their high intrinsic 1urninosities, novae сап Ье used as distance in~icators for objects in the М81 andM101groups, where their apparent ~gnitudes wou1d Ье between 17 and 18 mag. о

Beyond the Loca1 Group other methods of deriving distances are required; these inc1ude the 3rd brightest cluster ga1axy, the diameters of Н 11 egions, supernovae, galaxy diameters and fina11y radial ve1ocities. е Н 11 region diameter method has been used out to about 10 Мрс, as it Ppears that angu1ar diameters of these emission regions are remarkably irni1ar for galaxies of а given type. An advantage is that по corrections eed Ье made for absorption but there must Ье comp1ete reso1ution in order о obviate seeing effects, and therefore H~fi1ters used in conjunction with arge telescopes are essential.

220 221

Appendix 3. APPENDIX 4.

S~pernovae wou1d appear to Ье extreme " as d1rect comparison with ga1act' 1у usefu1 1n d1stance deriv intermediate st~ps are necessary1CT~upernovae сап Ье achieved, and atio n accurate data оп known .cra1act' . е problem here is the 1ack of 110 1572, for which the most accu~~t:u~efrnovae~ in~1uding the outbur6tV~fry 1n ormat1on 16 a v ai1able 1n conc1uding this brief covera е of " • to the red shift whereby th d g ex~ragalact1c d1stances we to Wh1Ch 6р t 1 l' COl1le th е red end of а ' spectrum is е d' egree t ес ra 1nes are ШО ed diameters, 1uminosi ty c1ass1' f' 1ret~ 1у re1a ted to distance. Н 11 re"'1: to 1са 10nS mass-to l' h t · оп ' d 1a~eters and other methods h Ь' - 1е; rat10s, ga1axy th' ауе ееn used to . t . 1S eff,ect, known a,s the НиЬЫе constant С arr1ve а а f1gure fOr 50 k - М • urrent1y the f' usedmi: ~heP;~s~~t~~~g~u;;~~e~h:ide1Ydifferent from this1~~: b:~:ed i8 at extreme distances, such as thos~a~:~~c:he great~r the redshift, u11til norma11y 10cated in the u1tr . 1 t ~ Ьу QSO э, spectra1 1ines аУ1О е are Sh1fted ' t ' t· th е spectra, as shown be10w in Figure 36. At 1 1n о ор ~ca1 region6 ОГ formu1a for reces6ion of the 1 '. arge redsh1fts the normal . ga аХ1еэ 16 по 1on.cre . Ь1 equat1on, accounting for re1ati . t· f ~ r У1а е, and а new V1S 1С е fects, 1э used. Q

[ож] НЗ

зс 273~

comporisonj Spectrum

НЗ

3889

Д

Ну

Ну

Д

I 6030

The redshift exhibited Ьу the spectra of ga1axies is, as we have ееn, taken to indicate distance, high redshift objects being considerec о Ье at extreme distances, with QSO's being extreme examp1es. For some еаГЭ, however, it has Ьееn fe1t Ьу same researchers that this redshift· istance re1ation is not app1icable in а11 cases, and а great dea1 of ork оп this subject has Ьееn undertaken Ьу Arp ~nd others. As а resu1t of these observations, evidence has Ьееn produced to how that а 1ink seems to show between the companions of 1arge ga1axies nd QSO's, and furthermore that fie1d QSO's, unre1ated to other a1axies, are not the norm. Arp fee1s that~the probabi1ity of аnу 1inef-sight effect with galaxies and QSO's is remote, and therefore that е are dea1ing with physica1 processes, and that the bright ga1axies ct as cata1ysts and eject the QSO's. It is postu1ated that as а resu1t of this the ejected QSO wi11 disp1ay а high redshift and that 8 evo1utionary processes in the object ~ake р1асе the redshift wi11 ecrease unti1, after а 1оnе; period of time, the observed redshift i11 Ье а true distance-re1ated feature of the object. Observations which seem to indicate such processes Ьауе Ьееn made, ,and c011ations of this work show that the high redshift QSO's are situated c10sest to the bright, parent ga1axies whi1e the 10w redshift QSO's appear at 1arger angu1ar diameters from the 1atter, Bringing into the picture the BL Lac objects, the sequence of events is thought to Ъе as fo110ws. Initia11y the parent ga1axy ejects аn object which i8 seen as а BL Lac-type system;ffrom here the object ev01ves into а high redshift QSO of high 1uminosity and fina11y into а 10w redshift QSO of 10w 1uminosity. Examp1es of c10se associations between bright ga1axies and QSQ's are NGC 7413 and 3С 455, ТС 1746 and PHL 1226 and NGC 3079 and Mkn 132.

н,в

5016

NON-VELOC1TY REDSHIFTS.

Д

Figure 36. Spectrum of the QSO 3С hydrogen 1ines with а redshift _273 showing the Ba~mer spectrum is of h d ' Z 0:158. ТЬе compar1son у rogen, he11um and nеоn. (Reprinted courtesy of Maarten Schmidt Н 1 , а е Observatories).

Not а11 cases of anoma1ous redshifts are concerned with ga1axy/ QSO pairings, however. Probably the prime ехатр1е of this is to Ье found in Stephan's Quintet, where the redshift of оnе of the group, NGC 7320, is considerably 10wer than the redshifts of the remainder of the group. Аn interesting group of objects in this context is to Ье found in the neighbourhood оГ the Seyfert ga1axy NGC 4151. These inc1ude NGC 4156, а sma11 e11iptica1 system, а dwarf-1ike ga1axy (MCG 7-25-46), а 1uminosity c1ass Т spira1 and, probably of most interest, аn absorption-1ine ga1axy disp1aying а bright fi1ament оп the end of which is three emission-1ine objects of a1most ste11ar appearance. This association, with the respective redshifts indicated, is shown over1eaf in Figure 39. Arp has pointed out that the region of NGC 4151 appears rich in objects of pecu1iar ~orpho1ogy and anama10us redshifts, and that such аn ama1gam of unusua1 systems is far from uniquitous in the sky.

223

222

A.PPENDIX :5.

Appendix 4.

I11ustrated be10w апа over1eaf are 12 ga1axies from Arp's At1as of pecu1iar Ga1axies. А11 the examp1es shown-are of ob~ects which appear in the preceding cata1ogue, thereby a110wing compa:l~ons. Tbe~ ar~ shO wn in RA order and not as they appear in the orlg lna1 publlcatlon. тЬе photographs are reprirted courtesy of Ha1ton Ar~ апа ТЬе Astro~ysica1 Journa1, pub1ished b~ theC'Un~versity of Chlcago Press; ~ 1966 ТЬе American Astronomlca1 uoclety.

Figure 37. Photograph of Nonequi1ibrium Number 3. Reproduced courtesy of Ha1ton Агр. NGC 2608 Arp 12

ТЬе

amount of materia1 published which is concerned with this topic is considerable, апа we Ьауе по space here to еуеп broad1y cover а11 of its aspects. For those wishing to ае1уе more аеер1у into the subject а review ир to 1976 сап Ье found in Arp, 1976, 1.A.U. Co11oquium No. 37, whi1e for а comprehensive up-to-date survey there is Arp, 1980 in Proceedings 9th Texas 3утр. Re1ativistic Astrophysics (Апп. NY Acad. 3ci., зз6, 1-599). For ап interesting discussion оп the pros апа СОПБ of the subject there is ТЬе Redshift Controversy, Benjamin, 1973·

NGC 3432 Arp 206

2782 Arp 215

NGC 3718 Arp 214

NGC 3445 Arp 24 Fi~ure

JlТGC

38

224

225

Appendix 5.

APPENDIX

6.

111ustrated оп the fo11owing five pages are drawings of six ga1axie made Ьу Rona1d J. Buta using the з6 and 30-inch ref1ectors of the McDona1d Observatory, University of Texas. A11 of the objects depicted appear in the present catalogue and drawings of them with sma1ler apertures have also been shown. Due to the amount of detai1 shown in these drawings, they have been reproduced to the exact sca1e of the origina1s, a1though this wi11 Ье reduced Ьу 10% during the printing process. Detai1s of the telescopes and magnifications used are shown for each drawing.

NGC

4618

Arp 23

NGC 5929-30

Arp 90

NGC

4676

Arp 242

NGC 7603 Arp 92

E'igure 39

NGC

5665

Arp 49

NGC

7678

Arp 28

227 226

Appendix 6. Appendix 6.

• NGC 3646 - 36-inch хз60

.. • •

• NGC 3034, М82 - з6-iпсh хз60 NGC 3893. NGC 3896 - 36-inch хз60

229

228 Appendix

б

Appendix б.

.

••

•

NGC 4485. NGC 4490 - 36-inch х360

NGC

5б27.

NGC

4б31

- 30-inch

х300

231

230

Appendix

б.

APPENDIX 7· FA1NT SYSTEMS NEAH NGC GALAX1ES.

ье fo110wing 41 faint ga1axies have Ьееn observed Ьу Ма1со1m Thompson sing the i5t-inch ref1ector of Westmont Co11ege Observatory, Santa ]arbara, Ca1ifornia. No detai1 is apparent in these objeets, but as sою observers with suitable te1escopes mау wish to attempt observations, WE how these objeets be10w. Their positions re1ative to the nearby NGC a1axies have been measured Ьу Thomson оп the О (Ыие) prints of the Pa10mar Sky Survey. C01umn 'А' gives the NGC ga1axies; 'В' their НА anc Dee; 'С' their magnitudes; 'D' the designation of the faint ga1axies; 'Е' their magnitudes; 'F' their offsets from the NGC ga1axies in НА; 'G' their offsets in Dee. 1n the designations of the faint systems, GCG = Cata10gue of Ga1axies & C1usters of Ga1axies; U = Uppsa1a Cata10gue of Ga1axies and MCG = Morph010giea1 Cata10gue of Ga1axies.

С

В

А

NGC 5I28 -

3б-inеh

OOh06~8

+33 03

262

46.1

31 40

14.0

U 499 (Notes)

01 20.9

33 00

12.8

MCG 5-4-48

16.0

18 f

4'N

507

05 43

15.0

iVICG-1-9-41

16.0

р

1'8

03 27.7

6

1346

73 10

14.0

iYlCG 12-5-6

15.0

р

2' N

04 29·0

1 12

1573

MCG 12-5-7

15.0

48

р

3'8

tl"00065

08 04.8

57 55

14·0

MCG 10-12-80 14.0

2719

57·0

35 56

14.0

MCG 6-20-18

р

2 8

р

5 8

1 00 f

1 8

41 06

14·0

l'IICG 7-~9-39

14 .0

14.2

42 11

13.0

MCG 7-19-54

14·0

6

2798 2832

16.6

33 57

1'3.5

MCG 6-21-24

2863

21.2

10 12

13·0

Uneata10gued

2880

25·7

62 42

12.6

Аnоn

3079

58.5

55 56

11.10

3209 3214 3219

17·8 19·8 19.7

25 45 57 18 38 49

24·5

28 52

15·0

12 15.1

~ime

MCG 9-17-9

15.0

40

MCG 9-17-27

12.0 6

14.7

MCG 10-15-54 14·0

13.9

1IICG 4-25-4

15.2

, ,

,

"р

~ame ее

, ,

3 N р

2 N

24 f 20з68 t 3 N 30 f

,

20 f

1 N

14 .0

MCG 10-15-70 15.0

з6

р

1 8

14.3

lVICG 7-21-49

14.7

11

р

1 N

MCG 7-21-47

14·7

30

р

4 8

15·4

18

р

8 N

3219 3245

30 " 8

~ime

09 12.0

60 29

~ame ее

14.5

2785

10 13·0

ее

з6 f

30

CGCG

~ame

8 f

2521

3168

wJ

15 8

20

3079

N

,

1 24 " р

14I~O

1573

•

13~8

G

,F

Е

D

11.8

Anon CGCG

,

, , I

232 233

Appendix 7. APPENDIX 8. А

В

С

Е

D

3725

11 31.0

+62 10

14~0

3738

MCG 10-17-3

33.1

54 48

12.0

MCG 9-19-125 15.0

3888

45.0

4108

12 04.5

4211

12.9

4741 4834 4926

14~0

F

G

12 " р

I

4 3

Р

8 N

f

48

,

56 15

12.7

MCG 9-19-191 16,0

67

?I)

13.1

Апоп саса

28 27

14.4

MCG 5-29-46

15.5

48·7

47 58

13.2

MCG 8-23-97

1q.0

54.2

18

52 33

15. О

MCG 9-21-71

16.0

2 00 f

15 N

27 53

14 .1

MCG 5-31-107 15.1

12 f

2 N

Uncata10gued

9 f

2 N

Uncata10gued

6

р

1 3

6 f §~~e

59.6

4926 4926

18 f

2 N

6 f

14' N

36 f

2 N

I

1

р

,

f

15 N

, ,

,

13 01.5

28 27

13,3

Щ08167 (Notes)

5975

15 37.7

21 36

14·5

МСа 4-37-21

14.5

21 28.8

12 f

02 17

3 N

14.0

мса 0-55-2

14.0

1 00 f

22 08.0

3 3

40 46

1~·9

Uncata10gued

20.2

35 57

13.0

Апоп саса

7223 7265 7265 7342 7342 7342 7342

35.8

'35

1.2

14.0

3

р

Over the years, тапу photographs of ga1axies have appeared in bookr and journa1s, and а few examp1es of such sources are presented be1ow. For ап overa11 view of most of the sky there are the Pa10mar 3ky 3urvey prints, a1though differing degrees of detai1 are blotted out in some cases, due to overexposure. For interacting and pecu1iar ga1axies there are the respective at1ases of Vorontsov-Ve1yaminov and Arp, to which reference is given in the text. Roberts, 1.

1912, Моп. Not. Ноу. Astr. 72, 408. (NGC 278).

30С.

I

4944 7081

Photographic References.

,

Randers,

а.

1940, Ар. J., 92, 2з6. (мас 488).

Johnson,

Н.М.

1961, Ар. J., 133, 314. (мас 524).

,

40 " N

,

38 f

10 3

, ,

мса 6-49-9

14.0

18 f

1 3

мса 6-49-58

14.0

18 f

10 3

мса 6-49-56

15.0

12 f

мса 6-49-60

15.0

24 f

7 3 , 9 3

мса 6-49-62

16.0

30 f

10 3.

I

,

Zwicky, F. Karpowicz,

1964, Astr. J., 69, 759. (мас 3992).

М.

1965, Ар. J., 142,649. (NGC 972).

Burbidge, Е.М. & G.R. Prendergast, К.М. Kiang.

3imkin,

1967, Ар. J. Lett., 150, 131. (NGC 3353 + Haro ga1axies).

Т.

3.М.

1967, Astr. J., 72, 1032. (NGC 2683).

Vorontsov-Ve1yaminov,

В.А.

1967, in Modern Astrophysics. Gauthier(New morpho1ogica1 types). Vi11ars. 1971, Уо1.

Реппу, A.J. Faira11, А.Р.

Lynds,

В.Т.

РиЬ.

United 3tates Nava1 Obs. Part 1V. (NGC 1569, NGC 6946, 1C 342, 1C 356, 1C 1613, А 1009).

Ables, H.D.

et

ХХ,

1972, Observatory, 93, 27. (NGC 1343). а1.

1973, Ар. J., 182,659. (NGC 4314).

235

234

APPENDIX 9.

Appendix 8. Shostak, G.S.

1973, Astron. & Astrophys, 24, 4i1. (NGC 4236).

Sandage,

1975, Stars & Ste11ar Systems, Уо1. 9. (NGC's 157, 628, 925, 1072, 1300, 1302, 2з66, 2811, 2841, 3185, 3504, з623, 3810, 3898,4088,4293,4395,4643, 4569, 5055, 5204, 5236, 5248, 5273,5457,6643,6814,6951, 7741, 7743, 1С 2574, Но II~.

А.

Kormendy, J.

vVehinger, Р.А. Wyekoff, S.

Arp,

Н.С.

ВIELIOGRAPHY.

C1assifieation.

1977, Ар. J., 214, 359. (Red eompaet ga1axies). 1977, Моп. Not. Ноу. Astr. Soe., 181, 211. (13 Markarian Seyferts). 1980, Ар. J., 239, 469. (NGC 53, NGC 7603, АМ 059-4024, АМ 2054-2210). 1980, Ар. J., 240, 415. (NGC 2859 + eompanions).

Chieago.

INo1f,

М.

НиЬЫе.

Seyfert,

1908, РиЫ. Heide1berg, 19з6.

Е.

С.

Ар. Уо1.

1nst. Konig 3, No. 5·

The Realm of the Nebu1ae.

Уа1е.

1943, Ap.J. 97,28.

Bergh, S. van den.

1960, РиЬ. David Dun1ap Obs. II, No. 6.

Уо1

1962, Morpho1ogiea1 Cata10gue of Ga1axies, Уо1. 1.

VorontsovVе1уашiпоv, В.А.

Krasnogorskaya,

А.

Bergh, S. van den.

1966, Astr.J., 71, 922-926.

Zwieky, Z.

1966, Ap.J., 143, 192. Strueture and Evo1ution of Ga1axies.

Р.

Lequeux,

Page,

М.Н.,

et

а1.

1975, Ap.J., 198,261-266. 1975, in Stars & Ste11ar Systems Systems, Уо1. 9. (Ed. А. Sandage, М. Sandage, J. Kristian).

Т.

А.

1bid.

Shane, C.D.

Ibid.

Kunth, D. Sargent, W. L.iV.

1978, ESO Preprint No. 30.

Sandage,

Gordon & Breaeh.

1974 Ap.J., 189, L5 - L8.

Oke, J.B. Сипп, J.E. U1rieh,

Moseow

Chieago.

Distribution. Materne, J. Peterson,

В.А.

1974, Astron. & Ар., 33, 451-454· 1974, in IAU Symp. 58. (Ed. J.R. Shakeshaft).

Reide1.

237

236 Appendix 9.

Appendix 9. Vaucou1eurs, G. de.

1975, in Stars & Ste11ar Systems Уо1. 9. (Ed. А. Sandage, М. Sandage, J. Kristian).

Chicago.

1976, Astron. & Ар., 49, 129.

Schuster, S. West, R.M.

1979, Astron. & Ар., 71, 131-140.

1bid.

1979, Astron. & Ар., 75, 97-111.

Nuc1ei. Jvior.gan, W. N•

Cesarsky, D.A., et а1. 1977, Astron. & Ар., 61, L31-33.

Kraan, R.

1978, 1AU Symp.77. Reide1. (Ed. Е.М. Berkhuijsen, R. Wie1ebinski).

Ти11у,

R.B. Fisher, J.R.

1bid.

Thuan, Т.Х. Martin, G.E.

1979, Ap.J.Lett., L11.

G.A.

1958, P.A.S.P., 70,

1959, P.A.S.P., 71,394.

Sersic, J.L. Pastoriza,

1965, P.A.S.P., 77, 287.

Arnbartsumian, Sandage,

1966, Trans. 1AU, 12В, 578.

В.

А.

1971, in Nuc1ei of Ga1axies, (Ed. D.J.K. О'Соппе11).

Thomassian,

Р.

Tins1ey,

1969, Structure & Evo1ution of Ga1axies.

Gordon & Breach.

Tins1ey,

1978, in 1AU Symp.77.

Reide1.

Ibid.

Reide1.

U1rich, 1978, in 1AU Symp.77·

Spinrad, Н. Peimbert, М.

J.B.

1971,

Ви11.

1974,

Ар.

J. , 189, L5-L8.

1975,

Ар.

J., 189, 261-266.

Ат.

Reide1

Astr. Soc., 3, 243.

М.Н.

, et

а1.

Reide1. 1976, Q.J. Roy. Astr. Soc. , 17, 227·

Weedman, D.W.

Roberts, M.S.

\Чhitеоаk,

М.

Oke, J.B. Gunn, J.E.

Gaseous and Ste11ar Content.

S.R., et

1970, in 1AU Symp. 44. (Ed. D.S Evans).

1979, Preprint of Ta1k to Roya1 Soc.

В.М.

Visser, H.C.D.

Кnapp,

Со.

Seyfert Ga1axies, QSO's and Re1ated Objects.

Schwarzschi1d,

В.М.

РиЬ.

1978, P.A.S.P., 90, 241-243.

1Vlorgan, W.W. Strom, S.E. Strom, К.М.

N. Ho11and

1972, Ap.J. Lett. 178, L47.

Formation and Evo1ution. Lequeux,

з64.

Л.Л.

1Vlorgan,

Lanstsen, S.L., et а1. 1977, Astron. & Ар., 54, 639. Таттапп,

Hu1st, J.M. van der.

Ke11erman,

1970, in 1AU Symp. 44 (Ed. D.S. Evans).

Reide1.

1975, in Stars & Ste11ar Systems, 9. (Ed. А. Sandage, М. Sandage, J. Kristian).

Chicago.

Уо1.

а1.

К.

1., et

77.

1978, Ap.J., 221, 456.

Rees, M.J.

1978, Observatory, 98, 210-223.

С.

1979, in Active Ga1actic Nuc1ei (Ed. С. Hazard & S. Mitton).

Hazard,

Reide1.

J., 211, 658-668.

Condon, J.J. Dresse1, L.L.

1978, Ap.J., 222, 800-814 1978, in IAU Symp.

а1.1977, Ар.

Osterbrock, D.

1bid.

Cambridge U.P.

238

Appendix 9. Graham, J.A.

1979, Ap.J., 232, 60-73.

Zotov, Tapin,

1979, Ap.J., 229, L5.

Interacting and Pecu1iar Galaxies. VorontsovVe1yaminov, Arp,

В.А.

Н. С.

1959, At1as of Interacting Ga1axies. 1966, Ap.J. Supp., 123, 1-20.

Lynds, Н. Toomre, А.

1974, Ap.J., 194, 569-585.

Thompson, L.A. Gregory, S.A.

1977, PASP, 89,

Fosbury, Н.А.Е. Hawarden, T.G.

1977, М. Not. 178, 473-487.

VorontsovVe1yaminov,

1977, Astron. & 1-118.

Toomre,

В.А.

А.

Ноу.

Ар.

Astr. Soc.,

Supp. 28,

1978, in IAU Symp. 77.

Schweizer, F.

Toomre,

А.

Чеidе1

1bid.

L980, Private

com~unication.

Observation of Ga1axies. Stebbins, J. \Vhitford, А.Е. Petit,

АЫев,

1952, Ap.J., 284. 1954~

Е.

Ho1mberg,

Moscow

Е.

H.D.

Ap.J., 120,413.

1958, Medd. Lunds Astr. Ser. 2., No. 1з6.

ОЬв.

1971, РиЬ. U.S. Nava1 ОЬв., 2nd Ser., ХХ - Part 1.

Webb Society Deep-Sky Observer's Handbook The Handbook is а series of independent volumes addressed to тоге serious amateur astronomers. It is intended to Ье а replacement for Reverend T.W. Webb's Celestial Objects (ог Соттоп Telescopes, pubIished in 1859, which is тоге of historical than practical interest to the amateur of today. It is hoped that the Handbook will епаЫе the user to enlarge upon his abilities, to tackle new feats of observation, and to push his telescope to its limit. Each handbook volume is complete and self-contained with respect to the subject it covers.

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