O'! V" 1956AJ. X 6 o giants ofluminositycomparabletotheAndromedanebula,withresultthatÜ=180km/secper10pc. redshift parameterHisprovisionallyestimatedfrom(a)themagnitudesofresolvedstarsinNGC4321thathavebeen be regardedastentativeuntilWhitford’sresultsareavailableforthespectralenergydistributionofdistantnebulae, greatest distancesattainablewiththelargesttele- relatively smalldistance,heinitiatedanexplora- ized thatthisfirstformulationreferredtoonlya isolated fromtheemissionH11regions,and(b)assumptionthatbrightestfieldclusternebulaeare and untilanadequatetheoryofstellarevolutionisadvancedtoexplaintheStebbins-Whitfordeffect.(5)TheHubble result, theaccuraciesofvariousquantitiesthatleadtoitareexamined.Itisconcludedadecelerationshould redshift-magnitude relationfortheclusterdataconfirmslinearitysmallAX/Xoandshowsanapparentlysignificant The redshift-apparentmagnituderelationisinvestigatedfor(1)fieldnebulaewithandwithoutregardtonebulartype, redshifts for300nebulaeobservedatLick,togetherwithacomparisonofresults114incommonthe observed atMountWilsonandPalomar.Includedinthesedataareredshiftsfor26clustersofnebulae.PartIIcontains The lastofthese(Hubble1953)summarizesthe scope. Thesuccessfuloutcomeofthatprogram distances ofextragalacticnebulae.Sincehereal- nounced arelationshipbetweenvelocitiesand if interpretationismadebytheoreticalequationsduetoRobertson.Becauseofthecosmologicalsignificancethislast departure fromlinearityforshiftsoftheorderAX/Xo=0.2.Thisnon-linearityindicatesdecelerationexpansion cent completetom=12.9intheShapley-Amescataloguefornebulaenorthofô—30.(3)Thelogredshift-magni- selective effectofredshifts.InthefinalAppendixC,aprovisionalevaluationHubbleredshiftparameterHis effect ofdifferentphotometerapertures.AppendixBdescribesthetheoryandcomputationcorrectionfor cussed intwoofthethreeappendices.AppendixAgivesprocedureforcorrectingpublishedmagnitudes law ofredshifts. publication ofhisbook,TheRealmtheNebulae has becomewidelyknown,especiallythrough tory programtofollowtherelationship tude relationforfieldnebulaewithandwithoutregardtotypeislinearwithintheaccuracyofdata.(4)Thelog negligible meansystematicdifferencebetweentheredshiftsfromtwosources.(2)Spectrographiccoverageis63per ity-distance relation,andthelaterfar-reaching observational basisfortheearlyrestrictedveloc- made bytwoindependentmethods. extragalactic researchesthatusedthe100-inch Mount Wilson-Palomarlists.PartIIIisadiscussionofthesenewredshiftdataincombinationwithphotometricdata. to thelimitsofitspowerfor observationsoffaint (2) isolatedgroups,and(3)clustersofnebulae.Theprincipalcorrectionsappliedtotheapparentmagnitudesaredis- pg (Hubble 1936a),andhisprofessionallectures. Abstract. Therearethreemainsectionstothepresentdiscussion.PartIcontainsredshiftsof620extragalacticnebulae The principalresultsofthisstudymaybestatedasfollows.(1)Forthosenebulaeobservedincommonthereisa More than25yearsagoHubble(1929)an- Despite thecomprehensivenessofHubble’s VOLUME 61 © American Astronomical Society • Provided by theNASA Astrophysics Data System REDSHIFTS ANDMAGNITUDESOFEXTRAGALACTICNEBULAE* PUBLISHED BYTHEAMERICANASTRONOMICALSOCIETY GENERAL INTRODUCTION THE ASTRONOMICAL By M.L.HUMASON,N.U.MAYALL,andA.R.SANDAGE JOURNAL 1956 April-No.1237 Founded byB.A.Gould sion, chieflyastheresultofHubble’sinspiring on asystematicbasis,andwithimprovedpreci- data arenowavailableinconsiderablenumbers, influence onhiscolleagues. This unifiedtreatmentofspectrographicand rial redshiftsforover800nebulaeobserveddur- need formanymorenebularredshiftsandmag- a characteristicunderstatement,emphasizedthe variable incorrelationswithnebularmagnitudes. was theiruseasthehigher-precision,independent these redshiftsdoubtlesscouldbediscussed ing the20-yearintervalfrom1935to1955.While nitudes. Thesespectrographicandphotometric nary reconnaissance.”Thisappraisal,although nebulae, heregardedtheminsumasa‘‘prelimi- No. 181.LickObservatoryBulletin, No.542. alone, oneofthemainreasonsforobtainingthem * MountWilsonandPalomarObservatories,Reprint This papercontainsasitsprincipalnewmate- NUMBER 3 O'! V" 1956AJ. X o discussion. 98 was startedin1935attheMountWilsonand a cooperativeprogramofnebularspectroscopy Wilson, thefaintercataloguednebulaeand ago requiredmuchmoretelescopetimethannow, ing totheinstrumentalfacilities.AtMount Lick Observatories.Thefieldwasdividedaccord- pated astheseniorauthorinanalysisand photometric datafollowspreviouspracticeby Redshifts. Thesearesubdividedintothreetables jects forthemoderatecapabilitiesof36-inch of lowsurfacebrightnesswereappropriateob- ural selectionsforthesuperiorlight-gathering faintest andsmallestclusternebulaewerenat- such asthoseinVirgoandComa,thefewer brighter cataloguednebulaeandthelargerspirals power andscaleofthe100-inch;atLick, Hubble, who,hadhelived,wouldhavepartici- fainter nebulaeinthemoredistantclusters.Be- facilitates thetreatmentofmaterialfor These partsmaybedescribedasfollows: catalogue magnitudeof11.6,exceptthatthe arated thenebulaenorthofô=—30at was usedastheprincipalfindinglistandsource Ames CatalogueofBrightExternalGalaxies(1932) arrangement reflectsthebasicprogramsand in clusters,andfaintnebulaeclusters.This that includenon-clusterobjects,brightnebulae more than100nebulaewereobservedincommon. in individualobjectsforspecialpurposes,and of magnitudes.Originally,thetwoprogramssep- cause oftheconsiderablemassmaterial, numerous brighternebulaeinthenearerclusters, three parts,whichwerewrittenbytheauthors fairly widerangeinmagnitudebecauseofinterest progressed, considerableoverlapresultedovera the 100-inchlimitat5=+64°.Aswork Crossley. AtbothobservatoriestheShapley- scopes andwithavarietyofspectrographs which wasobtainedwithseveraldifferenttele- in theordershownbylinefollowingtitle. dispersions, itwasimpracticabletoincludeinthe Crossley wasusedformostobjectsnorthof redshift isgivenforeachnebula. tables allthedetaileddataforindividualplates. are indicatedinasummarycolumn,andmean given inasingletable,because theobserving Instead, thenumberofplatesanddispersions program placednospecial emphasisoncluster nebulae. Sincealltheplates wereobtainedwith Since photographyofnebularspectra20years The remainderofthispaperisdividedinto Part I.TheMountWilson-PalomarListsof Part II.TheLickListofRedshifts.Theseare © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL dispersion (exceptforonenebulaobservedwith volved inlow-dispersionspectroscopyofnebulae. Such informationrevealssomethingofthetech- the sametelescope,spectrographandtwo-prism Photometric Data.Thissectioncontainsquanti- Table Vandnotes,theredshiftsarediscussedfor between redshiftsfordifferentspectralfeatures. and anindexofaccuracybasedontheagreement such detailsasslit-width,emulsion,exposure, three prisms),itwasfeasibletolistforeachplate dix gives,moreover,thelistofcorrectedmagni- with andwithoutregardtonebulartype,(2)iso- with the200-inchandajiggle-camera.Before lated groups,and(3)theclusternebulae.The the Shapley-Amescataloguemagnitudes. in commonatMountWilson-Palomarand nique, observingtime,andorderofprecisionin- cluster nebulaewereobtainedphotographically ford (1952).Themagnitudesforthefaintest cipally fromPettit’s(1954)largecatalogue,sup- redshifts andmagnitudesfor(1)fieldnebulae tative evaluationsoftherelationshipsbetween Lick, and(2)degreeofcompletenessinterms form forthenearerfieldnebulae,andwitha relations givenbyRobertson(1955),insimplified cedure giveninAppendixB.Theredshift-magni- called Kcorrectionswerecomputedbythepro- were madefortheeffectsofredshift.Theseso- other. Additionalcorrectionstoallmagnitudes tudes forfieldnebulae,togetherwithananalysis the proceduregiveninAppendixA.Theappen- the magnitudeswereused,allcorrectedfor plemented withmeasuresbyStebbinsandWhit- magnitudes forfieldnebulaewereobtainedprin- in AppendixCaprovisionalevaluationofthe second-order termfortheclusternebulae.Finally, published precisionphotographicmaterial,onthe and betweenthePettitdataHolmberg’sun- and Whitfordphotoelectricdata,ontheonehand, of theoverlapbetweenPettitandStebbins the effectsofdifferentphotometeraperturesby tude correlationsarediscussedwiththeoretical systems. tance indicatorscalibratedinthenearbyresolved Hubble redshiftparameteriJismadefromdis- extragalactic nebulaeatthe MountWilsonOb- servatory wasbegunin1928 attherequestof (1) systematicdifferencesfornebulaeobserved Following thelastlistofspectrographicdata, Part III.DiscussionoftheSpectrographicand The systematicspectroscopic observationof PART I.MOUNTWILSON-PALOMAR LISTS OFREDSHIFTS 61, No.1237 O'! V" 1956AJ. X o at X4340. became available(Humason1931,1936)when of thenebulae. in nebularspectraandtheapparentbrightness regions anddispersions.Thevariouscombina- are nowfiveBabcock-Swansongratingswhich second. Dispersionsare430A/mmand215 Their focallengthsandFratiosare1.4inches of 3inchesand,asoriginallydesigned,contained Wilson hadbeenmeasured.ThepresentMount 1956 April often usedisEastmanIIa-0andi03a-0.The tions ofgratingsandcamerasprovidedispersions are interchangeablefordifferentwave-length spectra, bothinspeedanddefinition.This, for thedifferenceindispersion,gratingspec- and 190A/mmforthe2.8-inchcamera.Allowing having 600linespermillimeter.Thedispersions and 0.47forone,2.8inches0.95the The Palomarspectrographhasabeamdiameter with theMountWilsoninstruments,asdescribed published. revised valuesforthe146objectspreviously Wilson-Palomar listscontainedinTablesI,II, the redshiftsfor146nebulaeobservedatMount more. from 80to750A/mm.Thetypeofemulsionmost the rulingofseveralmoregratings,untilthere the addedadvantageoflineardispersion,ledto tra compareexceedinglywellwiththeprism been used,bothofthethick-mirrorSchmidttype. mar withaprime-focusnebularspectrograph. and IIIgivetheredshiftsfor620individual he hadfound(Hubble1929)betweenredshifts eras havebeenusedinthetwenty-fiveyearsof perature of65°C,whichincreasestheirspeed then became370A/mmforthe1.4-inchcamera replaced byanewlyruledfirst-ordergrating spectrograph wasmadewhenthetwoprismswere objects, ofwhich474arenew.Theremainder 200-inch. AtMountWilson,thedispersionfor inch and100-inchtelescopesthePalomar some threetimesforexposuresoffivehoursor two 62LBF2glassprisms.Twocamerashave in thetwoearlierpublicationscitedabove.Since Edwin Hubble,inordertotestfurthertherelation June 1950theworkhasbeencarriedonatPalo- 450 A/mmatHy.Almost alltheobservations about 90percentoftheplates isoftheorder the currentprogramwithMountWilson60- IIa-0 platesarebakedfor24hoursatatem- First resultsfromthespectroscopicprogram Up to1950alltheobservationsweremade In February1952animportantrevisiontothe Many combinationsofspectrographsandcam- © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL were madeattheCassegrainfocuswithaspec- long wayoftheslitinaneast-westposition.At trograph whichcouldnotberotated,usingthe which correspondsto12"attheCassegrainfocus position angle.MostofthePalomarobservations have beenmadewiththeslitinanorth-south of the100-inch,andto30"atprimefocus position. Theslitlengthwasusually2.5mm, Palomar thespectrographcanberotatedtoany regions unlessotherwiseindicatedinthenotes. ginning hadbeenpoorlyobserved.(3)Redshifts data wereaccumulateditbecamepossibleto the 200-inch.Observationsareofnuclear final redshifts.Incaseswheretheredshifthad vestigators inthisfieldmayappreciatehavingall local groupareincludedforthefirsttime.(4)In- corrected forthesolarmotionwithrespectto in thereductions.(2)Additionalspectrograms improve upontheinitialwave-lengthsystemused been includedforthefollowingreasons.(1)As and betterplates. were discardedasbeinguncertainenoughtodo been measuredfromunder-exposedplatesoron far belowthoseoftoday.Manytheobjects eras werethenavailableandplatespeeds of extragalacticnebulaewerepoorqualityas are measuredwhentheyappear. known redshiftsavailableinonepaper. have beenobtainedofobjectswhichatthebe- actual harmtothevaluesmeasuredfromlater plates ofverypoorquality,theoldmeasures been re-observedtoreducetheplateerrorsin observed between1928and1935havetherefore necessarily so,asnohigh-speedshort-focuscam- compared withthoseobtainednow.Thiswas at 39337(K),3968.5(H),4101.7Hd,4226.7 the blendedemissionlinesof[O11],absorption spectrograms ofextragalacticnebulaeare3727.3, most oftenobservedandmeasuredonsmall-scale blend. Otheremissionandabsorptionfeatures blend, 4304.4G-band4340.5Hy,4385.0 kilometer. graph slit.Resultsaregiventothenearestwhole measures werereducedtothesun.Allof small ;thetotalrevisionofmanybeingdueonly sun andcorrectedforcurvatureofthespectro- tabulated redshiftshavenowbeenreducedtothe the nearest50or100km/sec.Noneofearlier to thefactthatoldervaluesweregiven Redshifts ofobjectspreviouslypublishedhave Some ofthefirstMountWilsonspectrograms Wave lengthsusedforthereductionoffeatures Most oftherevisionstooldvaluesare Re-observation hasshown thattheformerly 99 X O'!V"

loo THE ASTRONOMICAL JOURNAL 61, No. 1237

km/sec for NGC 6207 (Humason 1936), were UD< LO found in each case to be that of a star projected on the nebula. The redshifts are +960 km/sec for NGC 4569 and +869 km/sec for NGC 6207. The redshift of NGC 6702 is +4749 km/sec; it was formerly given as +2250 km/sec (Humason 1931) ; the early observation was by Pease, who probably observed the nearby nebula NGC 6703, whose redshift is +2,316 km/sec, for 6702. The random errors in the tabulated redshifts of Tables I, II, and III arise from two principal causes. These are (1) the personal error of meas- urement and (2) the error caused by various photographic effects, such as emulsion creepage and graininess. These two effects may be sepa- rately evaluated by analysis of the residuals in the measured redshifts from (1) plates measured more than once and (2) several plates taken on the same object. A formal analysis of all available Mount Wilson spectra with dispersions of ap- proximately 450 A/mm at Hy yields distributions of the residuals which give the probable error of personal measurement, on good to very good quality plates, of the order of p.e. = ±11 km/sec with a total spread of about 5 times this value. The probable error for the plate error is about ±24 km/sec, again with a spread of 5 times this value. Figure i shows the distribution of redshift residuals where two or more good quality plates are available on a given nebula. Since the true redshifts were not known, the mean redshift from Figure I. The distribution of residuals in the measured the various plates on a given object was adopted redshifts for the Mount Wilson-Palomar material when two or more plates are available for a given nebula. The normal error curve is drawn with A[c AX/X0] = o and with dis- persion a = 39.4 km/sec. This corresponds to a probable error of =±=27 km/sec.

published redshifts for five nebulae are in error. They are NGC 1700, 6207, and 6702 in Table I and 4192 and 4569 in Table II. The redshift for NGC 1700 was formerly given as +800 km/sec (Pease 1918; Stromberg 1925); from two very good plates of this object the redshift is now known to be +3,976 km/sec; the reason for the discrepancy in the two values is not known. The redshift for NGC 4192 is —124 km/sec; the former value was +1150 km/sec (Humason 1931) ; the plate from which this value was meas- ured was obtained by Pease and measured by the writer; it is an extremely weak plate and the single absorption feature measured was either incorrectly identified or not real. The negative shifts, —200 km/sec for NGC 4569 and —250

© American Astronomical Society • Provided by the NASA Astrophysics Data System O'! V" 1956AJ. X observed inmanyoftheSbobjectscanbeseen with theplateshavebeentabulatedinstead.The for higherdispersionplates. in PlateIII,ifthespectrumofSbnebula tend toincreasethesizeofestimatederror. observed inmostSbnebulaemaketheirmeas- occur inalltypesbutthewide,shallowfeatures of theSc’s.Exceptionstotheseobservations the absorptionfeaturesarewiderandmorepoorly Sc nebulae.Noticeablelinewideningbeginsto elliptical andSonebulaearenarrowerdeeper indicate thatabsorptionlinesinthespectraof urement onsmall-scalespectramoredifficultand lines are,however,observedinthenuclearregions defined thaninothertypes.Bothwideornarrow appear intheSaobjects.InmanyofSb’s features. TheMountWilson-Palomarspectra of thesefactorsisthecharacterabsorption other factorscanalsoaffecttheseestimates.One is usuallyanindicationofplatequalityalthough size oftheestimatederrorsforsmall-scaleplates expected tobewithin5X35=175km/secof The conclusionfromthisformalanalysisisthat error. Forpoorqualityplatestheprobableerror comparable spectraltype.Linesinthespectrum four timeswiderandnoticeablyshallowerthan spectrum oftheSbnebulaareestimatedtobe at MountWilsonunderexactlythesamecondi- than theyarefortheSa,Sb,andsomeof involved, estimatederrorsbaseduponexperience realistic duetothesmallnumberofobjects all tabulatedredshiftsofTableI,II,andIIIare those observedinanon-rotatingstellarsourceof tion featuresareobvious.Absorptionlinesinthe tions anddifferencesinthewidthsofabsorp- NGC 221.Spectraofbothobjectswereobtained of thetabulatedvaluesisabout±35km/sec. formal probableerrorof=±=26.6km/secforthe but theeffectshouldnotbeserious.Thenormal and residualsfromthemeancomputed.This km/sec oftheirtruevalue.Theerrorsaresmaller plates. Itisthecombinedplateandmeasuring zero andwitha=39.4km/sec.Thisgives error functionwasdrawnwiththemeanequalto 1956 April of theellipticalnebulaareapproximatelytwo NGC 224iscomparedwiththatoftheelliptical tabulated redshifts,forgoodtoveryquality procedure tendstosymmetrizethedistribution, their truevaluewithmorethanhalfwithin35 Sb nebulaethelinesareagain aswidethose times widerthannormalstellarlines.Insome observed inNGC224.Itis probablethatwiden- Since thisformalanalysisissomewhatun- A typicalexampleofthetypelinewidening © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL velocities andspectraltypes,thatthischar- Table Icontainstheredshiftsfornon-cluster extragalactic nebulaeiscausedbyamixtureof acteristic islesspronouncedintheellipticalandSc ing oftheabsorptionfeaturesinmany objects. Amongthenebulaedesignated“anony- shown inTableIVBwereestimated. members ofclusters,butlaterfoundtobefield brighter nebulae,mostofthembeingNGCorIC nebulae andgroups.Ingeneraltheyarethe separate thenon-clusterandclusternebulae. been subdividedintothreegroupsinorderto do appeararegoodindicatorsoftype.Neverthe- nebulae thanformanyoftheSb’s,andsomeSa’s. mous” areseveraloriginallyobservedaspossible especially forsomeoftheSbobjectshavingwide past (Humason1936).Althoughabsorptionfea- have beenestimatedinthesamewayas those obtainedfromclustermembers. nebulae withredshiftsnotinagreement show X3727,ifpresent,thepercentagefrequencies spectra wellenoughexposedintheultravioletto The pictureisnotgreatlychangedfromthatof groups, notgreaterthanone-halfadivision. tures insmall-scalespectraarefew,thosethat of brightnebulae.Mostthemarecatalogued nor changedthepercentagevalues.From278 each groupisshowninTableIVA. one-half ofaspectraldivision;fortheother lines. Forthese,theerrorisprobablylargerthan less theaccuracyofestimatesisnothigh, objects. AlltabulatedredshiftsinTableIIare estimated byMayall(1939)andHumason distribution oftheSc’sisalmostuniformbetween against Hubble’sdeterminationsofnebulartype. from TableIandIIhavebeenplotted smaller than+12,000km/sec. the numberofspectraavailableforinspection, in thespectraofextragalacticnebulaehasbeen increases towardearliernebulartypeuntilthe elliptical nebulaehavebeenclassifiedasG.For sec. nebulae withredshiftslarger than+12,000km/ types FoandG3.Themeanspectraltypefor the 1936plotwhenonly136objectswereshown the spiralsnumberofblueobjectsgradually (1947). Thenewdatahavenotgreatlyincreased (Humason 1936).Withtheexceptionoffour,all The frequencyoftheoccurrenceX3727[011] The MountWilsonandPalomarredshiftshave Spectral typesofnebulaeinTablesIandII Table IIcontainstheredshiftsfromclusters In Figure2thespectraltypesof546nebulae In TableIIIaretheuncataloguedfaintcluster 101 1956AJ 61 . . . 97H 102 * 10 *1613 7814 *IC NGC Anon Anon Anon Anon Anon 0) 205 221 214 247 227 224 127 125 379 375 357 300 253 157 128 383 382 380 388 386 385 384 160 278 474 404 488 194 182 495 185 185 499 514 507 560 524 598 596 564 584 45 55 23 604 68 69 71 72 16 83 80 © American Astronomical Society • Provided by theNASA Astrophysics Data System 0* R A (2) 11.4 32.2 -840 26.1 25.2 12.5 -3930296-77 26.3 +234 15.8 33.4 +2341 26.6 +236 15.8 35.6 26.7 +235 15.9 15.8 40.0 38.8 37.6 36.7 36.2 36.1 16.0 40.0 17.5 47.1 45. 1 44.5 40.1 18.8 18.6 47.1 52.7 49.2 20.1 +3313 20.8 20.4 21.4 6.5 31.0 30.3 22.3 31.7 24.9 7.3 28.8 25.2 17.4 +39 0^7 19.2 +50 4.6 4.5 +3215 4.7 4.6 4.5 +3213 4.3 +325 0.8 -637 5.0 +323 4.7 2.5 +152 6.6 +3527 4.6 1950 +25 39 +27 27 +i5*5r +29 46 +29 48 -23 27 +29 46 +29 46 +29 47 +59 2 +22 5 +22 25 +22 9 + 240 + 228 +48 4 +41 0 +40 36 +25 14 +41 25 + 246 +48 4 +47 17 +42 20 +42 19 - 148 +32 +32 +32 +32 -21 2 +32 -25 34 -37 58 +33 0 +33 12 +12 39 + 917 +30 24 +30 32 -2 11 -77 - 29 - 717 Dec (3) TABLE I.REDSH1FTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS 259 105 Long Lcrt 103 76* 30 80 80 83 107 83 83 83 107 106 104 113 83 114 87 102 121 120 83 83 85 82 82 82 82 89 87 87 82 89 89 87 89 89 89 89 94 102 91 91 91 95 95 99 95 95 95 95 95 95 95 95 99 99 99 (4) (5) Gal THE ASTRONOMICALJOURNAL61,No.1237 -34 -45* -36 -82 -32 -32 -32 -32 -32 -40 - 3 -40 -60 -40 -60 -60 -37 -60 -14 -14 -71 -21 -60 -37 -59 -22 -30 -83 -64 -21 -30 -15 -80 -20 -20 -30 -30 -30 -30 -60 -69 -26 -30 -30 -30 -28 -56 -58 -28 -28 -49 -63 -52 -67 -31 -31 -67 -62, Neb Spec SB0 Sa Sb Sc E2 G3 SB0 G2 SO G3 E4 G3 SBa G7 SO Sc E0 SO Sa Sb SO Sa Ep Sa Sc (6) (7) Sa SBO A8 El G5 E4 Sb E2 Sc Sc E2 E5 Sc Sb Sb Sc EO E2 E3 E3 E3 SO SO SO SBa G4 SO Irr EO Sb SO SO Sc E3 SO E3 SO EO E3 Sc Sc Type G3 Em Em F5* G5 Em GO* G3 G5 GO GO* G5* G4 G7* F8 G8 GO G4 G3* Em Pm G3 F0* F3* G3 G5 Em Em G5 G5 G6 G2 G1 GO G5 G5 F8* G5 G5 G7 G5 G3 G5 A7 GO G7 G1 G3 Em G3 G5 G4 Redshift + 1,047 cÄVV + 450 + 4,568 + 3,110 + 210 knrv/sec + 6,637 + 5,787 + 6,807 + 6,591 + 6,976 + 6,541 + 5,586 + 4,460 +37,052 + 4,250 + 5,289 - 343 + 5,255 + 4,094 + 5,234 + 1,826 + 4,535 + 5,105 + 5,315 - 344 - 266 + 248 +23,908 +60,980 - 239 + 5,156 + 4,341 + 5,374 + 6,011 + 2,541 + 622 - 266 - 214 + 5,555 + 4,845 + 4,401 + 4,888 + 5,114 + 2,180 + 2,306 + 4,375 + 4,114 - 55 - 238 + 4,929 + 2,487 + 5,503 + 2,470 + 5,851 + 2,049 + 1,827 - 226 - 189 (8) 81 28 Redshift DIspError + 4,790la + 3,335la + 1,2452a + 177la + 488la km/sec + 6,862la + 6,012la + 7,032la + 7,201la + 6,816la + 5,790 + 4,594 +37,251 + 6,745 + 5,423la + 1,913la + 4,3842a + 4,2282a + 5,4561a + 6,209 + 2,613 + 200 + 854 +24,136 + 4,599 + 5,354 + 4,539 + 5,572 +61,208 + 2,4022a + 152lb + 5,753 + 5,043 + 5,086 + 5,312la - 130 + 4,306la + 2,282la + 2,616 + 5,121 + 4,567 + 5,578 + 2,587 + 1,878 + 5,923 + 2,097 - 49 ■ 5,237 • 102 • 5,360 Corr PitsEst (9) (10)(11) 5,423 4,731 35 24 72 17 12 8 1 3b lb la la la la la 2a 2a 2a la la la lc,3d la la, lb la la la la lc,3d la la la lb la la la la la 2b la la la lb, 1c kny'sec 100 150 150 150 130 100 150 250 100 150 150 100 50 150 50 30 50 150 100 150 65 60 150 150 40 50 50 50 50 50 50 75 35 65 50 30 35 12 30 65 50 40 40 50 30 50 40 12 50 15 50 10 60 50 65 10 65 75 15 12 Absorption linesarebroadandIndistinct. This andnextfouraremembersofagroup. Em patch217pnucleus,oftwo.ObservedbyHubble. Bright empatchOi8nfnucleus. Br empatchinsfpart.Possiblememberlocalgroup. This andnextonearemembersofagroup. Brighter andpof3faintneb.1J3sfNGC72. See note1atendoftable. Member localgroup. Neb 5:6n,9i5pNGC128. Member localgroup. See note2atendoftable. Member localgroup. Member localgroup. Globular clusterinNGC185.111sfnucleus. This andnexteightaremembersofagroup. Bright empatch510sfnucleus. One platebyHubble. For thisandnextoneseenote3atendoftable. Em patch217nofnucleus. Brighter oftwoempatches218spnucleus. Absorption linesaresomewhatbroadandshallow. Em patch019s,10!8fBD+1°200.Memberlocalgroup. Absorption linesareindistinct. Absorption linesaresomewhatbroadandindistinct. This andnexttwoaremembersofagroup. Member oflocalgroup. Em patchinNGC598. O'! V" 1956AJ. X 1956 AprilTHEASTRONOMICALJOURNAL *1727 * 342 *IC NGC Anon For 1023 1003 1049 1079 1068 1052 1087 1407 1097 1084 1317 1316 1156 1140 1417 1399 1395 1380 1332 1302 1209 1201 1199 0) 1439 1426 1415 1400 1404 Anon 1451 1449 1441 1453 1569 1521 1587 636 1600 628 1637 1601 736 720 681 1700 741 788 772 751 750 972 891 890 821 936 925 © American Astronomical Society • Provided by theNASA Astrophysics Data System h 34TO R A (2) 36.6 44.7 46.7 50.6 53.8 +523122 53.8 +3248107 54.6 +3258107 56.6 +1846113 54.6 +3258107 58.6 -73135 34.6 +3412115 31.3 +296117 24.3 +3321113 36.1 +4039112 25. 1-22137 37.2 +3851113 37.7 -3429202 19.3 +427108 38.6 -828150 38. 1-3441202 34.6 41.6 -2913189 38.8 36.9 36.6 36.3 56.7 +252125 52. 1-1014156 43.9 -042142 43.6 -747151 40.3 -013141 19.3 +332112 37.9 37.3 44.2 -3029193 39.5 24.1 20.8 20.8 40.6 43.6 43.2 41.9 43.7 44.0 42.6 17.7 26.0 38.9 38.1 28.1 54.5 29.2 29.2 5.7 +1045120 3.7 2.0 6.1 1.3 1950 +27 5 - 746 -10 40 -13 59 -26 15 -23 11 -21 31 -15 48 -35 9 -37 17 -37 24 -26 14 -15 47 -18 44 -35 45 -35 37 +67 57 -22 16 - 452 -22 42 -18 51 - 415 - 413 -22 4 + 033 +64 45 - 47 - 417 -21 11 + 49 - 512 - 510 - 456 - 257 Dec (3) TABLE I.REDSHIFTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS 125 108 107 143 135 206 206 204 202 203 187 185 167 167 177 160 177 183 179 182 183 160 182 106 160 160 Long Lot 160 184 111 168 162 168 160 171 167 (4) (5) Gal -66 -45* -33 -69 -67 -53 -27 -26 -26 -40 -47 -25 -63 -24 -17 -63 -50 -63 -51 -56 -64 -64 -18 -17 -23 -27 -54 -28 -55 -60 -56 -55 + 11 -52 -52 -50 -53 -53 -56 -56 -56 -55 -49 -49 -42 -50 -50 -41 -41 -49 + 12 -41 -41 -43 -29 -32 -32 -26 -29 -25 El Neb Spec Sc E5 Sa Sc E0 E0 El E0 Sb E6 Sa Sc Sb SO E3 Ep Ep SB0 G5 Sc F0* Sb F3* SBa G3* SBa F8 SBa G3 Sb SBb F8 Sc Sc E6 E3 Irr E2 E2 SO Irr El El SO Sa Irr Sa (6) (7) EO Sa E4 Sb Sa EO Sc Sa SO El E3 E3 E5 El Irr SO E3 Sc Sa Type F5* Em G5 G4 G5* G5 G2 G2 G7 G4 GO" G4 G5 G1 F0 F0* F7 Fo" F5 G5* Em F2" F0 G5 G4 G2 G3 G4* G2 G7 G5 G2 F8* G4 G4 G4 GO G4 G3 G5 G3 G2 Em G5 GO* G2 G5 F8* G7 G2 G5 FO" G4 + 1,941 + 561 Redshift + 1,750 + 362 + 1,808 km/sec + 5,559 + 5,130 + 4,366 + 2,431 + 5,126 + 1,778 + 4,137 + 72 + 4,043 + 1,538 + 420 CÀVX + 557 + 4,800 + 1,343 + 35 + 585 + 1,439 + 40 + 1,020 + 1,824 + 1,558 + 2,252 + 1,544 + 1,326 + 2,568 + 405 + 1,878 + 1,730 + 1,722 + 2,581 + 1,458 + 1,856 + 1,690 + 1,609 + 2,060 + 1,811 + 483 + 4,101 + 1,508 + 2,044 + 1,358 + 3,927 + 4,176 + 4,262 + 1,997 + 4,222 + 3,919 + 3,890 + 4,600 + 4,997 + 4,830 - 34 + 3,976 + 695 (8) 10 + 1,983 + 687 kn\/sec Redshift Disp + 1,768 + 518 + 1,814 + 4,528 + 5,295 + 5,637 + 5,291 + 2,553 + 4,161 + 4,193 + 1,865 + 246 + 564 + 1,664 + 1,367 + 709 + 741 + 4,938 + 1,4243a + 1,540 + 2,156 + 1,224 + 1,835 + 495 + 1,511 + 1,573 + 1,507 + 1,913 + 1,728 + 1,616 + 2,502 + 1,626 + 2,518 + 1,302 + 1,388la + 1,706la + 1,706 + 1762b + 4,044la + 3792a + 1,885la + 4,202la + 1,878la + 1,241la + 3,867la + 4,116la + 3,8593a + 4,060la + 3,812la + 1311b + 4,531la + 4,895la + 4,728la + 3,8592a + 5962a Carr Pits (9) (10) 1,032 76 71 2a 2a la la la la 3a 2a 1b la la la la la la la la la 1b 2a la, 1b la 1b la, 2b la la la la la la la la la la la la la la Error kn\/$ec 01) 200 100 150 200 100 250 100 200 150 200 100 100 100 150 50 Est 150 50 50 100 60 100 40 40 50 60 100 65 65 100 60 50 60 30 60 40 60 40 40 40 50 40 75 50 75 50 50 50 75 50 40 50 20 40 75 30 50 75 50 40 50 Em patchinsfendofIC1727. p neb.Thisand751appeartobephysicallyconnected, f neb.Formsclosepairwith750. Abs. linesaresomewhatbroadancTshallow. Abs. linesarenarrowandweak. Abs. linesareweakandshallow. Abs. linesarebroadandindistinct. Observed andmeasuredbyMinkowski. Bright clinForsyst.Memberoflocalgroup. One platebyHubble. Faint clInForsyst. Two empatchespcenterofneb. Abs. linesareweak. Both abs.andemlinesarebroadindistinct. Observed byHubble. Observed byHubble. Observed byHubble. Observed byHubble. Observed byHubble. Lines aresomewhatbroad. Possible memberoflocalgroup. Em patches,p.a.slit112°.ObservedbyMayall. Abs. linesarebroadandshallow. Brightest nebinvicinity. Pease vel+800.Pease,F.G.19î8,Pub.A.S. P.,30,255. 103 1956AJ 61 . . . 97H 104 .2950 2207 214Ó NGC 2314 2217 *IC 2379 2300 2339 2549 2535 2403 © American Astronomical Society • 2613 2562 2537 2532 2460 2563 1889 1832 2655 2623 2608 2673 2672 2639 2654 Anon Anon 2716 2694 2685 2681 2683 2855 2841 2832 2831 2723 2712 2693 2859 2787 2811 2782 2768 2775 2749 2744 2880 2798 Anon 2865 2903 0) 2914 2911 3003 2964 2986 2983 2974 R A (2) 32.0 20.3 52.7 31.2 24.2 32.2 35.4 40. 1 53.5 52.2 50.0 49.6 49.2 46.6 10.7 55.4 55.3 55.0 53.5 46.5 44.3 14.2 57.7 56.2 16.5 19.7 15.0 17.5 17.7 21.2 31.0 21.3 31.4 39.0 25.7 29.3 40.0 13.9 40.0 14.9 14.4 11.0 41.8 41.3 18.6 16.8 16.8 15.7 45.6 19.1 3.8 979 5.4 8.2 7.0 9.7 7.8 7.7 2.5 1.8 1950 +78 23 +65 43118 +18 52165 +75 19107 -11 32 -IS^Ó' +33 55153 +85 4995 -21 21 +60 31124 -27 13 +57 58127 +46 9141 +25 22165 +34 6155 +21 18170 +28 38163 +21 14170 +50 23136 +25 56167 +51 33134 +58 59125 +51 30134 +33 37158 +19 16175 + 715191 +18 31178 +18 40178 + 323 +45 6 + 321 + 317 +51 32134 +78 25102 +19 16175 +60 28123 -22 48213 +42 10147 +60 15122 + 323 +40 19149 +51 12134 +33 59159 +33 59159 +69 25111 -11 53211 -16 6214 +34 44158 +62 44118 +10 22191 +21 44177 -22 58221 -11 41212 +10 20191 +32 5162 +59 5122 +33 39160 -20 14223 - 329208 -21 3223 Dec LongLaf (3) (4)(5) TABLE I.REDSHIFTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS 202 181 103 184° 196 194 143 194 194 194 THE ASTRONOMICALJOURNAL61,No.1237 Gal +26 + 14 +28 +28 -23 +23 -16 -27° +30 -17 +32 +32 +35 +35 +30 +30 +36 +30 +41 +40 +40 +33 +36 +36 +39 +35 + 12 +31 +31 +31 +41 +41 +40 +35 +39 +31 +42 +46 +23 +45 +42 +39 +45 +46 +26 +39 +47 +20 +27 +46 +43 +42 +42 +46 +46 +25 +36 +52 +25 +51 M E0 G2 Neb Spec Sap F0" Sb G4 E3 SBa G2 Sc Gl* El E0 Sb Sc Sc Sc Sb SO Sb SO G2 Sa G5 El SBc A5* Sa F5 Sb Gl E0 G4 E2 G2 S0p Gl*+1,2991,473 E0 Sa Sa Sa F8* SOp G5* Sa Sb E2 GO* Sb F8 SO G2 Sb F5* Sa Gl El G5 Sa F0" SO G5 Sa G3 E2 GO SO F5* SBa G5 SBa F5" Sa G3 E4 G2 SO G3* Sb GO* (6) (7) SB0 G3 SBb Gl SOp F8* Sc F0* SB0 G4 SB0 G2 Sa F8 SBa G5 E4 E2 G7 Sc Sb F0* Type G5 GO* F2* Gl G5 Em F5* F8* G2* G4 F8 GO* G3 G4 G5 G5 F5" G5* + 2,037 + 2,361 + 785 + 2,472 càVK Redshift + 3,843 + 1,585 + 4,030 + 1,946 + 2,680 km/sec + 70 + 5,153 + 1,442 + 397 + 4,243 + 2,1192,041 + 4,963 + 1,082 + 5,4355,342 + 1,710 + 4,775 + 4,2234,100 + 1,3601,450 + 3,3143,350 + 1,135 + 4,2034,076 + 3,7253,530 +20,575 +20,380 +30,403 +30,208 + 5,1235,165 + 6,946 + 5,1555,104 + 16,160+15,914 + 639 + 2,514 + 2,5172,502 + 3,4503,325 + 3,5373,342 + 4,9564,998 + 1,6941,649 + 1,908 + 584 + 1,708 + 1,8401,849 + 2,7142,441 + 642 + 1,514 + 3,3703,208 + 1,4301,512 + 2,013 + 1,340 + 3,1402,978 + 1,476 + 2,0151,748 (8) 3,792 +3,669 1,408 2,397 336 884 703 Provided bythe NASA Astrophysics Data System + 2,310 + 1,869 Redshift Disp + 2,262 + 2,455 + 965 + 3,994 + 4,005 + 1,345 km/sec + 5,111 + 2,150 + 4,153 + 187 + 1,438 + 1,157 + 415 + 1,533 + 4,664 + 4,852 + 1,497 + 6,895 + 1,652 + 625 + 1,797 + 1,286 Corr Pits (9) (10) 2,256 1,699 2,130 1,616 1,428 961 748 285 768 958 531 3a 3a 5a 2a 2a 2a 2a 2a 2a 2a, lb la la, lb la la 2a la la 2a, lb 2a la la la la la 1 a,b lb la la la la, lb 2a la la la la la la la la km/sec Error 200 ObservedbyHubble. 150 ObservedbyHubble. 200 (H) Est 100 100 175 100 100 100 100 30 50 40 65 30 60 pnebofclosedouble.Abs.linesareweak. 40 50 50 40 40 50 50 75. 30 65 65 65 40 75 65 75 20 50 50 50 40 65 50 50 75 65 60 40 75 40 40 50 75 75 20 65 50 50 75 50 50 75 60 50 Abs. linessomewhatbroadened. One platebyMinkowski. This andnextonearemembersofagroup. Observed byHubble. Brightest empatchnpcenter. Abs. linesareveryweak. Observed byMinkowskiaspossibleradiosource. Abs. linesareweakandpoorlydefined. Observed byHubble. This andnextonearemembersofagroup. Abs. linesarewideandrathershallow. Abs. linesareveryweak. X3727 strong.Linesshowrotationalinclination. Abs. linesshallowandnotwelldefined. Observed byHubble. One platebyHubble,oneMinkowski Observed byMinkowskiaspossibleradiosource. Observed byHubble. For thisandnextoneseenote4atendoftable. Abs. linesbroadandnotwelldefined. Abs. linesareweak. Abs. linesareweak. 1956AJ. 1956 April 3034 3032 3067 3031 3115 3078 2985 3245 3147 3158 3162 *IC RADec NGC 1950 3177 3169 3166 Anon 3190 3184 3135 3254 3226 3193 Sex Sex 3344 3301 3277 3227 3222 3348 3351 3310 3367 3384 3379 3377 3368 3414 3412 3556 3516 3521 3504 3489 3486 3585 3607 3605 3593 Anon Anon 3608 3613 3611 (1) (2)(3) 3610 3623 3619 3626 3640 3627 3642 American Astronomical Society •Provided bythe NASA Astrophysics Data System h 10 9 46?b 51.5 49.2 51.9 55.4 52.8 56.2 34.2 30.3 26.5 20.7 41.3 40.8 35.7 24.5 20.7 11.7 10.9 10.8 13.8 12.8 11.2 45. 1 44. 1 44.0 43.4 48.3 45.7 45.2 15.7 15.4 15.2 14.9 57.7 55.4 48.6 57.7 19.8 10.9 14.2 12.0 14.3 14.4 15.6 14.9 8.7 15.7 16.5 16.3 8.7 2.8 17.5 18.5 17.6 19.5 3.4 3.3 0.5 8.6 1.0 +69 18 +72*31' +69 56 +32 37 + 837 +29 28 +39 1 +22 59 - 428 - 728 -26 41 +73 39 + 343 + 340 - 428 +21 56 +21 23 +22 5 +41 40 +20 9 +20 8 +22 9 +20 7 +28 47 +29 45 +28 46 +53 46 +22 9 + 1158 +25 11 + 1415 + 125 + 141 +73 6 +57 3 +28 14 + 1341 + 1254 + 1251 + 1410 +29 15 +55 57 +72 50 + 014 +41 5 +28 15 + 135 + 1817 + 1819 -26 29 + 450 + 1826 +59 4 + 1322 +58 17 +18 38 +58 2 + 331 + 1316 +59 21 TABLE I.REDSHIFTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS Long Lot 216 +38 230 +22 215 +41 215 +41 207 +47 19/ +46 108 +41 109 +42 168 +52 106° +39* 207 +47 162 +54 150 +57 179 +56 103 +40 203 +58SBbF5 182 +56 203 +59 200 +60 200 +59 145 +5/ 181 +56 202 +60 203 +59 203 +58 185 +57 181 +57 185 +57 181 +56 225 +54 204 +62 168 +60 170 +60 185 +57 200 +68 246 +31 123 +55 184 +61 170 +61 210 +64 101 +42 178 +63 200 +68 223 +59 200 +68 173 +68 172 +65 170 +67 115 +55 141 +65 114 +57 211 +65 (4) (5) 226 +58 212 +66 200 +69 109 +55 110 +56 110 +56 108 +55 99 +43 THE ASTRONOMICALJOURNAL Gal Neb Spec Sb SO Sb Pec Em E2 Sb Irr E7 E3 Sc Irr Irr Sb Sa Sa SBa F5* Sb F8 E2 Sa Sc El G2* Sb SO Sb SB0 GO E0 G5 Sb Sa E6 G2 Sc Sa E0 G7 Sa GO SBc F5* (6) (7) SB0 G5 Pec Em Sc G3 El G3 SB0 G5 SB0 GO E6 G3 Sb G3 S0p GO* Sc F0" SB0 F0 E4 G3 S0p F5* El GO SO G3 E5 G3 Sa F5* SBb F3" SB0 G2 Sa GO* SO E2 Sb Sa Sb Type A5 G3 F2* G3* G2 Em Em G5 GO G3 F5 F3* G7 G5* Gl* G3* F3" Gl AS" F5* F5* G4* G2 G2* G2 GO* G4 GO G3* Redshlft CorrPits cA>sA RedshlftDlsp + 263 + 1,5681,496la + 1,2771,424 km/sec + 1,2831,118la + 1,506 + 648 + 2,481 - 55 + 371 + 369 + 7,024 + 1,456 + 2,721 + 1,281 + 1,381 + 1,220 + 443 + 1,241 + 5,577 + 1,371 + 1,319 + 1,228 + 1,261 + 1,111 + 1,338 + 688 + 1,039 + 1,333 + 1,460 + 2,8553,011 + 579 + 861 + 781 + 2,8792,753 + 1,116 + 19,150 + 1,449 + 636 + 2,6142,770 + 10,346+10,355 + 1,513 + 547 + 1/491 + 693 + 951 + 1,765 + 1,754 + 1,210 + 2,054 + 705 + 1,354 + 744 + 1,452 + 1,649 + 1,623 (8) °(9)(10) 692 862 718 927 789 + 1,452 + 2,203 + 156 + 423 + 1,363 + 1,201 + 7,008 + 158 + 2,874 + 1,101 + 1,142 + 1,220 + 1,118 + 1,272 + 443 + 1,006 + 1,233 + 5,472 + 1,168 + 1,198 + 1,104 + 1,241 + 1,399 + 649 + 553 + 504 +19,237 + 1,392 + 735 + 1,065 + 1,867 + 1,602 + 1,117 + 2,150 + 588 + 1,745 + 1,198 + 633 + 1,362 + 1,727 1,459 1,233 400 lb 572 595 2a 615 427 730 lb 792 600 720 858 2a 77 2b 2a 2a la 2a 4a la la lb, 1c la 2b la la la la la la lb la la la, lb la, lb la la la la la, lb lb la la la la lb la la la lb la la la la 2a la la la la la la lb la la Error km/sei (ID 150 100 Est 100 200 100 150 100 100 100 50 30 30 50 75 50 20 TOO 65 60 50 65 50 65 80 50 60 40 30 60 30 30 30 40 75 75 20 12 40 75 30 60 50 75 50 65 v 75 40 65 75 75 15 50 50 75 50 75 40 50 ‘ 75 50 One platebyHubble,oneMinkowski. Observed byHubble. Abs. veryshallow,spectrumalmostcontinuous. Observed byMinkowskiaspossibleradiosource. Observed byMinkowski. Abs. linesareweak.ObservedbyMinkowski. Member ofagroup. Em patch1'.8sfbrighteststarwithinlimitsofsyst. Em veryclosetoandnfabove.Possiblememlocalgr. Abs. linesweak,spectrumalmostcontinuous. Abs. Iinesweak,spectrumalmostcontinuous. Abs. linesarenotwelldefined. Observed byHubble. Observed byHubble. One platebyHubble. One platebyHubble. Abs. linesarebroadandweak. Abs. linesareweakandshallow. Abs. linesareveryweak.OneplatebyHubble Abs. linesarebroadandshallow. Observed byHubble. Observed byHubble. Observed byMinkowski. Abs. linesareweak. Observed andmeasuredbySeyfert. Observed byMinkowskiaspossibleradiosource. See note5atendoftable. Observed byHubble. Abs. linesarebroadandshallow. Abs. linesareweakandnotwelldefined. Abs. linesareweak. This andnextonearemembersofUMacld. Member ofUMacld.ObservedbyMinkowski. Observed byHubble. Member ofUMacld. 105 1956AJ. 106 *3481 3675 3684 3665 3686 3681 NGC 3726 *IC 3718 3872 3818 3810 3893 3900 3898 Anon 3923 Anon 3998 3953 3941 3904 Anon 3992 3962 3949 3945 4111 4102 4245 4220 4136 4125 4106 4051 4038 4036 4026 4214 4203 4151 4150 4143 4105 4039 4278 4258 4414 4291 4283 4274 4251 4138 4490 4449 4314 4589 4565 4494 4448 (1) Anon American Astronomical Society •Provided bythe NASA Astrophysics Data System R A (2) 30.7 23.4 22TO 39.4 38.4 24.6 23.9 44.5 43.2 25. 1 44.8 44.7 29.8 46.6 46.6 46. 1 48.5 51.2 50.3 58.9 55.4 52. 1 51. 1 50.7 56.9 55.0 46.7 59.5 59.5 35.5 33.9 30.3 30.5 25.8 24.0 20.0 28.2 25.8 13.7 28.9 17.6 16.5 18. 1 17.8 17.3 15.6 15. 1 13. 1 12.6 3.8 4.5 4.2 4. 1 6.7 5.6 8.0 0.6 8.0 7. 1 7.0 1950 +43 52 + 1730 + 1718 +39° 2' + 179 +47 19 +53 21 + 143 + 1145 +49 0 +27 17 +56 22 - 553 - 334 - 335 - 334 +44 48 +33 29 +30 41 +30 12 +65 27 +43 21 +52 59 +62 10 +52 37 +60 57 +37 16 +47 35 +28 27 +29 53 +48 10 +42 49 +43 57 +51 14 +55 44 +53 39 +48 8 +75 40 +29 35 +29 34 +29 54 +36 36 +39 41 -28 33 -29 2 -29 30 -18 36 +31 30 +30 10 -29 31 -18 37 -13 42 +41 55 +44 22 +28 54 +26 16 + 1140 +26 3 +74 28 + 1140 Dec (3) TABLE 1.REDSHIFTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS Long Lat 206 206 206 243 224 222 129 224 +55 224 +55 224 +55 140° 113 121 260 +32 256 +32 260 +32 256 +43 256 +43 252 +47 256 +32 113 +66 157 +82 105 +60 216 +87 259 +74 207 +87 103 +69 260 +74 102 +69 157 +84 136 +81 114 +72 103 +64 107 +63 179 +78 (4) (5) 160 +84 171 +84 123 +79 119 +76SaA8" 113 +73 111 +72 160 +82 113 +71 107 +65 104 +61 162 +86 159 +84 160 +84 105 +63 113 +67 101 +76 100 +73 136 +85 152 +85 101 +56 136 +76 96 +52 99 +55 92 +42 91 +42 Gal THE ASTRONOMICALJOURNAL +67 +69 +69 +70° +69 +61 +66 +70 +68 +53 Neb Spec Sc Sb Sb Sb SO sop E5 Sc E3 SBb F2" Sc Sc Sb ?" Sc E4 Sa E2 Sa SO SO Gl* El G2* SBb G3 Sc GO SBO G7 E2 Sa E2 Sb Sa SO G2* SBO G5 Sc E6 SO Sb Sc SO SBb G4 SBO G3 E0 El SO G3 SBa GO SBO G3 Sa SBO Sc El Sb Sc SBa G2 Sa Irr El Sb E3 Sc S0 Irr (6) (7) Type A8* F3" G2 F0 G1 G3 G0* FO" G1 G5 G0 F2" G5* F8* A5" G1 A5* G2 Em F8* G2* G5 G3 G3 G5 G3* FO* G3 G8 G5* GO" G2 G7* G5* F5* G5 F5* FO" G2* G2 GO GO G7 G5 Redshift + 1,422 + 1,314 + 688 + 2,002 cAVV + 948 + 1,050 + 1,022 km/ sec + 1,498 + 5,396 + 5,108 + 3,109 + 972 + 1,042 + 5,008 + 972 + 1,702 + 1,038 + 624 + 890 + 244 + 627 + 1,¡09 + 1,059 + 1,794 + 938 + 1,220 + 1,788 + 1,613 + 1,785 + 1,071 + 420 + 979 + 295 + 1,001 + 960 + 1,039 + 445 + 1,305 + 784 + 2,178 + 1,895 + 908 + 1,660 + 1,382 + 878 + 681 + 1,825 + 625 + 715 + 767 + 1,014 + 784 + 7,086 + 1,333 + 693 + 883 + 1,673 + 1,223 + 7,304 + 206 (8) + 1,329 + 721 + 1,221 + 2,011 Redshift + 999 + 1,128 + 929 + 1,318 + 862 km/sec + 5,228 + 4,940 + 1,108 + 4,840 + 3,009 + 1,051 + 1,599 + 984 + 1,551 + 1,666 + 1,134 + 615 + 494 + 882 + 317 + 1,009 + 990 + 830 + 1,092 + 433 + 1,445 + 1,664 + 996 + 679 + 1,506 + 1,205 + 1,022 + 1,337 + 880 + 1,963 + 1,062 + 758 + 998 + 235 + 832 + 1,947 + 1,146 + 744 + 1,376 + 687 + 718 + 1,456 + 1,469 + 956 + 675 + 268 + 1,213 + 7,229 + 7,011 + 2,003 + 1,318 (9) Corr Pits (10) Disp 2a 3 2a 2a la 2a 2a 2b 2a 2a la la la la la la la 1 a 1 a la la la la 1 a 1b 1 a la la la 1b 1 a la la la la la la la la lb, 1c la la Error km/sec (11) 100 150 150 150 100 100 ¡00 100 Est 100 65 60 Bothemandabsareweak. 40 50 ThisandnextonearemembersofUMacld. 65 75 Abslinesareratherbroad. 65 65 40 75 50 50 75 75 50 50 50 65 75 40 65 50 30 50 50 50 50 75 75 40 50 50 50 50 75 75 50 65 75 50 20 65 85 50 50 75 65 65 80 15 8 nf cf3. Abs linesbroad.ThisandnextonemembersUMacld. sp of3.Wildconnectingtriplesystem. Observed byHubble. This andnextonearemembersofUMacld. This andnextthreearemembersofUMacld. Brightest andmiddleof3. This andnextonearemembersofUMacld. X3727 verystrong. This andnextthreearemembersofUMacld. Abs linesweak. Member ofUMacld.Seenote6atendtable. This andnextonearemembersofUMacld. Observed byHubble. Observed byHubble.MemberofUMacld. Abs linesweak.MemberofUMacld. This andnextonearemembersofUMacld. Observed byMinkowskiaspossibleradiosource. Bright empatchatcenter. Forms pairwithabove.OneplatebyMinkowski. np of3.Zwickyconnectedsystem. Abs linessomewhatbroadened. sf 1C3481,connectedwith.Seenote7,endoftable. Spectrum ofbrightcentralpart. 61, No.1237 1956AJ 61 . . . 97H 1956 April © American Astronomical Society 5033 5018 4915 1 4814 4736 5173 5128 5087 5077 5055 5049 5005 1 4826 4631 1 5631 5614 5574 5322 5248 5236 5198 5195 5194 4800 4725 5746 5672 5638 5633 5576 5566 5557 5548 5533 5493 5485 5473 5461 5457 5448 1 5394 1 5377 5364 5371 5363 5353 5308 5273 5253 An on *IC 5812 5713 5689 5687 5668 Anon NGC 5806 5820 Anon Anon (1) 3 8.6+3720 14 58.3-716 3 56.4+3741 2 58.8-416 4 1.0+4925 R ADecLongLatNebSpecc6\ARedshiftDispError (2) (3)(4)(5)(6)(7)(8)(9)(10)(ii) 52.4 48.5 39^ 54.3 +2157 53.3 48.0 54.5 +3242 34.2 30.5 54.3 +4728 39.9 37. 1 35.0 53.7 53.6 53.6 51.4 47.6 45.4 28. 1 27.8 26.3 33.3 30.9 22.0 27.9 22.4 57.5 +25 57.2 +545 37.7 33.7 27.1 25.6 25.0 48.0 +2623 48.0 +2623 42.4 13.6 13.3 11.2 10.3 -1915 18.4 17.8 14.0 17.8 16.9 16.4 15.7 18.5 3.0 5.5 9.8 8.9 1.4 +5435 1.9 +5433 1950 GalTypeRedshiftCorrPitsEst 0 +46 48 +41 24 +25 46 +3249‘ +58 37 +36 51 +47 27 +46 50 +42 18 +56 48 +35 5 + 330 + 328 + 411 +36 43 +35 35 +52 35 + 530 +40 32 +47 31 +31 53 +46 22 +25 22 +55 14 +55 8 + 515 +40 44 +60 26 +61 14 +35 54 + 98 +46 56 -12 24 +54 42 + 440 + 327 -42 46 -16 8 +48 58 - 448 -29 37 -20 21 + 210 -31 23 - 05 TABU I.REDSHIFTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS THE ASTRONOMICALJOURNAL 302 +88 318 +57E4G1 318 +57 295 +83 318 +57 359 +69 306 +51 306 +68 278 +58 327 +49 320 +51 323 +55 320 +55 310 +62 310 +62 283 +49 279 +43 318 +42 324 +52 283 +31 281 +46 283 +29 278 +19 281 +41 85 +71 85 +76 63 +84 88 +59 97° +85° 58 +78 49 +62 65 +56 30 +68 69 +75 62 +79 63 +60 67 +60 38 +72 38 +75 69 +68 69 +69 52 +60 67 +59 68 +59 67 +60 60 +64 59 +66 46 +70 47 +71 69 +68 69 +68 56 +54 62 +56 25 +68 28 +69Sb 77 +55 76 +55 17 +66 +62 +62 E E Sb Sb Sb Sb Sc E4 Sb E0 G5 Pec F8* Sb G7* El Sa E3 Sb E3 Sb El SO SBO GO SBa G5 El Sa El P E0 P Sb SO Sc SO EO Sb SO E3 Sc Sb Sa Sa SO SBO G3 Sc Sc Sb E4 SO Sc Sc Sc SO Sb Sb Sa Sc Irr SO SO Irr , Em F8* G4 G3 GO* GO FO* F5* F5" F8* F8* GI G5 F2‘ G2 F5* G3* G4 GO* Em F8* FO* F8* FO" Em F8 FO" F5* F8" F8* G2 G7 G7 GO G4 G5 G2* G3 G3 G3 G5 G5 G2* G2 GO* G5 G2 G2 G2* G3* G3 G8 G4* + 2,0662,039 + 746 + 591 + 1,7801,771 + 2,3162,457 + 382 + 2,531 + 282 + 1,114 + 1,3011,307 + 3,2693,444 +35,506 +35,596 + 2,2052,354 + 3,7013,797 + 1,6771,662 + 1,9792,144 + 3,8723,969 + 1,5281,509 + 3,1953,297 + 13,418 km/sec +35,084 +35,174 + 1,8701,853 + 2,1192,286 + 1,7161,694 + 2,897 + 3,152 + 1,7891,783 + 1,4551,436 + 4,9304,990 + 1,9702,102 + 3,5583,651 + 1,8321,675 + 2,6472,515 + 500575 + 2,7442,600 + 924987 + 1,013 + 298495 + 247394 + 1,3931,357 + 2,5512,652 + 2,1882,284 + 1,8301,951 + 1,1381,102 + 1,9022,063 3,781 8,733 2,627 2,482 +2,590 2,404 +2,506 2,046 1,976 1,176 1,985 1,022 438 +546 542 +650 468 +261 432 491 Provided bythe NASA Astrophysics Data System + 364 + 1,108 + 611 + 13,448 + 2,660 + 830 + 345 + 2,739 + 1,069 + 3,036 km/sec ■ 2,136 3,877 8,880 2,127 2,565 2,206 1,095 1,140 319 258 2a la 2a 2a la la, lb 2a, lb la la la 1 a la la la la la, lb la la, lb la la 1 a la la la la la, lb 1 a lb lb la, lb la la la 100 100 150 100 100 150 150 100 km/sec 50 65 60 60 60 40 50 65 50 50 50 60 50 75 75 60 50 60 30 75 75 50 50 30 50 30 65 65 65 40 50 65 30 35 65 40 65 40 50 50 50 30 50 50 35 50 40 30 75 75 75 20 8" nofaboveneb. Abs linesarenotwelldefined. Abs linesareweak. Observed byHubble. s poneoffaintpair. Observed byHubble. Abs linesarenarrowandweak. Observed bySeyfert. Observed byHubble. Em linesarebroad,noabs.OneplatebyHubble. Abs linesareshallow. Observed byMinkowskiaspossibleradiosource. Observed byHubble. Em patchinNGC5457.OneplatebySeyfert. One platebyMiller. Abs linesveryweakandnarrow. Brightest empatch1.'3fcenter. Abs linesareveryweakandshallow. Abs linesbroadandshallow. One platebyHubble. One platebyHubble. Observed byHubble. One platebyMinkowski. Observed byHubble. Observed byHubble. One platebyHubble. Observed byHubble. Observed byHubble. Zwicky neb.Cantveryweak.X3727strong. 107 1956AJ. 108 5831 5813 NGC 5046 5838 *1302 *IC 5866 5850 Anon 5857 *1308 5859 5854 5879 5878 5907 5899 5898 5903 5962 5921 5982 5970 5985 6070 16 6027(a) 6015 0) 6181 6027(d) 15 6207 6217 6340 6359 Anon 6627 6574 6482 6478 6384 6643 6674 6661 6658 6703 6702 6822 6814 6710 6824 6921 Anon 6927 Anon 6928 6930 6944 6946 6946 6963 6962 6954 American Astronomical Society •Provided bythe NASA Astrophysics Data System h U 5^7 15 20 R A (2) 34.2 +1646 37.6 +5931 36. 1+1220 38. 6+5930 30.1 +19564+38ScG2+2,1582,3071250Dispersionused1000A/mm. 57. 0+2054 57. 0+2054 50.7 +6228 13.3 +4214 11.0 -145 14.6 +5631 30.0 +76 41.3 +365526+40ScFS"+8691,073la40X3727isverystrong. 34.8 +781878+33ScF8"+1,3861,617lb30ObservedandmeasuredbySeyfert. 15.3 -2355 47.5 +5111 48.2 +453338+38SOG3*+9,3869,608la50Zwickyconnectingtriplesystem.Brighterof3, 31.9 +2250 49.8 +235 15.7 -2351 32.5 +2252 19.5 +515 36.5 t-2520 48.6 45.9 45.5 21.2 +7433 20.4 +1539 42. 1 40.0 42.6 11.1 +722270+33SaG3+2,1092,3511300Dispersionused1000A/mm. 57.7 42.3 29.0 30.2 17.4 +6150 4.0 30.4 4.0 +147329+47E2G2 30.2 26.4 5. 1+5557 2.9 30.6 4.6 +144 34. 1 33.9 5.3 +245 5.2 +1947 35.9 5.3 +1946 44.8 41.6 1.6 44.7 7.4 +050 8.5 +5711 9.6 +1458 1950 +26 46 +45 39 +35 39 +45 30 +55 59 +25 33 +40 35 -14 53 -10 26 + 943 + 942 -14 51 + 945 +59 58 + 941 +59 59 + 020 + 08 + 31 + 649 2 18 1 24 1°54' 1 48 Dec (3) TABLE I.REDSHIFTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS THE ASTRONOMICALJOURNAL 328 +48 327* +48° 329 +48 Long Lot 329 +47 329 +47 354 +57 354 +57 330 +48 309 +27 315 +35 309 +27 354 +49 336 +46 348 +47 340 +34 358 +19 357 -17 353 -20 353 -20 (4) (5) 58 +52 35 +56 59 +51 58 +51 59 +46 59 +47 62 +44 45 +30 58 +34 36+7 42 +19 42 +19 72 +28 22 +13 35 44 56 25 +11 10 +14 16 +22 19 +13 11 +12 19 +12 63 +11 63 22 -18 22 22 -18 22 -18 20 -21 16 -27 18 -24 15 -27 2 +45 2 +45 Gal - 9 +• 5 t-15 HI -19 Neb Spec E3 El E0 SO SO SBb G4* SBa G1 Sb Sb Sb GO Sb E0 Sb E2 G3 Sb E4 G7 SBb F8 Sc GO SBb GO Sb Sc Sc Sa (6) (7) Sc El Sc Sb SBb GO* Sb E2 SO Sb GO* SBb G5 SO Sb Sa SO E3 Sb Sb Irr Irr E7 Sa SO Sa E0 Sc Sc Sb ? Sb El Sb Type G2 G5 G5 GO* G2 G2* F5" F8* G2 G3 G8 GO* F8* F8 G2 G2 G5 F8* G5 GO G2 GO* F0" F8* G5 G7 Em Em G3 Em" GO* G3 GO* G5 Em G3* GO F5 G3 GO* G3 F5* GO Redshift + 1,427 + 1,684 + 1,882 krr\/sec + 1,768 + 2,2782,292la,lb4040"sofNGC5846. + 2,3192,333la + 1,626 + 4,664 + 4,616 + 876 + 2,549 + 2,111 + 2,304 + 553 cAVXç, + 2,467 + 4,415 + 646 + 4,031 + 4,2704,507 + 2,091 + 5,2065,416 + 3,5023,747 + 4,3704,607 + 1,4941,748 + 3,3863,676 + 1,437 + 4,556 + 2,316 + 4,749 + 4,575 + 4,3174,5962a + 16,804+17,098 + 4,277 + 4,419 + 4,754 + 38 + 4,011 + 4,182 + 4,351 + 4,375 + 4,183 (8) 2,612 2,864 2,034 1,993 3,922 6,857 1,389 2,355 2,948 1,784 740 30 34 70 Redshift DispError + 1,696la50 + 1,782la50 + 1,441la50 + 1,890la65ObservedbyHubble. km/sec kir^sec + 2,089 + 2,539 + 3,071 + 1,430 + 2,115 + 4,159 + 2,674 + 2,157 + 4,543 + 860 + 5,025 + 1,590 + 4,857 + 4,811 + 2,592 + 4,659 + 4,994 + 4,517 + 330 + 4,419 + 4,555 + 222 + 4,387 + 4,231 + 4,604 • 4,138 Corr PitsEst (9) (10)(11) 4,695 4,743 2,706 2,068 2,231 1,064 1,644 3,197 7,113 2,559 1,940 924 2a 741 102 98 2a 2a 10a la la la 2a 2a la la la la 2a 2a la 5a 2b la lb la 3a la la, lb 2a la lb la la la lb la la 200 150 150 150 150 125 100 250 50 65 65 40 50 65 75 50 100 40 75 50 50 50 60 50 50 75 50 50 50 10 50 50 65 50 50 40 30 40 30 30 40 20 50 50 75 75 50 40 75 25 Abs linesbroadandshallow. X3727 veryweak. This andnextthreeobservedbyHubble. This and6027(d)membersofSeyfertgroup. Abs linesareweak. Member ofagroup. Obs,measured byMinkowskiasradiosource. Em V,PlateII,Hubble,E.,1925,Ap.J.,62,409. Anon aboveis210sp6927. Dispersion 1000A/mm.Thisandnext3ingroup. In 6822amemberoflocalgroup. Em patch411nfnucleusof6946. Possible memberlocalgroup. Abs linessomewhatbroadandshallow. 61, No.1237 1956AJ 61 . . . 97H 1956 April *1460 6964 (1) (2) Anon 7171 Anon Anon NGC 7217 7177 *IC RA 7242 Anon 7252 7314 7318(b) 7318(a) 7302 7317 7332 7319 7331 7335 7343 7385 7377 7448 7386 7541 7507 7479 7469 23 7457 22 7600 7576 7585 7611 7606 7617 7619 7623 7625 7626 7679 7678 Anon 7727 7716 7741 7785 7743 7742 Anon 7793 WLM 4. Twoveryfaintfieldnebulae.NotmembersofCl0855+0321.FirstoneisNo. 10,secondoneNo.11onchart7. 3. Twoveryfaintfieldnebulae.FirstoneisNo.1,second2onchart No. 2. 7. ZwickybelievesIC3483alsoconnected withthispair.Thediscrepancyinthevelocities,however,indicatesthat3483is amemberofthe 5. Afaintfieldnebula.NotamemberofCl1055+5702.ObjectNo.1onchart No.9. 6. EmissionbandsinNGC4151measured todetermineconstancyofA)/Xfornebularredshifts.Wilson,0.C.1949,Pub.A.S. P. ,61,132. 2. Thepreviouslypublishedvelocityof+2600km/secinMt.W.Contr.531isanerror. 8. Wolf-Lundmark-Melottesystem.Redshift Isthemeanfrom2empatchesnofcenterandclusterpcenter. 1. Averyfaintfieldnebula.NotamemberofCl0025+2223.ObjectNo.9onidentification chartNo.1. American Astronomical Society •Provided bythe NASA Astrophysics Data System Virgo Clandnotphysicallyconnectedwith thispair.SeeTable2forredshiftof3483. 20 h 23 ' 44"fe 58.8 58.5 58.3 59.6 58.3 33.0 33.7 33.7 33.6 29.7 13.2 33.8 13.5 34.8 18.0 35.0 35.0 36.4 58.6 45. 1 57.6 54.5 47.6 47.4 12.2 39.3 37.3 33.9 14.8 41.8 41.4 39.5 16.5 16.3 15.4 5.6 41.8 26.2 26. 1 17. 1 55.9 52.8 17.8 17.6 59.2 18.2 18.0 18.0 0.7 9.4 2.4 1950 + 0°7* + 1556 + 1556 + 167 + 1729 +31 7 -13 31 +37 2 +37 3 -24 56 +33 41 +33 42 -14 23 +33 42 -26 18 +33 43 +34 11 +23 32 +34 9 + 1543 +33 48 + 123 + 836 +29 53 + 425 + 1126 + 1121 + 416 -22 35 -28 49 + 747 - 50 + 753 - 751 - 455 + 756 - 846 Dec + 01 + 87 + 1657 + 756 +22 9 +25 48 + 314 + 1029 - 354 + 538 + 939 -12 34 - 350 (3) -32 51 -15 43 THE ASTRONOMICALJOURNAL Long LatNebSpec 356 355 351 (4) (5)(6)(7) TABLE I.REDSHIFTSOFEXTRAGALACTICNEBULAE.NON-CLUSTEROBJECTS 32 32 32 44 55 330 60 60 15* 61 12 61 62 61 62 56 61 50 50 62 52 56 47 55 65 16 52 43 40 44 57 39 57 57 57 63 57 55 41 56 56 68 55 66 68 67 73 48 4 Gal Typ® -20 El -27° E4 -20 SO -20 Sa -49 Sb -20 SbG7* -30 SbGO* -16 SOGO -58 SOF3* -56 SOG7 -16 E3F8 -21 E2G5 -61 ScF8" -21 SBbG5 -21 E4G5 -21 SbG8* -21 SBbGO" -20 SaG5 -30 SOG3 -41 SOG2 -41 E0G1 -63 S0pG2 -22 E3G2 -49 SOF5* -46 -40 ScG2 -70 E0 -43 SBbG3* -27 -51 Sc -59 SaG2 -59 S0pGO -49 SOG7 -62 ScG2 -62 E5G3 -49 E4G3 -49 E3G5 -49 SOG3 -41 SOGl* -49 ElG3 -54 SO -62 Sc -69 Sa -58 Sb -37 Sc -49 Sb -34 SBcF2 -62 SbF5" -50 SBa -55 E5 -79 ScF5 -74 IrrF5 NOTES TOTABLEI G5 G5 G2 G3 GO F5" G2 F2 G5 F5* F5" G8 G3 G8* GO* GO* G5 Redshift CorrPitsEst + 3,832 + 11,255 + 9,148 cû>/X RedshiftDispError + 1,105 + 2,632 +11,965 km/sec + 5,984 + 911 + 2,586 + 4,733 + 5,684 + 1,766 + 6,638 + 6,736 + 5,638 + 780 + 6,657 + 1,204 + 1,216 + 6,298 + 7,8298,054 + 3,4163,501 + 7,1987,423 + 7,2627,457 + 2,4192,649 + 2,492 + 4,780 + 525 + 1,637 + 2,672 + 3,333 + 3,616 + 3,391 + 3,383 + 2,341 + 3,463 + 4,072 + 3,357 + 3,757 + 2,5462,705 + 3,4463,676 + 1,706 + 6,7776,918 + 1,8391,943 + 5,2025,378 + 1,629 + 729 + 7,016+7,157 + 3,8464,014la (8) (9)(10)(11) 1,802 286 78 + 9,408 + 11,515 + 4,036 + 2,776 +12,225 + 1,192 + 1,360 + 6,272 + 4,815 + 2,716 + 5,972 + 1,838 + 6,916 + 7,014 + 5,916 + 1,058 + 6,935 + 1,492 + 6,576 + 1,464 + 2,711 + 4,988 + 788 + 1,684 + 2,860 + 3,485 + 3,766 + 3,579 + 2,477 + 3,527 + 3,659 + 3,953 + 4,268 + 3,553 + 1,930 + 1,991 1,821 965 292 2a 3 3a,lb20 2a, lb la la la 3a la 3a, lb 2a la la la la la la la la 3a 2a 2a 2a la la la la la km/sec 250 100 100 200 250 250 50 50 50 150 100 30 75 75 200 100 65 150 50 65 50 65 40 50 50 60 20 65 65 65 65 50 40 75 65 60 65 75 65 50 50 75 65 30 60 40 60 40 50 65 65 6! 8spNGC7006. Dispersion 1000A/mm.11.'6npNGC7006. 7! 9sfNGC7006. 3!6 spNGC7242.Maybe7240. Brightest ofsmallgroup,vneb.0.'5nF. p oneofdoubleneb. This andnextthreemembersofagroup, f ofpair. Very poorvalue,redshiftuncertain. Probably memberofgroupnearNGC7318(above). Dispersion used1000A/mm. Dispersion used1000A/mm. Observed andmeasuredbySeyfert.Broadem. Abs linesarepoor. One platebyHubble. This andnextfourmembersofagroup. nf ofpair.5.'8sf1C1505. Abs linesweak. Zwicky connectingpair.ó.'Ssf1C1505. Possible memberlocalgroup.Seenote8. Observed andmeasuredbyHubble. 109 1956AJ 61 . . . 97H 110 *3483 4216 4192 4179 4267 4254 4303 4281 4273 4270 4261 4501 4479 4442 4324 4321 *IC 4492 4486 4478 4477 4474 4473 4472 4461 4459 4458 4438 4435 4425 4421 4394 4350 4339 NGC 4535 4527 4526 4467 4464 4450 4429 4382 4374 4365 4546 4406 4387 1275 4550 4548 Anón Anón 1278 1277 1273 4552 4551 1270 4570 4569 4343 0) © American Astronomical Society VIRGO CLUSTER PERSEUS CLUSTER 3 16.6+4123 3 IsTb+41°18' R A (2) 31.6 31.5 30.6 30. 1 32.9 32.9 31.8 29.5 28.4 27.8 27.4 27.3 27.0 26.5 21.0 20.6 20.4 33.0 28.3 27.9 27.8 27.2 26.8 25.5 25.2 25. 1 24.9 24.7 23.7 23.4 22.9 22.5 21.9 21. 1 33. 1 33.1 27.5 26.5 26.4 25.9 24.5 23.2 21.4 16.5 +4120 16.1 +4122 34.4 34.3 11.3 16.6 +4124 16.8 10.3 19.4 17.8 17.3 17.2 16.3 13.4 17.4 1950 +15 11 + 1442 + 1325 + 135 + 445 + 540 + 537 + 545 + 133 + 66 + 821 + 1240 + 1247 + 1236 + 716 + 531 + 166 + 1137 + 927 + 1351 + 1355 + 1421 + 1342 + 816 + 816 + 826 + 1328 + 1415 + 1331 + 1721 + 105 + 1317 + 1321 + 1123 +13 1 + 13 + 1829 +13 10 + 736 + 1658 + 622 + 1442 + 1544 + 135 + 1828 + 1446 + 828 + 256 + 758 +12 31 + 1230 + 1326 + 1250 - 331 + 731 Dec (3) TABLE II.REDSHIFTSFROMBRIGHTNEBULAEINCLUSTERS 253 +68 242 +74 252 +63 Long Lot 244 +75 238 +75 254 +67 247 +74 256 +75 255 +76 256 +75 243 +80 256 +68 256 +67 245 +77 254 +67 254 +67 255 +78 260 +70 256 +75 255 +76 255 +76 258 +70 258 +70 258 +70 254 +75 254 +76 254 +75 256 +72 253 +75 253 +75SB0G5 255 +72 253 +75 252 +74 243 +80SBbG3 252 +75 251 +75 255 +69 245 +78 255 +69 262 +71 263 +70 260 +74SepGO* 260 +72 249 +79 250 +77 119 118 118 119 118° 260 +77 265 +59 263 +65 264 +70 262 +76 261 261 +75 261 (4) (5) Gal THE ASTRONOMICALJOURNAL -12 -12 -12 -12 -12* +75 +76 E4 El El E3 E7 Irr Neb Spec E7 G5 E3 Sc Sb Sb E0 Sa Sc SB0 G3 Sb SO Sc E0 E0 SO E2 G5 E5 El E2 E3 Sc SO Sc SB0 G3 SO G3 E0 Sap G3 E4 SO E0 Sa Sc E7 E0 E4 E7 SBb G5* SB0 G3* SO SO Sb SB0 G5 SO Sa SBa G3 E3 G7 SO SO E2 SO Sb (6) ■(7) T/pe F8 G3 G2 GO* G3 G4 F8 G2 G3 ?" G2 G4 G2 G5 G3 G5* G5 G7 G3 G5 F5 G1 G3 F5" G7 G3* FO" G7 G3 G5 G7 G3 G5 G3 G7 G7 G5 G5 G3 G3 G5 G5 GO* G3 G2 G5* + 10833 + 1,3171,233 + 1,7351,642 + 1,2901,218 + 6,1156,2452a + 5,160 + 5,354 + 2,1202,060 + 32 + 1,279 + 4,905 + 1,1111,042 + 383309 + 2,485 Redshlft + 2,0481,995 + 580493 + 869 + 1,6921,628 + 714 + 1,278 + 1,617 + 2,202 km/sec cAVX + 1,7301,640 + 1,114 + 772 + 511 + 773 + 954 + 1,171 + 1,184 + 1,714 - 124 - 374452 0 4,974 (8) 2,241 2,602 2,347 1,727 2,302 1,486 1,013 1,887 1,482 1,263 1,526 1,930 1,474 1,199 1,014 1,260 1,883 1,671 447 822 433 350 978 960 276 32 -105 + 918 + 1 + 2,173 + 1,379 + 1,104 + 1,813 + 5,487la + 5,0382a + 1,149 + 5,2932b + 720la + 439la + 1,557 + 2,492 + 2,191 + 2,236 + 1,179 + 2,094 + 2,408 Redshlft Disp + 721lb + 880la km/sec + 1,0694a - 202 5,104 Corr Pits 1,615 1,195 Provided bythe NASA Astrophysics Data System 1,410 1,458 1,843 1,809 1,551 1,027 1,122 1,173 1,605 (9) (10) ,414 357 753 372 882 796 614 896 280 210 908 49 4a, 2b 2a 2a 2a 2a 1 la la, lb la la la la la lb la 1c la lb 1 la la, lb la la la la 300 300 200 250 300 250 100 100 100 150 100 150 100 150 Error km/sec 50 50 40 50 50 40 75 75 75 50 75 65 50 50 50 40 50 50 40 50 50 50 40 20 75 30 50 30 60 50 75 50 50 50 40 40 50 65 50 20 75 65 75 75 65 01) Est 75 Abs linessomewhatwideandshallow. Two platesbyMinkowski. 7:3 npNGC4486. Vel inMt.W.Contr.531isthatofastarprojectedonnucl. Disp 1000A/mm.Obs,measbyS.Smith.4.'8n,3!OpBD+9®2637. Observed byMinkowski.Abslinesveryweak. Disp 1000A/mm.ObservedandmeasuredbySinclairSmith. See note7atendofTable1. Observed byHubble. Disp 1000A/mm.ObservedandmeasuredbySinclairSmith. Disp 1000A/mm.ObservedandmeasuredbySinclairSmith. 2010 spNGC4365. Abs linesareweak. Southern extensionofVirgoCluster. Observed byMinkowski. Pease vel(+1150)inMt.W.Contr.426isanerror. Neb. typeSc+Sb?Wideembands.Radiosource. Disp 1000A/mm.Observed,measuredbySinclairSmith. 61, No.1237 O'! V" 1956AJ. X given inthenotes.Locations ofthefainterob- Their locationwithrespect toknownobjectsis objects havebeendesignated “anonymous.” the followinginformation. 1956 April latter areindicatedbyanasterisk.Uncatalogued *1185 *1194 *1183 *4051 *4045 *4021 *3946 *3900 Tables IandIIarealikeinformcontain Column I.TheNGCandICnumbers. 6041 6045 6044 4908 7499 6047 4898 4896 7503 7501 4895 4889 4860 4698 4881 4874 4872 4869 4867 4865 4864 4850 4742 4660 4886 Anon 4853 4798 4958 13 4941 13 4866 12 4762 4754 4697 4665 4649 4856 4638 4636 4621 4594 4579 4578 NGC *IC 0) © American Astronomical Society • Provided by theNASA Astrophysics Data System h 23 8.1+718 23 7.8+720 VIRGO CLUSTER(Cont'd) PEGASUS IICLUSTER HERCULES CLUSTER COMA CLUSTER 12 58.5+2817 16 12 35TO R A (2) 58.4 +2822 57.9 58.4 +2818 57.9 57.8 57.8 57. ? 57.6 57.5 57.3 41. 1 37.4 35.0 57.2 57.0 56.5 56.2 55.8 53.2 52.5 39.5 42.0 40.3 40.3 56.9 56.8 56.8 56.7 56.4 57.0 46.0 42.6 56.7 50.4 49.8 46.0 49.2 3.5 +1751359 4.4 +1755359 3.3 2.7 2.8 2.6 2.3 7.9 +721 3.2 1.6 1950 + 1752 + 1754 + 181 + 1750 + 1754 +28 13 +28 35 +28 28 +28 19 +28 15 +28 15 +28 31 +28 14 +28 14 +28 11 +28 21 +28 14 +27 32 +27 41 +28 16 +28 15 +28 8 +28 24 +28 5 +27 52 + 257 + 1155 + 125 + 1427 + 1149 - 745 + 1130 + 846 + 320 + 1126 + 1143 - 517 + 1135 -11 21 - 532 -14 46 -10 12 # (3) Dec 950* TABLE II.REDSHIFTSFROMBRIGHTNEBULAEINCLUSTERS 359 359 359 359 359 360 355 275 279 279 285 277 276 273 273 269 264° 272 269 267 268 262 270 270 268 Long Lat THE ASTRONOMICALJOURNAL 53 53 53 (4) (5) 11 11 11 10 15 10 10 14 13 10 10 10 12 13 11 10 9 9 3 8 7 Gal +43 ElG5 +43 SaG3 +43 El +43 EO +43 EO +43 Sb +43 SO +86 ElG5 -48 ElG3 -48 E3G5 -48 E5G5 +86 E2G5 +86 E4G3 +87 SO +87 SO +87 EO +87 E4 +87 SO +87 El +87 E4 +87 SO +87 SO +87 E3 +87 Sa +87 E6 +87 El +87 EO +87 E2 +74 SaG2 +52 E4 +87 El +87 SO +88 SO +88 E3 +54 E7G3 +57 SaF8" +75 SaG3* +47 SBaG5 +74 SBOG4 +71 Sa +57 E5G4 +74 E5G2 +66 SBaG3 +74 E2G7 +74 E6G3 +65 +73 +51 +74 +72° E0 E5 E2 Sb Sb Neb Spec (6) (7) Type G3 GO G5 G2 GO G2 G3 G3 G3 G2 G4 G3 G2 G7 G5 G2 G4 G5 G4 G3 G3 G2 G2 GO G3* G5 G2 G2* G7 G3* G3 GO + 12,714+12,915la50 + 13,229+13,430la65 + 11,916+12,117la50 + 11,642+11,765la65 + 10,452+10,575la200 + 10,038+10,161 + 9,4709,593 + 9,935+10,058 + 9,936+10,059 + 10,469+10,592 + 4,9324,947la150 + 6,5276,542la200 + 8,8388,853la150 + 6,9356,950 + 5,8205,836 + 8,406 + 5,789 + 6,214 + 6,691 + 7,171 + 6,703 + 4,8154,827 + 6,8196,831 + 6,910 + 4,6434,655 + 6,8686,880 + 7,8587,870 + 6,101 + 7,550 + 5,984 + 7,171 + 7,673 Redshift CorrPitsEst km/ sec cAVA- RedshiftDispError ■ 6,416+6,4282a 2,282 (8) (9)(10)(11) 1,251 1,321 1,017 1,389 1,032 1,308 1,080 1,910 1,180 1,752 1,515 1,461 846 868 785 414 973 + 8,4222a + 5,804la + 6,226 + 6,923 + 6,715 + 6,107 + 5,996 + 7,177 + 6,703 + 7,183 + 7,679 + 7,561 + 1 2,201 1,321 1,389 1,398 1,176 1,177 1,011 1,021 1,679 1,862 ,095 729 805 684 955 950 867 339 jects areshownonidentificationcharts,Plates puted fromtheLundObservatory tables(Ohls- nations fortheequinox1950computedfrom NGC. I andII. Columns 4,5.Thegalactic coordinatescom- Columns 2,j.Therightascensionsanddecli- la 50 3a la 75 la 50 la 50 la 50 2a, lb30OneplatebyMinkowski. 2a la la la la 100 la, lb50 la 125 la 65 la, lb40 la 75 1b la 40ThisandnextoneinsouthernextensionofVirgoCluster, la la la la la la lb krn/sec 300 150 150 100 100 150 125 150 50 40 75 75 50 30 50 50 50 50 75 50 50 65 50 30 50 75 75 50 50 75 f oftwobrightest,largestnebnearcentercluster. p oftwobrightest,largestnebnearcentercluster. Very faintmember0:5nf1C3960. Observed byPease. Southern extensionofVirgoCluster. Southern extensionofVirgoCluster. Southern extensionofVirgoCluster. Observed byHubble. Abs linessomewhatwideandshallow Southern extensionofVirgoCluster. 111 O'! V" 1956AJ. X hm type spectrum. son 1932)andbasedonthegalacticpoleR.A. sion patchesinnebulaewere observed.These have beenindicated“Em,” denotinganemission- I240, Dec.+28°(1900). 112 Cluster 0138+1840 1 0106-1536 1 0025+2223 0925+2044 1 0348+0613 1 0855+0321 1 0705+3506 1 2322+1425 8 1534+3749 1309-0105 1+2139.3 1520+2754 1513+0433 1239+1852 1055+5702 2 1024+1039 1 1431+3146 1304+3110 1+1A133.5+319 1253+4422 21253.9+4420 1228+1050 1 Column 7.Spectraltypes, except whereemis- Column 6.Hubble’sestimateofnebulartype. 1153+2341 1 1145+5559 48 © American Astronomical Society • Provided by theNASA Astrophysics Data System 0) 8+9 No. Neb 24 25 1A (2) 2 3 2 2 7 2 7 h0 23 22.0+142463-44 15 34.4+3748 10 24.4+1039 15 20.0+2751 15 13.1+433 14 30.6+3147 12 28.4+1050258+73+50,402+50,3211 10 55.1+572 12 38.7+1851 11 44.5+5559 11 53.3+2341 3 48.2+610 0 2ÍV+2223' 8 55.1+323 7 4.4+358 9 25.7+2045 1 37.9+1840 1 R A (3) 34.8 +3751 30.6 +3149 34.4 +3742 38.8 +1852 53.3 +2341 20.6 +2751 20.6 +2751 20.3 +2755 44.7 +561 44.7 +5558 55.7 +572 55.1 +323 24.9 +2223 20.5 +2753 20.4 +2752 20.3 +2754 20. 2+2752 45.8 +563 22.2 +1424 28.4 +1050 55.3 +322 6.3 -1536 6.3 -1536 5.0 +354 TABLE III.REDSHIFTSFROMFAINTNEBULAEINCLUSTERS 1950 - 14 Dec THE ASTRONOMICALJOURNAL (4) 334 +47 284 +61 Long Lat 264 +81 201 +54 108 -42 197 +78 116 -77 150 -34 116 +55 178 +45 (5) (6) 106 +60 194 +31 150 +20 85° -40° 27 +53 38 +84 83 +73 10 +55 16 +66 Gal +45,557 +45,7161200 +45,706 +45,8651 +22,380 +22,5011 +13,434 +13,647 + 12,514+12,727 +46,114 +46,2731 +22,088 +22,2091 +21,841 +21,962 +20,840 +20,961 +20,775 +20,896 +23,812 +23,933 +20,984 +21,1051 + 19,522+19,6431 +28,300 +28,33316018ClusterinShanecld.A.J.,59,285,1954. +39,496 +39,592 +47,796 +47,9941 Redshift CorrNo.EstIdent +39,046 +39,142 +52,458 +52,3621 +22,056 +22,0141 +51,773 +51,9081 + 16,057+16,0901 +47,479 +47,6772 càX/\ RedshiftPitsErrorChart +21,094 +21,0522 +42,844 +42,796 +23,089 +23,065 +15,440 +15,4731 kn\/sec km/sec +54,887 +54,9171 +59,304 +59,3821 +48,788 +48,7071 +42,819 +42,771 + 15,572+15,666 + 15,459+15,553 + 14,688+14,782 + 14,982+15,076 +41,631 +41,718 +39,914 +40,001 + 19,636+19,489 +57,612 +57,498 +60,959 +60,764 +60,964 +60,7691 +61,241 +61,0461 +23,690 +23,666 +25,662 +25,6441 (7) (8)(9)(10)(11) 1 graph slit. motion withrespecttothe localgroup,obtained sary, correctedforthecurvature ofthespectro- have beenreducedtothesunand,whenneces- pressed ontheconvenientscaleofvelocities.All Column ç.Redshiftscorrected forthesolar Column 8.Measuredredshifts,cAX/Xo,ex- 300 16 200 300 200 12 100 2048-inchSkySurveycluster. 150 100 100 9 100 100 8 150 100 100 11 100 7 100 548-inchSkySurveycluster.Clustermembershipindoubt. 50 50 65 65 75 21 75 65 75 75 75 50 40 50 13 75 50 10 50 60 75 448-inchSkySurveycluster. 60 Largerandnfoneofpair. 60 3ClusterHaufenA.1and2formaclosepair. 60 50 60 50 50 40 X3727appearsinspectrumofNo.8. 75 148-inchSkySurveycluster. 19 CoronaBorealisCluster. 17 15 48-inchSkySurveycluster.Spectra1+1Ablended. 14 48-inchSkySurveycluster.X3727present. 10 UrsaMajorClusterNo.I.Baadenumbers. 9 UrsaMajorClusterNo.2. 8 48-inchSkySurveycluster. 7 HydraCluster. 6 GeminiCluster.No.1isAnon3,2 48-inch SkySurveycluster.No.8isNGC7649. 48-inch SkySurveycluster.Spectrogramqualitypoor. Bootes Cluster.No.IisAnon9inMt.W.Contr.531. 48-inch SkySurveycluster.1and1Aaclosepair. Redshift fromtheblendedspectraof8and9. No. 2isAnon10inMt.W.Contr.531* Leo Cluster.IdentificationonPlateVI11,Mt.W.Contr.426. X3727 appearsinspectrumofNo.2. Anon 4inMt.W.Contr.531. No. 2issfofpair. Smaller, fainter,andnoneofpair. No. 24isAnon7inMt.W.Contr.531. No. 3isAnon6inMt.W.Contr.531. 1 and2formadouble.No.isnpofpair. 61, No.1237 O'! V" 1956AJ. X of declination. of thedeclinationisthenshownandfollowed first twofiguresarethehours,next cluster member,asincolumn2. column i,andtoassignanumbertheobserved The presentpracticeistoidentifyaclusterof values tooccur. by fourfiguresgivingthedegreesandminutes figures theminutes,ofrightascension.Thesign and declinationofthecentercluster.The cause thenebulaearefaintanduncatalogued. details fromthatofTablesIandII,mainlybe- cluster islargeenoughforsomefewnegative No. (7).Cl1431+3146,Nebula1intheBootesCluster. HandKareshiftedtotheregionofX4471.The+m- nebulae bythe1950positionofitscenter,asin No. (5).TheFo-typespectrumofanScnebulawithsmalldispersion. Absorptionlinesarenotnarrowasin(3/Hy- from membersoftheVirgocluster.Theyarenot text. shifts whichisnotaformallycomputedvalue. A/mm ;and“d,”adispersionof70A/mm.About values incolumn8. No. (8).Cl0855+0321,NebulaeNos.1and2intheHydraCluster. ThenarrowspectrumofNebulaNo.1isbelow; No. (6).Cl1520+2754,Nebula5intheCoronaBorealis Cluster.Onlythenarrowspectrumincenteristhat unexpected, astherangeinvelocitywithinthis tive. TheeighthisthenearbynebulaNGC253. which Hubble’slawoftheredshiftsisinopera- spect tothelocalgroupwasmade,thereremained the “a”dispersion. 230 A/mm;“c”indicatesadispersionofno 350 to500A/mm;under“b”thosefrom170 The numberofplatesfromwhichtheredshift seven aremembersofthelocalgroup,within displacements. EightareinTableI,andofthese in TablesIandIItwelvenebulaewithnegative 85 percentoftheobservationsweremadewith order ofthedispersionatX4350,byletter. was derivedisshownbytheArabicnumeral; Formal analysisoftheerrorsisdiscussedin by adding300cos(/—55°)6km/sectothe Included under“a”aredispersionsrangingfrom 1956 AprilTHEASTRONOMICALJOURNAL The arrangementofTableIIIdiffersinsome After thecorrectionforsolarmotionwithre- The fournegativevaluesinTableIIareall Column I.Containsthe1950rightascension Column ii.Theestimatederrorofthered- Column 10.Numberofplatesanddispersion. © American Astronomical Society • Provided by theNASA Astrophysics Data System background spectrumisfromthenightsky. corrected redshiftis+39,046km/sec.Onlythenarrowspectrum atthecenteristhatofnebula.Thefaintwide sky band. the redshiftofNGC1003issmall. emission featureX3727,is+60,964 km/sec. be seenjusttotheredofHe comparisonlineX4471.Thenebulartypeofthisobjectis probably Sb.Nebula as measuredfromtheabsorption featuresHandK,is+61,241km/sec;thatfornumber2,as measuredfromthe the nightsky.Theyappearto redoftheHecomparisonlineX4713.Theuncorrectedredshift ofNebulaNo.1, the narrowspectrumofNo.2isabove.Thestrong,wide isthatofthenightsky,whichalmostblotsout of thenebula.Theuncorrectedredshiftis+20,840km/sec. wideemissionfeaturetotheredofX3889isanight- drogen isstrongandtheemissionfeatureX3727seenat far left.HandKareneartheirnormalposition,as No. I,below,isanelliptical.H andKarenoteasilydiscernibleastheypartiallyfilledin+y thespectrumof the nebularspectra.NebulaNo.2hasabluercolorindexthan 1.Theemissionfeature,X3727,ispresentandcan Notes toPlateIIIcontinued. served individualclusternebula.Whentwofig- as columns2,3,4,5,£,pofTablesIandII. ures areshown,bothobjectswereontheslitand and requiredextendedexposuresonfastblue eral nebulaeinTableIIIarefainterthan19.5 E0-7 8218% TABLE IVB.PERCENTAGEOCCURRENCEOFEMISSION X4350. sion forallplatesisoftheorder370A/mmat tra. Identificationsfortheobjectsareshownin the measuredredshiftisfromtheirblendedspec- troscopic observationsarebecomingmoredifficult plates. Asfainternebulaeareobserved,thespec- Eo —7178G3.7 catalogued objectinthetable.Ithasbeeniden- charts astheexposuretimes,emulsions,andtele- east isatthetop,northright.Estimates chart showninPlatesIandII.Chartshavebeen Plates IandII. of relativebrightnesscannotbemadefromthe tified asNGC7649. scopes areinmanycasesnotthesame. the directionisnorthattop.Forchart20 fying theobjectsobserved.Withoneexception provided astheonlypermanentmeansofidenti- I andII. So+SBb 5248% Sa-j-SBa 3762% Sa+SBa 84G1.4 So+SBo 117G2.2 TABLE IVA.MEANSPECTRALTYPESFORTHEDIFFERENT Type SampleX3727 Type NumberSpec. The apparentphotographicmagnitudesofsev- Nebula No.8inCl2322+1425istheonly Column 2.Thenumberassignedtotheob- Columns 3,4,5,6,7,8.Containthesamedata Column 10.Samedataascolumn11ofTables Column ç.Thenumberofplates.disper- Column ii.Thenumberoftheidentification GROUPS OFNEBULAE Sb-fSBb 102F9.6 Sb+SBb 6680% Sc+SBc 65F6.1 Sc+SBc 4185% Type SampleX3727 Type NumberSpec. All 546G1.4 All 27854% X3727 113 1956AJ 61 . . . 97H © American Astronomical Society •Provided bythe NASAAstrophysics Data System Plate I.IdentificationChartsfor FaintNebulae O'! V" 1956AJ. X © American Astronomical Society •Provided bythe NASAAstrophysics Data System Plate II.IdentificationCharts for FaintNebulae "A O'! V" 1956AJ. X a veryfaintnebula. and time-consuming.Interferencefromthenight- intensity onmoreextendedexposureswouldal- sky spectrumisalreadyseriouslylarge;itsgreater most completelyobliteratetheweakspectrumof displacements sofarmeasuredmovetheHand length limitoffastblueemulsions,andnecessi- be thegreaterredshiftsoffaintnebulae.Largest 114 THEASTRONOMICALJOURNAL61,No.1237 ments willmovethembeyondthelongwave- K linestotheregionofÀ4700.Greaterdisplace- nebulae withrelativelybluecolorindices,the promising methodofobtaininglargerredshiftsis tate useoftheslowerpanchromaticemulsions. vantageous forseveralreasons:(1)identification identification ofsuchobjectsinfaintclustershas this featureappearsfrequentlyinthespectraof the observationofemissionlineX3727.While absorption feature;(2)thenight-skyspectrum however, observationofanemissionlineisad- The othertwowereforegroundnebulaeandcon- candidate forclustermembership.Although comparison ofblueandyellowdirectphoto- proved uncertain.WithinthelimitsofHydra is considerablysmaller.Theseadvantagesare shorter exposure;(4)theerrorofmeasurement emission featurewillregisteronarelatively it standabovethebackgroundspectrum;(3)an of anemissionlineismorepositivethanfor siderably lessdistant.Inspiteofthisuncertainty, one ofthethreewasamembercluster. the wave-lengthdisplacementshowedthatonly graphs. Eachofthesewastestedasapossible Cluster threesuchobjectswerefoundfrominter- builds upanemissionfeatureandtendstomake where ablueandrednebulawereobserved X3727 wasobservedinthespectrumofallthree, simultaneously. EmissionX3727showsinthespec- bers oftheHydraCluster(PlateIII,No.8) illustrated inthespectrumoftwofaintmem- trum ofthebluenebulawhileabsorptionHand redshift forbothobjectsisthesame. A firstattempttoobtainareadablespectrum fainter nebulaeiscostlyinthematteroftele- K ispresentinthespectrumofred.The from amemberoffaintclusterhas,infact, tions inone,orpossiblytwo,veryfaintclusters. scope time,thepresentplanistomakeobserva- cate that,atthe200-inch, exposuretimesfora been made.Althoughnotsuccessful,itdidindi- of theorder50hoursor more. nebula ofapparentmagnitude about20.5willbe Also contributingtowardlongerexposureswill What seemsatthepresenttimetobemost Although thespectroscopicobservationofstill © American Astronomical Society • Provided by theNASA Astrophysics Data System o decision toundertakesuchworkresulteddirectly brighter extragalacticnebulae,wasinitiated.The trograph fortheCrossleyreflectorin1935,a from advancesmadeatMountWilson(Hubble program ofspectroscopicwork,mainlyonthe virgin territoryforspectroscopy.Thepresent various spectralfeatures. extensive notesdescribinginmoredetailthe section givestheprincipalLickobservational results intheformofatableredshifts,with The originallistofnearly200objectscomprised help intheselectionofnebulaetobeobserved. correlated withtheworkatMountWilson,where were asfollows: Hubble gaveinvaluableadvice,guidance,and 1929; HubbleandHumason1931; 1931) inthisfield,whichatthattimewasalmost brightest, resolvedstars:116spirals. lae: 35withMg<11.6and8>—30; observation: 47nebulaewith8>+64°; spectroscopically, northofthe100-inchlimit the Shapley-Amescatalogue,thirdfromthen three groups.Thefirsttwowereassembledfrom unpublished materialbyHubble.Thesegroups made estimatesofapparentmagnitudesthe vided byHubble.Hehadconcluded,frommore war, workwasresumedinNovember,1945,ona served. During1935to1950,however,there of resolvedspiralswasreducedto66.By1950 resolution forindividualstars,andthenumber spirals ontheoriginallistarebeyonditslimitof and better100-inchplates,thatmanyofthe revised andshortergroupIIIlistkindlypro- and formanyofthoseingroupIII.Afterthe occurred newdevelopmentsandintereststhat the 148nebulaeonthreelistshadbeenob- tained forallofthe82nebulaeingroupsIandII, are reflectedinthepresenttwofoldgreaterlist of 300redshifts(TableV).Examplesextra- Galaxy andthenearergiantspiralsM51,81, sible newmembersinthegroupsaround program observationsareredshiftsfor:(1)pos- groups andclusters;(3)nebulae ofintermediate P and M101;(2)brighternebulaeinthenearer troscopic rotationandmeasurement ofinclined brightness observedprimarily forsenseofspec- Program. Uponcompletionofanebularspec- The initialCrossleyobservinglistswereclosely Group I:allcataloguednebulae,unobserved Group III:nebulaeforwhichHubblehad Group II:previouslyunobservedbrightnebu- By March,1942,spectrogramshadbeenob- PART II.LICKLISTOFREDSHIFTS O'! V" 1956AJ. X © American Astronomical Society •Provided bythe NASAAstrophysics Data System No. ObjectType is He+H. No. (3).InthespectrumofIC 342thehydrogenlinesHßandHyarebright.Otherabsorption featuresarenarrow No. (1).AbsorptionlinesinthespectrumofNGC221arewide butwelldefined.Thespectraofmostellipticalnebulae son spectrumisFe.Alloftheothersaregratingspectraobtained withthe200-inchtelescope.Thecomparisonspectrum No. (2).InNGC224theabsorptionfeaturesarenotwelldefined, andareapproximatelytwiceaswidethoseinthe No. (4).Smalldispersionspectrum ofanellipticalnebula.Onalargerscalethisspectrum would belikethatof(1). 4 NGC4365E2G5 3 IC342ScFo 2 NGC224SbG5 1 NGC221E2G3 Notes. Numbers1and2areprismspectraobtainedwiththe100-inch telescope.ThedispersionisatHy;thecompari- spectrum ofNGC221.Thesecharacteristics appearinthespectraofmanySbnebulae. are verysimilarincharacter. and sharp.SpectraofmanySc nebulae arelikethatofIC342. Neb. Spect. Plate III.MountWilson-PalomarSpectraofExtragalacticNebulae 370 A/mm55 m 185 A/mm45 70 A/mm505 70 A/mm1320 Disp. Time Orig. Exp. Observational Continued onpagenj. No. ObjectType Data andNotes 6 Cl1520+2754E 5 NGC1003Sc 8 Cl0855+0321,No.i 7 Cl1431+3146E Cl 0855+0321,No.2 Neb. Spect. Orig.Exp. Type Disp.Time G3: 370A/mm168 G3: 370A/mm60 Fo 370A/mm55™ 370 A/mm380 O'! V" 1956AJ. X o i clusters, and(3)spectralcharacteristicssuchas periods, masses,anddirectionofrotation,(2) of nebulae,preliminaryresults havebeenpub- energy distribution,occurrenceofemissionradia- redshifts forestimatesofrelativedistancesand among nebulaeofdifferentclasses.Foranumber of stellarcontent,particularlytherelative of velocitydispersionsmultiples,groups,and lished, orthespectroscopic datacommunicated and IIindifferentpartsofthesamenebula abundance ofBaade’sstellarpopulationTypesI inch (Sandage1954a). category (3)maybecomeusefulforbroadstudies useful forotherpurposes.Amongtheseare: number ofintermediate-andlate-typespiralsare ments, thespectrogramsofrelativelylarge realization that,formanyofthenearerspirals galactic motion,thesituationisalsochanged, nebular spectroscopicprogramhavetosomeex- beyond thelocalgroup,resolutionintobrightest, but foradifferentreason.Thisistherecent tions, andvisibilityofabsorptionlines.Datain tent becomesupersededbytheserecentdevelop- non-variable starsisdifficultevenwiththe200- developments indicatethatstudyofthelumi- ties, becauseofobservationalselection.Forthe form forthebrighterandintermediateluminosi- nitudes maybeusefulmainlyfordeterminingits motion oftheGalaxy(Hubble1939). luminosity functionofnebulae(Hubble1936b, to otherswhorequested them forspecialpur- nosity functionbymeansofredshiftsandmag- tives havechangedconsiderably.Morerecent included someofthefirstLickredshifts,for based mainlyonMountWilsonmaterial,ofthe all thebrighternebulaehaving8>—30and of residualsintheredshift-magnituderelationfor program, Hubblepublishedadetaileddiscussion, solved stars.DuringtheearlieststageofLick were tobeestimated,forremovaloftheredshift Mg <12.1.Thesecondwasasolutionforthe on Crossleyor20-inchastrographplates. sion amongthenearernebulaewhosedistances motion oftheGalaxyandvelocitydisper- tigation oftheluminosityfunctiononbasis the cooperativeprogram.Thefirstwasaninves- galactic latitudes,orofpeculiarcharacternoted (1) spectrographicrotations,forestimatesof term, fromapparentmagnitudesofbrightestre- 936c) aswellapreliminarysolution,which 1956 AprilTHEASTRONOMICALJOURNAL115 interest, suchasthoseofuncertainnatureinlow spectrum lines;(4)objectsofspecialorunusual P Although theoriginalobjectivesofLick Since 1939ideasconcerningthosetwoobjec- There wereoriginallytwomainobjectivesof © American Astronomical Society • Provided by theNASA Astrophysics Data System , given theproperlengthandorientationinposi- lines. consideration. Thefirstrequirementisadirect some condensationjudgedlikelytoshowemission racy. Wheneverpossible,therefore,theslitwas tion angletoincludeboththenuclearregionand see and,ifmeasured,yieldresultsoflowaccu- often haveabsorptionlinesthataredifficultto spectra oflate-typespirals,becausethelatter emission patches.Suchobjectsareparticularly condensations, whichinmanycasesprovedtobe finding faintobjects. reference starthatcanbeseen inthefieldon photograph showingthefaintobjectwhosespec- slit onaveryfaintorinvisibleobjectdeserves useful forthemeasurementofredshiftsin slit, anditspositionwith respecttothefaint trum isdesired.Next,there isselectedanearby in TableVtheslitwasplacedonfaintorinvisible holders, exposingthecomparisonspectrum,or locating anoff-axisguidestar,changingplate keeping theslitinfocusofmainmirror, various positionangles,lessriskofdisturbance prime focusinsuchroutineactionsasadjusting damage tothespectrographbyobserving during longexposures,andreducedpossibilityof of 6';(3)mechanicalandoperatingconditions, conveniently coveredbythemaximumslitlength eters fromabouti'to15',whichisarange advantageous becauseof:(1)opticalefficiency, result ofexperienceacquiredduring20years.In the slitforwidth,lengthandpositionangle, as theresultofoperatingspectrographat platform. Nodifficultieshavebeenexperienced cally thanhorizontally,easeofsettingtheslitin such asfewerdifficultiesfromflexureinasup- and innerspiralstructure—haveapparentdiam- nebulae whosebrightestparts—nuclearregion background; (2)convenientscaleof38i6/mm scattering, distortimages,andbrightenthesky mirrors thatmayloselightbyreflectionand resulting fromabsenceofoneormoreauxiliary of the36-inch//5.8Crossleyreflectorhasbeen been described,therearesomegeneralremarks operation andlaterimprovement(Mayall1935; poses; referencestosuchcasesarecontainedin porting structurethatworksmorenearlyverti- the NotesaccompanyingTableV. that issuitableforbrightandmedium-bright the firstplace,itslocationatprimaryfocus that maybemadeaboutitsperformanceasthe Mayall andWyse1941)ofthisinstrumenthave Observing Technique.Foranumberofnebulae In thisconnection,theoperationofplacing Spectrograph. Althoughdetailsoftheinitial O'! V" 1956AJ. X detect, duringlongexposures,displacementsdue larly beenusedwiththeCrossleynebularspec- gular orpolarcoordinatesmaybeused,butin object isdetermined.Inprinciple,eitherrectan- between objectandguidestar,whichmaybe trograph. Thereasonisthatithasbeeneasierto practice positionangleanddistancehaveregu- 116 guide stariskeptfixedonthecrosswireinter- to differentialrefractionandinstrumentalflexure, more thanadegreeoff-axis.Thus,evenifthe globular starclusters,brighteststars,ornovae, reference star,thelatterbecomesvisible.When oriented onthelinejoiningobjectandnearby and possiblyoutof,theslit.Butifslitis section, theobjectsometimesmovestoedge, coming throughtheslit.Bythismeans,viewing except forthenarrowlineofnight-skylight very faintobjectappearsinafieldthatisdark This isprovisionforviewingtheslitfrombehind setting theslitonimagesofthresholdvisibility. concluded thatmaximumvisibilityoccurswhen very faintobjectsinthefieldofareflector.He of theguidestar. crosswire intersectionre-adjusteduntilitcoin- optical conditionsthatdeterminethevisibilityof components, suchasstarclouds,emissionpatches, cides withthebrightapexofcomaticimage again centeredintheslit,andpositionof many yearsagobyH.D.Curtis(1903)and conditions approachthoseinexperimentsmade with apowerofapproximately1000X,whichis the fieldisviewedwithamagnificationof30X magnitude. Bowen(1947)hasinvestigatedthe all ofwhichusuallyarefainterthanthe15th this relativemotionoccurs,thereferencestaris jaws andpassagethroughalargercollimating iting visualmagnitudeforstars.Moreover,the nearly Bowen’sfigurefortheCrossley.Thusa mental featurethathasprovedinvaluablein from thefrontinvolvesreflectionslit consists onlyofasmallcollimatinglensandtotal optical systemforviewingtheslitfrombehind H. N.Russell(1917),whoinvestigatedthelim- nebular spectrographincorporatesaninstru- to meetingthisopticalcondition,theCrossley for eachinchoftelescopeaperture.Inaddition nearer spirals,slitspectrogramsofthebrighter ing veryfaintobjectsbecomesall-importantifa lens andthreetotal-reflectionprisms;forboth systems thereisacommon viewingtelescopeat reflection prism,whereasthatforviewingtheslit moderate-sized telescopeisusedtoobtain,inthe the sideoftube.Under theseconditions,and with allair-glasssurfacescoated withnon-reflect- Visibility ofFaintObjects.Theproblemsee- © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL Objects intherangefrom15to17Jphotographic cases, theslitusuallyhasbeensetonthemby color indices,starsof17Jto18photographic can beseenbehindtheslitthaninfront.The magnitude maybeseen,butforsafetyinsuch limiting visualmagnitudeisabout17,forgood aluminized, objectsnearlyonemagnitudefainter with anoff-axisguidestar. magnitude generallywerecenteredandkeptin the useofareferencestarandpolarcoordinates. seeing andtransparency;dependingontheir ing filmsandthecurved,polishedstelliteslitjaws was notfoundpossible,however,torelateinany expected toshowconsiderablevariation,and compositeness (PlateIV),thenormalorunshifted Toepfer SerialNo.445,havingascrewof0.5mm were measuredbymakingmicrometer-wireset- slit viewingsystem,incombination,ofcourse, systematic correctionsdeterminedfromresiduals features byapplyingtotheinitialvaluesaverage lengths wasdeducedforemissionandabsorption as nebulartype.Instead,asystemofmeanwave same featurewithsomeothercharacteristic,such systematic waydifferentwavelengthsofthe differences amountingtoseveralangstroms.It wave lengthsofthespectralfeaturesmaybe Since thespectraofspiralsshowahighdegree cessive approximation,withstartingvaluesob- the slitonlybyintermittentuseofrearward plate. TheresultsaregiveninTableVI,where there isevidenceinthemeasurementsforreal in thenebularspectraweredeterminedbysuc- persion tablewascomputedintheusualwayby pitch. Whensufficientplateshadbeenmeasured tings onspectrumlines,withameasuringengine, spectral features,generallyshortwardof3900; the seconddecimalhaslittlesignificancebeyond tained fromlaboratory,solar,orstellarsources. screw, averageswereformedandastandarddis- to indicatetherangeinsettingsoncomparison able inintensitythattheiraveragewavelengths in km/secfromthepreliminarymeansforeach the Hartmannformula.Wavelengthsforlines lines forafiducialpositionoftheplateon feature (Mayall1939;Humason 1947),butfor minations. are toouncertainforconsistentredshiftdeter- these areblendswhosecomponentssovari- lengths foundforsomeinfrequently-measured that ofaguardfigure.Thistableomitsthewave 3727 of[011]generallywas thepredominating in thevicinityofG-band andHb;inemission, tures weretheHandKlinesofCa11,blends Measurement oftheSpectrograms.Allplates The mostfrequently-measuredabsorptionfea- 61, No.1237 O'! V" 1956AJ. X andn6 s of hydrogenin205and3034. lines duetoPd,Pb,SnandCd, with theshortest(left)andlongest(right)wavelengthsof3460 Pdand5085Cd.Inthe linear dispersionis430A/mmat Hy,withslitlengthsrangingfromi'to6'.Thecomparison spectrum consistsofspark [0 in].TheHandKabsorption linesofCa11areconspicuousinNGC1888-9(h)i449( > upperspectrum),those nebular spectrathemostprominent shortwardemissionis3727[O11],whilethelongwardones areHß,4958and5006 © American Astronomical Society •Provided bythe NASAAstrophysics Data System ! Plate IV.RepresentativeSpectraofExtragalacticNebulae.Enlarged 8.8Xfromtheoriginalnegativesonwhich Mlllll' ïîîl ' !Illl~ií ill! Mill'll! Ml ill IMINIM< ■ II:¡1!tMl III! I Ml! !I (d) 1068 (a) Baade'sV (c) 864 (b) 205 (g) 1518 (6) 1187 (h) 1888-9 ¡ ; , > MHUI= (Ml|<*iIt ni« is.!MI-Ni»I hii nfl ni iHI i illMlUIII I I!II1t!' i -111■nmis11 »III ¡¡IIIII Mil IIIII (k) Hoi (I) 2I3'9 in) 3395-6 (m) 3034 (I) 2835 (o) 3432 \^m I • I ... S' ; ! HI'i8ts11 ¡Hit IttillRI#941 : 111! I!Ml11II ir mini! HI !«fSI’» II t'shiIMIt1 (r) 4214 (p) 3512 (s) 4647,9 (q) 3938 (w) 6217 (u) 5713(SI) (v) 5713(^O) I ' -xMaHHHr' I :Mil 11 mi i II I It! O'! V" 1956AJ. X generally byfactorsof2or3,thanthediffer- vidual lineswerecomputedforsomeoftheearlier The rangeisfrom2to234km/sec,andthemean with single-plateprobableerrorsevidentlymuch ences betweenthemeansforduplicateplatesof was measured,itassignedaweight,ranging realistic indicationoftheaccuracytabu- a normalerrorfunction.Instead,averagedevia- weights, aregivenforeachplateinTableV.In ing, anddispersion,insofarastheymightaffect ance forsuchfactorsasintensity,width,blend- from Jto3,whichwasintendedincludeallow- ever possible.Atthetimeeachspectralfeature 1956 AprilTHEASTRONOMICALJOURNAL velocity standards;but,percentagewisefornebu- lated redshifts.ThesevaluesofA.D.incolumn on theassumptionthattheymaygiveamore tions (A.D.)havebeencomputedforeachplate, inappropriate touseaprecisionindexthatim- smaller thanobscuresystematicerrors,andob- plates, theirvalueswereconsiderablysmaller, measured, theiridentificationisgiveninthe the emissionpatchesbrighthydrogenlines, but thefewnearestnebulae,particularlythosein lar redshifts,theaccuracyissatisfactoryforall internal precisionisnothighbystellarradial- plies numerousresidualsdistributedaccordingto tainable fromonlyafewlinesperplate,itseems the samenebula.Underthesecircumstances, probable errorsofthemeanredshiftfromindi- number oflinesmeasured,andthesumtheir the reliabilityofmeasuredredshift.The 72 km/sec;for99percentoftheplatesA.D. Notes tothetable. those caseswhereonlyoneortwolineswere son 1954)hasrecentlybeen completedtoprovide the localgroup.Forthem,higherdispersion,or such dataofrelativelyhigh accuracy. servations aredesirable,andaprogram(Huma- more extensivelow-dispersionspectrographicob- than 1Ó0km/sec.Thesefiguresshowthatthe is lessthan200km/sec,andfor81percent, \JSfe m]widepairat3967and3868,the [0 in]linesnearHßwerealsomeasuredwhen- (11) ofTableVaredistributedasfollows: IOI-I20 28 Accuracy oftheMeasurements.Althoughformal (km/sec) No. Although theforegoingdiscussion isintended 41- 6080 6l- 808l 21- 408l 81-IOO 58 A.D. © American Astronomical Society • Provided by theNASA Astrophysics Data System O- 2032 22I-24O 2 201-220 2 I61-180 II I81-2OO 2 141-160 10 I2I-I4O 22 (km/sec) No. A.D. Total 405 These, ofcourse,arebestinvestigatedbycom- redshifts inTableV,itleavesunansweredthe question oftheexternalorsystematicerrors. to givesomeideaoftheinternalaccuracy on thebasisofmorethan100nebulaeobserved redshifts inTablesIandIIprovidestheneces- parison ofindependentsetsobservations.The sary materialtoexaminethesystematicerrors, after TableV. emission radiationsinvaryingintensityfordiffer- Hamilton, andthedetailedcomparisonisgiven Mount Wilson-Palomartwo-foldgreaterlistof ent objectsandfordifferentregionsofthesame classes ScandSBc.Theirspectrafrequentlyshow the originalCrossleyprogramthatincludeda in commonatMountWilsonand easy toseeothersverydifficultdetect,and object, absorptionfeaturesrangingfromsome normal andbarredspirals,thoseinHubble’s colors measuredphotoelectricallybyStebbins shadowed bypreviouswork,especiallyfrom more theimpressionofdiversitythanuni- continua suggestiveofmoderatelyearlytolate tains arelativelyhighpercentageoflate-type large numberofresolvedspirals,TableVcon- case (MountWilson),andinafewminutesof focus ofthe100-inchwherescaleiseight spectral types(Humason1936,Fig.1)andfrom istics oflate-typespiralshasalreadybeenfore- formity. Thiswiderangeinspectralcharacter- lengths measuredinafewsecondsofarcone scopic observationsrepresentcoveragebyslit and Whitford(1937,1952).Manyofthesespec- spectral type.Thatistosay,thespectragive A strikingexampleofthiseffectisthatalready same nebulamaybeappreciablydifferent,since times greaterthanthatoftheprimefocus tained formanyofthenebulaeatCassegrain areas located,ingeneral,aroundthebrighter tral typesandcolors,however,refertosmall regions andtolargerportionsofthemainbodies. circumstances, estimatesofspectraltypeforthe Crossley. Asaresult,thetwoseriesofspectro- the MountWilsonspectrograms,whichwereob- nuclear regions.Thiswasespeciallythecasefor estimated spectraltypesofA7forthe10"diam- they wouldreferrespectivelytosmallnuclear arc intheother(Lick).Underthesedifferent eter nucleus,andGofortheinnermost,surround- reported forM33(MayallandAller1942),with leading, togiveestimates of spectraltypes,be- of spiralsitwouldbedifficult, orpossiblymis- many oftheCrossleyspectra ofprincipalparts ing spiralstructureof6'diameter.Moreover,for Spectral Characteristics.Forreasonsrelatedto 117 O'! V" 1956AJ. X compositeness inspectralcharacteristics—nocol- frequent occurrenceofemissionradiationsin with newones,todosowouldrequireanamount show abnormalfeatures,suchasbarelyvisible, in theNotesforthosenebulaewhosespectra spectrum oftenindicatedifferenttypes,whilethe of observingtimedisproportionatewithrespect satisfying toreplacenearlyalltheolderplates quality wasveryworthwhileasshowninPlate re-observed inthiswaytheimprovementplate exposure andanarrowerslit.Formostobjects grainy thanthoseobtainedafter1945,whenthe general remarksthatmaybemadeaboutthe of theextremesabsorption-andemission-line of fairlytypicalspectraspirals,aswellsome unusually broad,orexceptionallystrongabsorp- fusion. Forthesetworeasons—variationand patches orthroughoutthespiraladdstocon- cause differentabsorptionfeaturesinthesame slit, sothatcorrectionofthemeasurementsfor emulsion cameintoregularuse.Foranumberof measurements ofspectrum-lineinclinationswith cludes redshiftsfrom25straight-slitplates,for to expectednewresults. nebulae theearlierplateswerereplaced,orsup- remarkably fastandfine-grainedEastmanIIa-0 the observationalresultsobtainedfromCross- intensities andwidths. Instead, somesupplementaryinformationisgiven which thereare13correspondingcurved-slit prismatic curvatureisnecessary.TableVin- plemented, withlateronestakenshorter before 1942areingeneralweakerandmore in qualitytothelaterones.Thus,platestaken the earlyobservationsareconsiderablyinferior basic material.Asinmanyextendedprograms, and morecompleteinformationregardingthe reported inpreliminaryform(Mayall1948a) the senseofspectrographicrotation,previously ley spectrograms.Omitteddataarethedetailed tion oremissionlines.PlateIVshowsanumber umn ofspectraltypesisincludedinTableV. minus straight,is+36km/sec,witharangefrom the earliestplateswereobtainedwithastraight IVu andv,NGC5713.Althoughitwouldbe Notes forTableV,givenbelow,thereareafew tion ;thesedatawillbegiveninlaterpapers. distribution andoccurrenceofemissionradia- plates. Theaveragesystematicdifference,curved is thusnotaccuratelydetermined, acorrection 118 — 115to+186km/sec.Although themeanvalue Finally, thefactshouldbenotedthatsomeof In additiontothecolumndescriptionsand Table ofRedshifts.Vcontainsnearlyall © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL of +36km/sectothestraight-slitresultsfor emission patches;thesamefigureunderlined dagger (f)whenitislocalizedinoneormore out thenuclearregionormainbody,andbya emission appearstobegenerallypresentthrough- greater dispersion(TableI).Accordingly,the strength, thisfactisindicatedonthefigurefor regarding theorientationofslitisgivenin while thesamesymbolwithpositionangle observed redshiftsinTableVobtainedfrom ment withthecurved-slitresults,and when twoormoreplateswereusedtoobtaina means thelinesarerotationallyinclined. the numberoflinesbyanasterisk(*)when in anumberofcases,supplementaryinformation denotes earlyplatesobtainedwithastraightslit, km/sec. straight-slit plateshavebeencorrectedby+36 tion ;when3727[011]waspresentinmeasurable their totalassignedweight,andaveragedevia- the Notes. angle ;anasterisk(*)withtheslit-lengthfigure level ofintensities. as follows: Mount Wilsonresultsbasedonmorespectraof M 31and32appreciablyimprovestheagree- same nebula;inbothcases, parenthesessig- in column(10),and(b)forindividualcondensa- mean redshiftforcolumn(13)withtheweights man spectroscopicemulsionsfortheastronomical Ultra Rapid;andla-O,i03a-0,IIa-0=East- Soft, generallyHandD850,butwithafew shift, whenseveralobjectsweremeasuredinthe tions referredtothemeanornuclear-regionred- emulsion; forthelatter,IES=ImperialEclipse given intheNotes,withchartsPlateVfor otherwise, amoredetaileddescriptionorlocation nify thattheresultswerenot usedforthedeter- indicates thattheslitwasalongmajoraxis; brackets []arebySandage. published, laterrevisionsbyHubble;thosein from thoseinPettit’spaper,theyrepresentun- few faintestnebulae. magnitudes andcolors;wherethesetypesdiffer as quotedinPettit’s(1954)listofphotoelectric 1200; Ilf=Ilford;AgfAgfaSpectralBlau Detailed dataforthecolumnsofTableVare Columns p,jo,jj.Numberoflinesmeasured, Column 12.Residualsfor(a)individualplates, Columns 6,7,8,Slitwidth,length,andposition Column I.NGCorICnumber,whenavailable; Column 2.NebulartypeassignedbyHubble, Columns j,4,5.Date,exposuretime,and 61, No.1237 O'! V" 1956AJ. X © American Astronomical Society •Provided bythe NASAAstrophysics Data System h Plate V.Identificationchartsof nebulaeandemissionpatchesforwhichthedescriptionsmaybe insufficientintheNotes hm, (a) O23"’I4!4,+40°40'7(’50) (c) (b) 0268,+39°12^1(’50) / to TableV.Foreachchartnorth isup,eastleft,andthefieldsizeapproximatelyI3'Xi6 . Baade’s"a"and"b” (Note I) (Note I) (Note 2) * Il / • (t. t* ' #■ * v * ♦ "a“ I (d) NGC3109 (e) Shane-WirtanenCloud ;Al|;, - 2 ■ ai/ (Notes 81and82) ■^4^ •; ; t * I 3 ‘ 1956AJ. 1956 April NGC Anon Anon Anon Anon [Sa] Anon [Irr] (M31) *IC (M32) (1) 134 185 Ep 205 SBo 214 210 718 672 SBc 613 Sb 604 428 289 [SBc] 278 255 221 753 *79 [El] 224 578 520 514 871 864 877 925 908 American Astronomical Society •Provided bythe NASA Astrophysics Data System Neb. Type Gas. Neb. [El] [E2] [Sc] [Sb] Irr (2) E2 Sb Sc Sb Sc Sb Sa Sc Sc Sc Sc Sc Sc Sb Sc Sc 52 Aug26.4 46 Sept21.3 52 Aug18.4 41 Sept23.4 46 Sept23.3 51 Oct22.2 36 Sept26.5 41 Sept18.4 51 Sept27.4 51 Sept7.4 48 Aug30.3 35 Sept24.5 41 Nov15.38.0Ilf 49 Dec22.2 36 Nov13.2 36 Sept25.4 35 Nov25.2 48 Sept11.4 35 Nov27.2 35 Nov25.2 36 Sept4.4 49 Dec12.76.0HaO 47 Nov9.3 36 Nov19.1 36 Nov19.1 35 Nov27.2 35 Oct4.2 35 Sept23.5 41 Oct23.4 49 Nov18.2 49 Nov25.2 36 Dec9.2 37 Aug12.4 36 Aug24.6 37 Nov25.3 37 Oct10.4 35 Nov30.2 37 Dec1.3 51 Sept25.3 51 Nov3.2 53 Oct11.4 51 Dec23.1 51 Dec22.2 51 Oct22.3 51 Nov4.3 52 Dec15.22.0HaO 49 Jan31.2 36 Dec17.3 52 Dec18.3 36 Nov20.3 53 Nov8.4 53 Nov29.3 Mean UT Date (3) THE ASTRONOMICALJOURNAL Exp. Hr. (4) 6.7 3.5 6.0 8.0 8.0 7.0 3.0 4.5 9.0 2.0 7.8 3.0 0.5 2.0 5.5 0.8 1.5 1.0 1.0 0.5 1.0 0.3 0.8 0.8 3.0 0.5 4.0 3.2 1.5 7.5 4.0 4.0 8.0 0.5 4.5 0.5 2.0 4.5 4.0 7.5 5.5 5.0 5.0 5.4 5.0 4.0 4.5 5.0 5.0 HaO HaO IlaO IlaO Emul. IlaO HaO HaO HaO IES Ilf 6 IlaO IlaO IES 103aO 6 IES IES IES IlaO IES IES IES IlaO IES IES IES IES IlaO Ilf IlaO DaO IES IES IES HaO IlaO HaO HaO IES IlaO IES HaO Type IES IES IES HaO HaO IES IES IlaO Table V.Redshiftsof300ExtragalacticNebulae. (5) (6) W 4 4 4 S” 5 5 5 (7) 3 l’ L PA 1 1 2 3 3 2 1 3 1 6 1* 1* 1 í* 6 i * 2 1 1 1 1* 1* 1 * 1 124*5* Slit 106 170* 165* 8 155* 156* 140* 119 3 109* lf 134* 105* 134 3* (8) 90° 90 85 85 90 50* 90 90 4 90 90 90 90 90 90 71 90 90 90 90 90 90 90 90 75* 6* 75* 3* 84 90 90 90 4* 90 90 90 12t 90 10t 90 12t 90 12f 90 90 6* 90 H 0* 5* No. (9) 3 4* 3 5 2* 1* 1* 5 5 8* 7* 1 10é Lines Wt. AD 4 (10) (11) 6 2 t 10 9 3 94 H Al 4 3 ? 6 4I 3 H 3 4 H ? 9 H 2 i 2 5 5 5 5 *2 4- 6 5 5 H 205 119 125 129 234 174 107 140 132 136 104 ‘74 10 76 11 82 22 19 29 56 34 29 10 99 53 31 13 97 59 18 16 68 57 34 36 38 47 15 14 58 99 86 53 95 94 91 98 34 2 Res. Pl. + 55 + 13 +225 + 49 - 54 + 32 + 9 - 79 + 14 + 49 - 45 + 15 + 25 -150 - 38 - 34 + 92 + 82 - 22 (12) -118 -127 15 12 13 11 30 28 0 0 Redshift c-AX/Ao (- 316) +12418 +11029 +16841 + 1681 +27128 + 1768 + 4485 - 233 - 241 + 1921 - 193 + 1928 + 656 +12567 + 4766 + 2017 + 2084 + 2602 + 1078 + 1802 + 340 + 1558 + 1583 - 244 + 3757 + 4016 + 1734 + 4037124-36+294124 14 + 587 (13) 290 89-20+78 Long. Lat. (14) (15) 296 -83 Galactic 245 -85 105 -61 117 -77 194 -78 102 -31 157 -78 109 -58 105 -50 118 -55+25 106 -34 105 -25+58 121 -43 126 -51 170 -67 121 -43 113 -24 87 -23 86° -21° 88 -23 88 -23 89 -14 89 -21 85 -76 89 -22 88 -37 91 -15 93 -74 Cos A (16) 100 +77 +80 +78 +77 +81 - 6 +78 +67 +21 +77 +22 +78 +31 +42 +31 +10 +58 - 8 +52 - 4 +21 -16 +30 +30 +48 -17 Redshift No. +12658 +11263 + 1663 +17072 +27359 + 2 + 1 + 1831 + 44 + 38 + 4686 Corr. Note + 1987 + 1904 + 1171 +12597 + 890 + 2005 + 2728 + 1877 + 496 + 2177 + 4940 + 1510 + 3847 + 1646 - 70 + 731 + 4106 + 1683 (17) (18) 119 11 10 12 13 O'! V" 1956AJ. X 120 NGC (M77) 1052 1042 *IC 1073 1068 1058 2268 2217 2146 2139 1097 2276 1964 1961 1232 Sc 1187 2300 1889 1888 2347 2336 2314 1744 1640 1637 1569 1518 1453 1331 1300 SBb 2389 2366 *391 *342 1385 1359 1332 1398 1395 (1) © American Astronomical Society • Provided by theNASA Astrophysics Data System Type SBb SBc SBa SBc SBb SBb SBb Neb. Sap Sep Sbc Irr Irr E3 (2) El Eo El E2 E3 E2 Sc Sc Sb Sc Sc Sc Sb Sb Sb Sc Sb Sc Sc Sc So Sb Sc 41 Nov23.3 41 Sept22.4 41 Nov17.2 35 Dec23.2 38 Jan25.2 47 Jan18.3 49 Nov25.4 46 Oct30.5 48 Jan15.2 48 Jan12.2 47 Apr16.3 36 Jan22.7 46 Oct31.5 49 Feb 46 Oct 47 Jan 47 Jan 46 Jan 48 Jan 47 Jan 46 Jan 45 Nov8.95.5HaO 47 Jan 36 Jan 35 Oct 46 Oct21.43.0HaO 47 Jan22.2 36 Nov15.35.0IES 53 Dec3.3 35 Nov 40 Dec 35 Oct 38 Dec 36 Dec9.5 35 Nov27.5 52 Nov25.5 53 Oct12.4 47 Jan16.4 47 Jan17.4 36 Jan23.4 51 July27.3 35 Oct3.5 Mean UT Date (3) 24. 5 28.2 25.4 29.5 21.2 11.2 31.2 21.2 16.3 18. 2 17.2 28.4 16.2 6.5 1.2 THE ASTRONOMICALJOURNAL Exp. Hr. (4) 4.0 2.8 8.6 1.3 3.0 8.5 4. 5 3.0 3.0 3.0 2.0 3.5 7.5 IES 2.8 HaO 2.5 HaO 4.8 HaO 4.0 4.0 4.0 4.0 2.0 2. 5 3.0 4.0 3.5 4.8 IES 5.0 HaO 3.0 HaO 2. 5 3. 5 2.2 HaO 3.8 IES 5.0 HaO 4.1 HaO 2.0 IES 3.0 HaO 5.5 IES 5.0 5.9 Ilf IES 4 HaO IES Emul. Ilf 103aO 6 HaO HaO HaO HaO HaO Agfa IES HaO IES HaO HaO IES HaO HaO IES HaO Type 11200 HaO HaO (5) 6 1 (7) 3 L PA 2 1 * 6 2 1 2 2 2 3 2 2 2 3 2 1 * 2 2 1 * 1 2 2 Slit Table V.Continued. 101° 145* 107 115* 115 106 114 138* 4* 174 118* 117* (8) 90 90 76 63 90 90 90 90 90 90 90 97 90 90 25* 70* 70 46 46 90 90 90 90 90 90 90 90 90 90* 6* 90 10f 90 18 No. Wt. (9) (10) 2 8* 5 5* 4* 4t 9* 4 4* 4* 6 8* 3 3 3 3 6* 6 9* 12^ 9* 4* 5* 5* 4 6 3 5* 2 8* 3 3 3 1* 5* 5 5* Lines 2 1 2 6 2 10 6 H n 4 H H H 4 ? 2Î 4 4 6 4 6 8 2 4 3Î 4 H H 3 5* H 7è 3 1 31 H 5 5 (11) 125 101 167 101 180 AD 103 147 100 103 103 142 103 147 76 36 40 75 67 52 29 38 39 83 44 47 43 95 54 69 66 24 88 82 86 78 25 39 51 51 47 80 36 3 Res. +191 + 5 -136 + 53 - 4 + 94 - 48 - 57 (12) PI. 98 70 33 28 29 56 77 50 Redshift Galactic100Corr.Note c-AX/Xo Long.Lat.CosARedshiftNo. + 355152' + 1523150 + 1424194 + 1121141 + 1874139 + 80115 + 1579179 + 1408180 + 1820176 + 2012186 + 1992176 + 1573 + 1625175 + 4035160 + 34106 + 1524189 + 784103 + 1820183 + 233796 + 1573202 + 3870110 + 2557 + 1607101 + 1676187 + 528167 + 1027184 + 239195 + 1913198 + 1849193 + 2557181 + 676194 + 3951107 + 208895+28+68229237 + 2252102 + 194114 + 4521118 + 3816153 (13) (14)(15)(16) 58 111 -57 -56° -50 -51 -20 -63 +11 -58 -30+142920 -55 -57 +25 +61 +22 +64 -51 -53 +21 +12 +55 -50 -51 +28 +68 +28 +66 -43 -46 -52 -41 +28 -17 -20 -25 -33 -63 -36 -54+151429 -30 -32+43228 +29 -23 -54 +29 +45 +28 +40 +23 +13 +06 +47 +07 -05 -07 -34 +62 -29 -28 -42 -32 -34 +54 -40 -20 -43 +54 -80 -75 -67 +60 + 334 + 1895 + 221 + 1508 + 1322 + 1133 + 1306 + 1538 + 1736 + 1886 + 1471 + 1395 + 1700 + 1896 + 220 + 889 + 3975 + 1333 + 107 + 2535 + 967 + 1688 + 1648 + 4032 + 2595 + 4113 + 229 + 4641 + 2432 + 3858 61, No.1237 (17) 2395 2395 1799 487 (18) 16 15 19 17 18 23 22 21 24 22 25 27 26 30 35 33 32 32 31 36 34 38 O'! V" 1956AJ. X 1956 April *2389 NGC (M81) 2967 2976 2950 2903 2500 2475 ♦IC 3027 [Sc] 2841 2732 2715 2683 2681 2646 2523 2441 2748 2642 2633 2551 Ho II 2537 2525 2835 2805 2787 SBa 2784 2776 2613 3031 (1) American Astronomical Society •Provided bythe NASA Astrophysics Data System Neb. SBb SBc Type SBo SBo SBo SBb SBb [Irr] [E3] Sab [Sc] (2) Sc Sc Sc Sc Sc Sb Sc Sb Sc Sb Sb Sa So Sc So Sc Sc 49 Feb20.3 49 Jan30.3 42 Jan14.4 47 Jan21.5 47 Apr20.3 50 Mar15.3 47 Apr23.3 47 Feb22.3 36 Nov13.5 42 Feb14.3 42 Jan20.4 47 Feb23.2 48 Jan13.4 42 Feb12.3 36 Nov20.5 45 Nov30.4 46 Nov30.5 36 Dec18.5 38 Mar26.9 45 Nov9.5 45 Dec9.4 54 Jan31.5 53 May3.7 53 Apr21.3 38 Jan26.5 53 Mar9.3 53 Feb17.4 54 Jan13.5 50 Mar12.3 53 Mar8.3 39 Apr22.2 42 Jan17.4 48 May12.3 47 Feb24.3 41 Feb4.5 48 Feb15.3 41 Apr23.8 41 Apr19.8 Mean UT Apr 23.3 Apr 23.3 Mar 9.3 Mar 9.3 Mar 9.3 Feb 17.4 Feb 22.3 Feb 22.3 Mar 9.3 Feb 17.4 Date (3) THE ASTRONOMICALJOURNAL Exp. 10.0 17.0 Hr. (4) 6.0 4.0 4.4 6.0 6.0 6.0 4.0 4.2 4.0 4.0 4.0 4.0 1.5 6.0 5.0 3.5 6.5 7.5 9.0 4.0 3.2 5.0 5.0 5.0 5.0 4.1 6.2 5.7 5.0 4. 8 3.5 1.5 5.0 3.3 5.0 5.0 J03aO HaO IlaO IlaO IlaO IlaO IlaO IlaO IlaO Emul. IlaO IlaO Ilf IlaO HaO IES HaO HaO IlaO 11200 HaO HaO HaO IES 103aO 11200 11200 IlaO IES 103aO IlaO IES HaO IlaO 103aO IES IlaO HaO IES Type (5) (6) (7) W 6 2 6 8 6 6 5 6 5 6 L PA Slit Table V.Continued. 157° 120 145* 120* 145* 160 150* 120* 115 175* 112* 174 155* 155* (8) (9) 40 62 27 18 90 90 40* 42* 42* 90 90 90 26* 90 67* 90 90 90 20* 90 18* 90 12 90 No. Wt.AD 4 4* 3 5* 6t 3 3* 5 4 ¥* 3Î 3 4* 4 6t 3 6* 8t 4 6* 4* 4* 6* 3 It It 5t 5t 5t 3 3 3t It It 4* 2* 1* 5* 3t 2 7* 3 3 3 9 It It It It It U Lines 2 2 2 (10) (11) 4 89 P 2i 45 3 H 4 4i 4 H 8 4 f 4 4 H 6 2Î 6 H 4 4 9| 5 1 1 5 5 ? l 6 H H 1 P 1 1 k i ! Î 143 140 100 175 134 66 40 99 30 45 37 26 31 68 75 67 68 48 42 32 70 58 71 27 83 32 30 93 60 10 48 20 26 78 25 79 52 54 50 8 (- 77) (- 81) (- 66) (+216) (- 52) (+156) (+112) Res. + 42 + 11 - 55 (12) + 15 + 45 + 23 + 10 + 79 + 27 + 20 - 11 + 67 + 39 - 13 - 41 - 7 - 78 - 16 - 33 - 39 -104 PI. 59 59 34 20 Redshift Galactic100 c*AX/Xo Long.Lat.CosA + 470136+33+13 + 5019132+32+19 + 3623109°+36°+47 + 290141+34+03 + 2064200+12-80 + 3448107+33+52 + 220111+34+46 + 2296107+33+52 + 2632107+35+50 + 4439198+23-74 + 2228106+35+52 + 1555213+11-91 + 42110+42+43171 + 3546106+35+52 + 909220+20-91 + 551111+39+44 + 708220+17-92 + 2673144+44+01 + 1489104+35+54 + 2121100+33+59 + 1158102+34+57 + 335158+40-17 + 736134+41+14 + 1916117+41+35 + 1079105+40+491226 (13) (14)(15)(16) 2245 205+38-68 1339 122+46 645 177+45 740 134+45 64 108+42+45+71 +27 +14 -38 Redshift + 509 + 3764 + 1824 + 3604 + 299 + 531 + 358 + 4217 + 2384 + 1282 + 5076 + 2782 + 2452 + 2021 + 778 + 1651 + 2298 + 284 + 3702 + 782 + 636 + 683 + 432 + 2676 + 1329 + 2041 + 1420 Corr. (17) (18) Note No. 121 39 42 41 40 43 46 45 44 47 49 48 50 52 51 62 61 60 53 65 64 64 63 63 59 57 55 54 66 66 65 58 56 67 67 68 71 71 70 69 70 O'! V" 1956AJ. X 122 Sex Dw NGC *2574 (M82) *IC 3034 3055 3065 3077 3066 3079 3109 3145 (1) 3159 3161 3163 3169 3190 3184 3259 3239 3198 3310 3294 3319 3359 3338 3370 3389 3395 3396 3403 3432 3430 3419 © American Astronomical Society Neb. Type SBc [Irr] SBc Irr [E3] [E2] Irr [El] Irr Irr (2) Irr So Sc Sb [So] Sc Sb Sc Sa Sc Sa Sc Sc Sb Sb Sc Sc Sc Sc Sc Sc Sc 38 Apr2.8 46 Apr28.3 46 Apr27.3 46 Apr24.3 39 Mar15.2 50 Feb16.2 47 Feb25.2 47 Feb25.2 39 Apr20.3 36 Dec22.5 46 Jan 46 Jan 50 May7.3 47 Jan 49 Apr1.2 47 Feb 41 Jan 47 May 48 Jan 47 Feb21.3 47 Feb14.3 41 Jan 40 Mar 54 Feb 54 Feb 54 Feb 48 Feb13.3 49 Apr27.3 48 Feb15.5 54 Jan 48 Jan14.4 48 Mar1.2 37 Dec3.5 36 Mar26.3 54 Apr30.3 48 Mar8.2 48 Mar3.4 48 Mar3.2 48 Apr1.3 48 Feb16.4 48 Mar2.2 41 Jan31.5 Mean UT Date (3) 28.4 28.4 31.4 20.4 30. 5 11.4 29.5 13.3 10.4 14.2 9.5 5. 5 5. 5 THE ASTRONOMICALJOURNAL Exp. Emul. Hr. Type (4) (5) 4.0 IES 6.5 IES 3.5 IlaO 6.0 HaO 6.0 IlaO 6.0 IlaO 4.0 IlaO 5.0 IES 4.0 IlaO 4.5 IlaO 3.0 IlaO 5.0 IES 4.5 IlaO 3.0 IlaO 4.5 IlaO 4.5 HaO 3± HaO 6.0 HaO 8.0 11200 3.5 HaO 5.0 HaO 5.0 IlaO 3.0 IlaO 5.0 11200 5.0 11200 4.0 HaO 5.5 HaO 5 ±HaO 5.0 HaO 2.5 IES 3.0 IES 5.0 HaO 5.0 IlaO 5.0 IlaO 5.0 HaO 4.0 HaO 3.5 HaO 3.0 IlaO 4.8 112006 2.0 HaO5 5.5 HaO5 5.0 HaO5 (7) (8)(9)(10) L PA Slit Table V.Continued. 150* 155 168* 155 111 116* 116* 125 131 135 150* 65* 65° 65* 65* 65* 72* 90 20 20 20* 4*5^114 90 82 82 90 90 50* 42* 90 40* 87 18* 90* 90 90 14* 96* 70 41* 90 73* 32* Provided bythe NASA Astrophysics Data System No. Wt. 10t iot 10* 4* 4* 4* 4* 4* 4* 5* 7* It 3t 2t It 3 5 4* 4 4 7* 2 8t 2* 5* 6t 3 6t 4* 8t 9t 7* 5* 6 3t 2t 5* 3t 4* 6* 5* 4* 7* 4* 7 7* Lines 1 2 6 3i H 3 4 5 7 6 2 5 8 8 3 4 7 71 5 n 4 H 4 3 (11) 139 AD 179 115 106 142 116 107 185 127 67 84 39 79 83 37 18 56 42 41 76 69 60 87 44 64 30 11 77 68 90 72 39 59 85 37 56 78 99 54 30 55 75 (+359) Res. c*AA/XoLong.Lat.CosA (-208) (-191) (-100) (+134) (+ 35) + 19 + 46 - 19 (12) (13)(14)(15)(16) - 40 + 59 + 53 PI. RedshiftGalactic100 - 27 - 91 68 64 44 24 14 57 30 + 275108°+42°+45 + 1913203+44-61 + 2051105+40+50 + 2132105+40+50 + 1171126+50+21 + 441231+24-91 - 158109+42+44 + 3855221+35-80 + 6950150+57 + 436215+40-72 + 6204150+57 + 6245150+57 + 1380180+56 + 395145+57 + 1312207+47 + 880189+56-39 + 649138+56+07 + 28106+44+46 + 1469150+61-04 + 1866110+47+39 + 1244100+42+52 1008 110+50+37 1330 200+58-43 1400 195+61 1334 203+59 1751 161+64 1643 2982 201+60 1742 162+65 998 124+55+21+1061 826 144+61+01 609 154+65 -05 -05 -05 -60 -32 -37 -44 -12 -07 -12 -42 Redshift No. 61, No.1237 + 410 + 1730 + 2201 + 2282 + 1234 Corr. Note + 168 - 26 + 220 + 3615 + 6935 + 6230 + 1132 + 6189 + 1284 + 395 + 670 + 763 + 166 + 1983 + 1457 + 829 + 1201 + 1119 + 1289 + 1202 + 1715 + 1607 + 2856 + 1400 + 1706 + 588 (17) (18) 100 101 71 102 72 74 73 103 102 75 76 104 105 77 78 79 81 80 83 82 84 84 85 86 87 90 89 88 90 91 96 95 94 93 92 97 98 99 1956AJ 61 . . . 97H 1956 April NGC 3646 3516 3510 3672 3631 3628 3607 3556 3512 (M99) 3887 3810 *IC 4162 4151 4125 4111 4064 3938 4178 4128 4116 4102 4088 4030 3995 3990 3953 3941 3893 4194 [SBop] 3998 4214 4212 Sc 4244 4236 4216 4254 (1) © American Astronomical Society • Provided by theNASA Astrophysics Data System SBc SBo Neb. Type SBb SBo SBc SBap [So] Irr (2) Sc E6 So Sc Sc Sb Sc Sc Sc Sb Sc So So So Sc Sc Sc Sc Sa Sc Sc Sa Sc Sc Sb Sc 48 May3.34.0HaO 48 Apr13.36.0HaO 40 Mar5.23.011200 46 May1.87±HaO 40 May6.35.511200 48 Jan18.45.0HaO 37 Feb10.33±IES 42 Mar21.02±103aO 48 May4.34.0HaO 46 May7.24.0HaO 47 May19.35.0HaO 47 Jan22.44.0HaO 49 Apr22.34.5HaO 46 May7.24.0EaO 48 Apr1.43.0HaO 37 Feb15.43.0IES 49 May3.4 47 June21.2 39 Apr22.4 48 Mar7.5 40 May7.55.51120061 41 May20.810.011200 47 Apr24.35.0HaO 38 Jan25.45.0IES 40 Mar4.43±11200 39 Apr15.812.0IES 37 Apr7.3 54 May6.32.0HaO 38 May26.2 51 July8.2 54 May6.22.0HaO 54 Mar1.3 50 Mar23.43.0HaO 48 Mar6.8 54 Mar1.3 50 Feb23.5 50 Feb23.5 41 Apr21.8 53 Dec14.5 40 Mar5.4 46 May5.3 39 Mar14.4 54 July2.3 Mean UTHr.Type Date Exp.Emul. (3) (4)(5) THE ASTRONOMICALJOURNAL 14.0 4.5 2.9 4.0 2.0 4.5 4.2 2.0 3.0 4.2 3.2 3.2 5.0 6.0 3.0 5.0 6.0 5.5 IES HaO HaO HaO HaO HaO IES HaO HaO IES HaO Agfa 11200 HaO HaO HaO HaO 11200 W (6) (7) 6 6 3 L PA Slit Table V.Continued. 165* 109 103* 150* 125* 147* 150* 166 100 170* 160 152 (8) 90 90 90 83* 90 90 10* 37 90 90 50* 27* 6* 48* 96 90 90 67 96 90 32* 32* 67* 90 48 32* 32* 57* 45* 90 20* 90 n* No. Wt.AD (9) 4* 4* 3* ? 4 7* 4 2t 2 3 5 2t 4 7* 5* 2 4 4 4 4* 7 It 5 4 3^ 3* 6 3* 3 6t 9* 13£ 5* 7* 8 5* 4 9* 3f 3* 5* 5* 5+ 3 8* 3* 5t Lines 2 H H (10) (11) 3 H 4 4 4 2¿ 2 5 2I 7 6 4i l 3 3 9 4 4| 9i 5 175 114 110 120 142 135 136 108 80 68 78 22 85 42 96 28 36 41 77 35 47 47 43 29 28 83 43 65 70 83 55 42 60 55 78 36 59 61 56 13 54 56 59 4 3 9 (-329) (+ 63) (+ 31) (-287) Res. + 18 +100 (12) - 11 -100 PI. 45 16 71 46 13 50 9 6 8 Redshift Galactic100Corr. c-AX/Xo Long.Lat.CosARedshift + 1502170+67 + 871198+67 + 650115+56 + 2632100+43 + 1087115+60 + 842210+65 + 4425197+69-28 + 719170°+68° + 1163250+44 + 1005221+68 + 2045240+48 + 874117+70+16 + 868113+67 + 2546200+82-12 + 239595+48+51 + 148596+52+46 + 870113+73+15915 + 1033222+77 + 1509246+60 + 1059103+61+321155 + 3347152+78-033338 + 934118+76+11 + 1304248+64-43 + 739105+65 + 2585100+62 + 233245+72-30 + 878103+64+29965 + 2793+48 + 318120+79 + 2125242+75 + 59242+75 + 2451245+75 + 265118+78 (13) (14)(15)(16)(17) 1008 107+63 927 138+76 720 103+61 +53 +28 -17 -16 +25 -31 +21 -38 +32 +03 -36 -67 +28 -70 +27 +33 -22 -49 +53 +08 +10 -26 -26 -26 + 671 + 1451 + 2791 + 728 + 778 + 734 + 4341 + 1162 + 897 + 922 + 953 + 1844 + 931 + 816 + 1092 + 936 + 2548 + 967 + 1362 + 820 + 2510 + 967 + 1623 + 1175 + 143 + 2684 + 2047 + 186 + 342 + 2373 + 295 - 19 Note (18) No. 107 106 108 109 110 112 111 114 113 116 115 117 119 118 121 123 122 120 128 125 124 127 126 128 127 129 130 131 132 133 123 O'! V" 1956AJ. X 124 (M104) NGC (M86) (M87) 4256 4293 4291 *IC 4365 (M89) 4386 4401 4486 4406 (M60) 4494 4517 4535 (M94) 4552 4519 4559 4536 4567 4565 (1) 4636 4594 4568 4666 4656 4643 4618 4605 4713 4699 4649 4647 4736 4750 4753 4775 4762 © American Astronomical Society • Provided by theNASA Astrophysics Data System Neb. Type SBo [Sb] (2) E2 E2 Irr E5 E3 Eo El Eo Sa Sc E2 Eo Sc Sb Sc Sc Sb Sc Sb Sc Sc Sb Sc Sc Sep Sc Sb Sc Sb Sop Sc Sa 47 Jun22.33.0 39 May13.34.0 41 May16.33.5 47 May24.34.0 47 Feb22.53.0 47 Jun23.33.3 36 Mar19.45.2 37 Dec7.5 49 Jun24.3 36 Mar26.4 48 Jan19.5 37 Dec1.5 47 Feb25.4 40 Mar12.4 48 Mar8.4 51 July7.2 37 Feb15.52.IES 47 Jan18.4 46 Jun2.34.5HaO6137*4* 47 Jan21.52.5HaO6 38 Apr6.4 48 May6.3 40 Mar6.4 39 Mar15.4 38 Mar31.4 37 Apr17.3 46 May6.3 47 May23.3 40 Mar8.4 47 Jun10.3 47 Apr25.3 47 May15.3 38 May23.3 38 May30.3 47 Jan18.5 41 May17.3 47 May20.3 38 Jun2.3 50 Feb22.5 51 July9.2 Mean UTHr. Date Exp. (3) (4) 23.3 30.3 23.3 30.3 THE ASTRONOMICALJOURNAL 14.4 IES 2.8 2.5 2.0 HaO 3.0 IES 2.0 HaO 3.3 HaO 7.8 11200 5.0 HaO 4.0 5.8 HaO 4.0 HaO43 4.0 HaO56 4.0 6.0 7.1 4.0 HaO53 3.0 5.0 5.0 1120081 5.0 5.0 5.8 5.0 IES 4.0 1120061 3.0 HaO52 4.0 HaO52 4.2 HaO43 4.6 IES6 2.0 HaO42 Agfa 8 HaO 5 HaO 5 Emul. 11200 6 HaO 5 HaO IES IES IES Type W HaO IES IES IES HaO HaO HaO 11200 IES (5) (6) 6 6 (7) 6 L PA 6 1 2 1 3 1 * Í 2 6 1 3 3 1 Slit Table V.Continued. 140* 113 111 112 133* 140* 162 136 134 100 118 123* 8* 123* 7* (8) 172 3* 43* 90 90 74* 90 24 90 90 90 90 80* 90 90 92* 44* 4* 90 10f 70 90* 90 8* 50* 3 90* 90 5*6 30* 30* 30* 5 No. Wt.AD (9) (10) 3 3 2i 3 2 4 4 9t 2t 3t 4* 6* 5 3f 3 4* 8f 4* ?t 5* 5t 4* 4* 4 6 7* 3 3 It 2t It 3 Lines I0i k 1 2 6 2 3 3 3 4 3 H 6 3Ï 3i 162 4 5 41 4i 2i 3 7 8 4i 7 5 5 P i 7i 8 l 2* 1 2i 2i 3 (ID 140 122 130 169 (+256) 67 59 61 61 18 66 32 76 86 32 63 48 68 57 94 68 60 74 33 64 47 99 96 63 24 19 49 33 34 58 64 39 24 50 11 (+228) 89 12 •. (+28) .. (-210) 69 77 63 37 6 (- 83) Res. + 68 + 80 + 28 + 78 + 15 - 65 - 58 - 26 - 24 (12) + 24 + 19 - 43 - 37 + 2 PI. - 2 + 62 + 31 + 66 - 94 Redshift Galactic100 c-AX/Xo Long.Lat.CosA + 258395°+53°+46 + 750230+79-19 + 190392+42+59 + 181192+41+60 + 294118+82+06 + 1290255+69-33 + 1303210+86-06 + 1196255+75-24 + 1218263+63-40 + 2097261+70-30 + 1213260+71-30 - 309251+75-25 + 247261+75-23 + 1927265+65-36 + 856 + 2284 + 1174 + 1207 + 2413 + 1448 + 954 + 484 + 140 + 1645270+62-38 + 72192+85+07 + 1244 + 1432 + 1511272+54-47 + 31386+76+21 + 664273+68-30 + 1364277+61-36 + 164789+45+59 + 997277+74-21 + 1684275+56-43 (13) (14)(15)(16) 217 +87 262 +73 160 +87 270 +64 269 268 +51 268 +74 91 93 +76 +56 +65 +19 +45 -01 -26 -04 -53 -23 -36 -35 Redshift No. + 2080 + 2721 + 1191 + 693134 + 1991 + 312135 + 1124137 + 1098138 + 1285 + 1123140 Corr. Note - 384 + 2007141 + 1819142 + 853 + 178 + 1162 + 1048 + 2206144 + 275145 + 2335144 + 1324147 + 849 + 541146 + 1531 + 1175148 + 1379148 + 1370 + 742149 61, No.1237 + 376151 + 574150 + 1824 + 1256 + 934 + 1555154 (17) (18) 136 135 137 139 143 152 151 153 152 153 O'! V" 1956AJ. X 1956 April *3949 *4040 [Spec] NGC Anon Anon HoIV 4781 4861 4789 (M63) 4900 4889 4848 4793 4902 4907 SBb *IC 4921 4911 4995 4952 5468 5371 5363 5308 5301 5248 5204 5474 Sc 5473 SBo 5198 5068 5061 5055 5033 5005 5653 5533 5585 (1) (2) © American Astronomical Society • Provided by theNASA Astrophysics Data System Neb. Type [Irr] SBb SBc [E5] [E5] [pec] [So] Irr [pec] Irr [Sc] [Sc] E4 El Sc Eo Sc Sc So Sc Sc Sb Sc Sb Sb Sb Sa Sc Sb Sc Sc Sb 47 May22.34.0IlaO 49 May4.4 53 Apr6.4 52 Feb25.4 47 Jun18.3 51 Jun3.3 41 Mar7.5 51 Jun7.3 49 Jun28.3 47 Feb20.6 47 Jun19.3 40 Jun4.3 47 May16.3 51 Jun27.3 40 May10.4 47 May22.3 48 Feb13.5 48 May5.4 47 Jun16.3 47 May17.3 51 Apr8.4 53 May12.3 49 Jun29.34.0IlaO 51 July10.3 46 May7.4 47 May13.3 47 Feb21.5 40 May12.3 38 May24.8 47 May18.3 51 Jun3.3 42 Apr18.3 50 May9.3 50 Apr21.2 51 May7.3 51 May30.3 51 May9.3 50 Apr19.3 53 Apr7.2 51 May28.8 52 July28.2 50 Apr18.3 Mean UT May 27.6 Date (3) THE ASTRONOMICALJOURNAL Exp. Hr. 10.0 (4) 2 ± 4.0 4.0 2.0 4.0 4.0 2. 5 4.0 6.5 6.0 3. 8 7.0 3.0 7.0 4.0 5.0 3.0 5. 5 1. 5 1.0 5.0 3.0 4.0 4.0 2.5 5.0 5.0 6 3.5 5.5 3. 5 4.0 5. 5 7.0 2. 5 8.5 7.0 5.0 5.0 7.0 103aO6 Emul. IlaO IlaO IlaO IlaO HaO IlaO HaO IlaO IlaO HaO IlaO 11200 IlaO HaO IlaO IlaO IlaO 11200 IlaO IlaO IlaO IlaO IES IlaO IlaO 11200 IlaO HaO IlaO IlaO IlaO HaO IlaO IlaO HaO HaO 11200 HaO 11200 IlaO Type W (5) (6) (7) (8)(9)(10) L PA Slit Table V.Continued. 150* 141 118* 150* 105 143* 150* 155 104* 104* 104* 148 118 90 67 64 90 90 90 31 31 90 74* 90 55* 90 90 30 90 29* 60* 90 71 70* 80* 12 90 90 80 90 90 0* 5 lit No. Wt. 3 4 2 3* 4 9* 3 2 6t 5t 4 3* 1 5* 1* 4* 2t 6* 6 6t 3 4 4* 6* 6* 3 5 4* 5* 3 5t 3 3 5* 5* 5* 3t It 4* 5t 6* 9 3* Lines 1 lli P 4 6 2 - 2 5 n 3 5i> 6 3 6 2i 6 6 n 41 4i 4 3 1 6i 139 8 (11) 152 131 AD ’ 37 147 164 106 118 106 97 68 73 67 73 65 77 70 69 14 48 48 46 51 72 21 33 46 47 46 66 32 56 36 38 75 34 14 73 88 53 79 22 71 Res. - 33 +100 -160 f 69 + 19 +117 + 67 - 40 + 78 + 26 - 49 - 50 -104 - 27 - 26 (12) - 30 PI. Redshift Galactic c •AÄ./AoLong.Lat. + 2529 + 7209 + 6585 + 7526 + 7515 + 1054279+64 + 793 +13457 + 5868 + 2758276+47 + 1350279+59 + 263345+70+34 + 1138310+62 + 2035 + 170260+68 + 2065279+35 + 53868+74 + 104162+79 + 1835281+55 + 586521+85 + 1232306+67 + 570280+40 + 90858+78 + 2856305+51 + 149 + 304 + 3557 + 2390 (13) (14)(15) 8372 123+88 8006 2562 5459 2141 66+59+50 895 273+52 272 247 65+60+49 67 +87 30 +87 62 +84 70 +83 12 +86 11 +87 69 +61 68 +69+35 77 +55 80 +58 49 +62 65 +57+54+466177 16 +67 8 +87 5 +86 +86 +05 +86 +05 Cos A (16) (17) 100 +01 +05 +05 -48 +12 +10 +04 +04 +05 +04 -32 +20 -51 +53 +37 +48 +26 +19 +07 +47 -37 -40 -12 -13 -54 -59 -22 +30 +47 Redshift No. + 8375 + 751 + 2544157 + 7538158 + 7224 + 6597 +13487 159 + 829160 + 7527 + 2605162 + 958161 + 5474 + 5883163 + 8021 Corr. Note + 1888 + 968165 + 1715 + 5886 + 1239164 + 2194 + 1813169 + 1193168 + 416167 + 2667 + 408166 + 616 + 1098 + 2735 + 1102 + 290170 + 3647178 + 2531 2790 2291 394 (18) 155 156 172 171 174 173 175 176 125 O'! V" 1956AJ. X 126 Comp NGC Anon Anon 5668 *IC 5678 5676 5713 5746 Anon [Eo] 5846 5850 Anon [Eo] 5857 5866 5907 6027d 6015 6412 Sc 6217 6070 6027a 5982 5970 5949 (1) 6574 6503 Sc 6384 6314 6239 6643 6635 6661 6654 6702 6703 6822 © American Astronomical Society • Provided by theNASA Astrophysics Data System Neb. Type SBb SBb SBb SBa [Eo] [So] (2) [So] E3 Eo Irr Sc Sc Sc E4 Sb Sb Sb So Sb E2 Sc Sa Sc Sa Sc Sb Sc Sb Sa So Sc So 48 May3.4 47 Feb24.5 41 May23.0 40 Jun5.3 49 Jun27.3 50 Apr15.4 46 Jun21.3 51 July2.3 47 Apr20.4 49 May23.3 47 Apr19.4 49 May24.3 50 May9.3 40 May9.3 42 Jun18.4 51 July26.2 48 May12.4 46 Jun4.3 39 May13.4 46 Jun30.3 47 May16.4 46 Jun22.3 46 Jun24.35.0HaO 46 Jun29.3 41 Aug19.3 46 July3.35.0IlaO 47 May15.4 46 July2.3 41 Jun21.3 51 July3.3 38 July1.8 36 Aug24.3 38 Aug27.4 41 Sept23.2 41 Jun22.3 51 July8.4 46 May2.4 49 Jun27.4 49 Jun24.4 46 July31.3 47 July14.3 46 Aug2.2 46 Aug1.3 47 July16.3 Mean UT Date (3) THE ASTRONOMICALJOURNAL Exp. 12. 5 Hr. 10. 7 (4) 4.3 4. 0 2.8 3.0 5.0 2.5 3.2 4.0 2. 5 2. 8 5. 5 6.0 6.0 6.0 6.0 2.0 7.0 4.0 4.0 4.0 2.8 6.0 6.0 6.0 3. 5 3.0 6.0 8 ± 5.0 5.0 5.0 3. 5 3.0 3.0 4.0 3.5 5.0 5.0 5.0 5.0 IlaO IlaO Emul. IlaO 11200 11200 IlaO IlaO IlaO IlaO IlaO IlaO HaO HaO IlaO Type Agfa 8 IlaO 6 11200 6 IlaO IlaO HaO 103aO 6 IES LAO HaO IlaO 5 HaO IES IlaO HaO IlaO IES IAO IlaO HaO HaO 103aO 103aO 6 IlaO IlaO IlaO HaO HaO (5) W 10 (6) 4 8 5 5" 4 6 5 6 4 4 5 5 5 5 6 4 6 6 6 6 6 5 5 (7) s' L PA 3 2 6 2 1 3 3 2 6 6 3 1 6 2 1 3 1 2 2 2 1 3 3 3 2 3 1 Slit Table V.Continued. 171* 113 132* 136* 160* 136* 125* 122* 124* 171 170 177* 113* (8) 122 122 49* 90 57° 90 78 90 90 90 45* 90 80 41* 90 90 90 8* 34* 83 88 90 34* 90 76 65* 83 90 92 90 90 2 No. Wt. (9) (10) lit 6* 4 3 ÏÏ 7* 4* 5* 4* 3 S* I 3 ïï* 4 4 6 3* 3 4* 4* 4 2 3 2* 3 3* 2* 3 4 3 3 8* 3 5* 5t 5 3 5* 3 9t 5* 2 3 n 5t Lines 5 1 2 2 11 3Í 5 8| ? H 5 H 7 2 4 4 H H 4i 4 4 4 2| 8 2 6 5 2i> 3 H 6 2i> 81 2 5¡ (ID 103 AD 118 113 115 202 124 110 114 88 78 89 77 63 23 63 84 60 45 96 98 34 40 40 32 49 35 94 61 25 39 83 56 43 46 79 88 54 58 31 82 30 28 28 26 24 30 30 10 (-152) Res. + 87 - 56 +119 (12) + 25 + 64 + 25 - 59 - 77 - 20 - 6 - 19 PI. + 17 + 9 - 6 - 26 23 21 73 59 Redshift Galactic100 c-AA/Ao Long.Lat.CosA + 1665323°+55°-02 + 224455+60+50 + 230065+54+58 + 1965320+51-06 + 2476329+46 + 2321 + 1774328+47 + 1882323+51 + 4721354+56 +10540 341+48 + 52257+51 + 85058+52 +10546 341+48 + 38066+45 + 4036 + 298160+47 + 2127348+47 + 138278+33+77 + 2120340+34+22 + 44682+46+42 + 73263+43 + 96435+39+73 + 1717358+20+51 + 674812+30+64 + 1682 + 150874+31+81 + 1924 + 4193 + 4708435+97 + 4706 + 2394 + 4794435+97 (13) (14)(15)(16) 2387 10+14+69 5071 11+10+68 33 36 354-20+45 66 +31+85 42 +19 71 +28 72 +28+84 19 +13 42 +19+92 +04 +05 -02 +63 +61 +27 +18 +18 +69 +68 +26 +72 +79 +85 +92 Redshift No. + 2394 + 1659179 + 2474180 + 1947 + 1876 + 2333183 + 1786182 + 2491184 + 1033 + 4802185 Corr. Note +10594 186 + 711 61, No.1237 + 587 +10600 186 + 2205187 + 3185188 + 4594189 + 948 + 1183194 + 2186191 + 4162190 + 1870 + 6940 + 1613193 + 288 + 1751195 + 1934 + 5275198 + 2594197 + 2179 + 4982199 + 4430 + 2670200 + 99201 + 5085204 + 4999205 (17) (18) 181 189 192 196 203 202 203 O'! V" 1956AJ. X Note NGC 1956 April No. *IC *1317 NGC 2. AnonFaintfieldnebulae observedinconnection 7771 7770 7769 7727 7793 7742 7723 SBb 7715 [SBc] 6951 6946 1. AnonFaintfieldnebulaeobservedinconnection 7714 [Spec] 7679 7671 7218 7137 6944 7625 7585 7562 7479 7392 7318a E2 7640 7469 7393 7331 7318b SBb *IC (1) © American Astronomical Society • Provided by theNASA Astrophysics Data System Neb. SBo Type SBb SBb SBb SBc [Sc] [Sep] El (2) E2 Sa Sc Sb Sc Sb So Sc Sc Sa So Sop Sop Sb Sb with aprogramtoobtainradial velocities with asearchforpossiblefaroutlyingglobu- lar clustersassociatedwiththeAndromeda for 1950are: nebula (MayallandEggen1953);positions hm0 40 July31.9 41 Aug 47 July23.43.3IlaO 48 Aug10.3 48 Aug6.3 40 Aug5.0 41 Aug 36 Aug 35 Oct 35 Sept 45 Nov5.2 45 Nov4.2 47 July21.8 47 July21.8 46 Aug4.4 35 Sept24.3 [Ei]:o 2628.0,-1-3912.i(Plate Vb). [E2]: o23i4?,+400(7(PlateVa); 41 Sept 35 Oct 41 Aug25.4 41 Aug1.4 41 Aug2.4 42 Aug15.3 53 Oct 50 Aug 36 Aug23.4 38 July25.8 37 Aug5.4 36 Aug14.4 54 Nov21.24.0IlaO 53 Oct9.3 39 Aug16.4 35 Oct25.2 53 Oct12.2 36 Aug20.4 51 July7.4 51 July7.4 52 Aug15.4 52 July31.4 Mean UT Date (3) 27.2 24.3 27.4 25.3 28.7 12.4 28.2 26.4 27.3 THE ASTRONOMICALJOURNAL Exp. 10. 5 12.0 16.2 12.3 Hr. (4) 6.0 4.5 4.5 6.0 4.5 4.0 6.0 6.0 4.2 4.8 5.0 7. 5 3. 8 2.6 4.2 7.7 5.5 3.0 5.0 2.6 6.0 4. 5 7.7 5.0 4.0 4.5 4.5 6. 5 3.5 3.5 5.0 5.5 11200 IES IES IlaO HaO 11200 Emul. IES 6 IES Agfa 6 HaO IES IlaO IlaO IlaO HaO IES IlaO IlaO HaO IES 103aO 6 103aO 6 IES IlaO HaO 103aO 6 103aO Ilf IES IlaO IES Ilf HaO 6 IES 103aO 6 103aO 6 Type (5) 6 (7) i * 2 1 1 Í* 2 6 6 3 6 6 2 2 2 2 1 1 1 * 1 1 3 1 2 L PA Slit I Table V.Continued. 126 115* 167* 169* 167* 169* (8) 90° 90 90 90 90 90 90 96 72* 90 90 90 90 90 90 90 88 27* 70 85 90 90 90 90 90* 88 10 90 90 90 6 6 NOTES 11* No. Wt.AD (9) (10) 4 4* 4* 4 3 3f 8* 3* 6* 3 3 7t 5 4i 5* 6* 2 9* 4 3 3 2 5* 5* 5* 6* 4* 3 3 5 8* 3t 2t 9f 7 6* 5* 5* 3 5* Notel NGC No. *IC Lines ¥ P 1 8 2 13 12 4i 4è 4 4 3 « 4 H 6 3 4 4i 3 3Î ? 3 9 4 2 5 7Í 7 3 3 3 « 5 5 236 187 114 150 134 165 122 160 173 Í00 (ID 140 140 45 46 43 39 97 43 76 27 80 78 38 81 83 41 94 34 78 33 80 79 92 65 20 83 36 12 59 73 75 8 •+ 84 (+109) (+137) (+ 90) Res. + 39 + 36 + 31 + 68 - 57 - 43 - 91 - 33 - 24 - 82 (12) PI. Andromeda nebula(Mayall1950),since larger redshift,“b”sprextL/IL; forthe shift carriesBaade’sdiscovery designation vey ofthespiralforemissionobjects(Baade on color-filterphotographstakeninhissur- for emissionpatchesassociatedwiththe in M31as“a”sprextI2/H2, theoneof Baade hadfoundthemtoberelativelyblue 1945 and1951);theobjectof smaller red- 43 35 22 86 29 54 77 12 9 Redshift Galactic c-AA/Xo Long.Lat. + 2425 + 4598 + 3975 + 1505 + 586761-21+93 + 6724 + 1808 + 1364 + 187741-68+35 + 3806 + 4692 + 3813 + 2941 + 174867-49+64 + 2795 + 510156-54+59 + 412962-46+69 + 42373-19+90 + 3385 + 91963-21+93 - 70 + 283358-56+56 + 1828 (13) (14)(15) 4276 4338 4349 1973 41-68+36 177 330-78+02 45 -24 20 -21 67 +15 64 +11 61 12° -21° 44 -59 74 -40+72 74 -40+72 74 -40+72 64 -42+74 55 -44 34 -55+54 52 -46+69 10 -63+32 54 -49 9 -21 -52 Cos A (16) +68 +90 +94 +97 +76 100 +93 +43 +51 +66 +72 Redshift No. + 4179206 + 1775210 + 221208 + 1646 + 4826207 + 6146213 + 7003211 + 1937 + 3975 + 3037 + 1198 + 4554228 + 1940 + 1982 + 2081224 + 2963223 + 2641215 + 4899214 + 183230 + 4492229 + 4565227 + 3001222 + 5278221 + 4336 + 693220 + 2050216 + 3538 + 4004 Corr. Note (17) (18) 209 212 212 226 225 221 220 219 218 215 217 127 O'! V" 1956AJ. X Note NGC 128 2I No. *IC 10. *79Brightestmemberingroupdiscussedby 11. 428Only3727intwoemissionpatches.42"NW 12. 604BrightestemissionpatchinM33;plates 13. 864Narrownuclearspectrum;early-typecon- 14. AnonBrightest(npr)ofclosepair“disrupted 22. 1331,1332Slitsimultaneouslyonbothnebulae. 21. 1300Slitonbar. 25. *342Early-typecontinuousnuclearspectrum 24. 1385Early-typeabsorptionspectrum,withHßin 3- 59Slitonbarandtwoemissionpatches;strong 20. 1187Nuclearabsorptionlinesofpoorvisibility; 15. 1052Spectrumpreviouslydescribed(Mayall 16. 1068Emissionspectrum(PlateIVd);broad, 17. 1073Slitoncentralbar. 18. 1097North-precedingpartofdoublenucleus. 19. 1097South-followingpartofdoublenucleus.. 4. 205Hydrogenlinesunusuallystrong(PlateIVb). 3. 185Strongauroralspectrumsuperimposed. 6. 224Nucleus,driftedlengthofslitforallplates. 5. 214OnlyHandKmeasured. 9. 278Stronghydrogenabsorptionlines. 7. 224Onmajoraxis,14Í0sprnucleus;absorption 8. 255Absorptionlinesbroadandindistinct. © American Astronomical Society • Provided by theNASA Astrophysics Data System 0 hm h0 ho length ofabout4065A(PlateIVa);en- latter onlyafairlystrong3727couldbe ho ho hanced aurorallineat3914;positionsfor measured onthespectrogramsatawave h 35mo8?9,+3938Í3;fainterstar18" consists oftwoSb’sincontact;Nebula“b,” 33Í8; brighterstar55"NE;actually“a” NW, brighterstar58"W,andfainter,dif- fuse nebula48"SE. lines inunresolvednebulosity. 1950 andidentifyingconfigurationsare Shapley andBoyd(1940). (Plate Vc):Nebula“a,”o3453H,+39° lines Hß,Hy,and3727,thelatteralsobeing departure fromrotationalvelocitycurve and 48"SEofcenter,onmajoraxis. 0 galaxies” describedbyZwicky(letterOct. tinuum, fainttíandK,with3727,Hô,Hy, taken tocheckearliervelocitythatindicated and Hßinemission(PlateIVc). tion for1950is2+189'. present inthefainter(sf)component;posi- by Seyfert(1943);apparentabsenceofab- bright bandsstudiedspectrophotometrically spectrograph. sorption HlineofCa11,althoughKis 16, 1953);redshiftmeasuredfromemission from thelongwardcomponentofwide pair 3868and3967of[Nein]. present, isduetosuperpositionofemission emission spectrum(PlateIVf). Hß andHyinemission(PlateIVe). (Mayall andAller1942). with Hßinemissionandabsorptionlines emission. (1936) inconnectionwithperformanceof one offoursuitableformeasurementred- nearly invisible;theplatelistedisonly shift ;theothersare: The probableabsenceofcondensations hav- ing strongemissionlinesisalsoindicated by 1941 Sept.29.4,4,Ilf,ó^Xi',90;nu- a slitlessgratingspectrogram,kindly taken 1941 Nov.19.3,8,Ilf,6“X3',98 1941 Nov.22.3,6,Ilf,6"X6',35 clear continuousspectrumthatshows only Hßinweakemission. condensations inthespiral;noemis- sion linesshowontheseplates. nucleus andorientedtocover THE ASTRONOMICALJOURNAL61,No.1237 jsiit on several Note No. 26. 27. 29. 28. 30. 32. 31- 33- 34- 35- 36. 38. 37- 40. 39- 42. 41. 43- 44. 45- 46. 47. 48. 49. NGC 1518 Early-typespectrum(PlateIVg)withbroad 2139 3419 3403 3646 3628 3512 35IO 3990 3938 3646 3556 3995 3938 3887 3672 3938 *IC 3396 Slitsimultaneouslyonbothnebulae; 0 IVc Very broad,indistincthydrogenabsorption Emission patchnearendofbarapproxi- Slit alongbright,elongatedcentralregion. lines. Slit alongbrightcentralbar,whichmakes Nuclear region;absorptionlinesbroadand Slit onbrightcentralbar;broadandfaint mately 55"Nofnucleus. This nebulaisthebrightestofthose uncom- near centerofbar. and Hyinemissionsmall,brightnucleus only asmallanglewithmajoraxis;broad, ably isrealandduetorotation,butamount NE ofnucleus;differenceinvelocityprob- Condensation inarmapproximatelyno" faint. absorption lines. lane. Absorption linesofpoorvisibility(Plate Strong hydrogenabsorptionlinesandearly- Very broadfaintabsorptionlines. Very strong3727withearly-typecontinuum, ous emissionlines(PlateIVn). strong, early-typecontinuumwithnumer- nearly invisibleabsorptionlines,withHß lump atendofplate. type continuum. clei showemissionbands.Ithas beenexten- is uncertainbecauseofpoorqualitylines. toward Hßbecauseofpresenceemulsion axis ;spectrumisprogressivelyoutoffocus Hß and3868[_Nein]infaintemission;ab- This nebulaisoneoftheuncommon,highly and HyHßinemission(PlateIVo). mon, highlyconcentratedspirals whosenu- slit wasorientedonlyabout30fromminor Slit onnucleusandemissionpatchinarm sorption linesofpoorvisibility. On slitsimultaneouslywith3998;faint concentrated typewhosenucleusshowsa Only 3727inemissionpatch130"NEof Hy and3727inemissionpatch90"SW Faint nebularspectrumconfusedwithstrong center. very reliable;nevertheless,theSWend end ofslit,sodifferenceinredshiftisnot Emission Hßand3727inemissionpatch Only HandKinnucleus. by Seyfert(1943). spectrum ofverybroadbrightbands;itis lines measurableinnucleusandpatch,since 40" SEofcenter;redshiftismeanall nucleus. Only HandKinnucleus;slitacross Slit onbrighternuclearregionnorthofdark tem; HßandHypresentinfaintemission. one ofthosestudiedspectrophotometrically Broad, poorabsorptionlines. Early-type continuumwithstrong3727; auroral spectrumsuperimposed. and twooutlyingemissionpatches(Plate redshift isuncertain. probably isapproachingwithrespectto Redshift isforapproximatecenterofsys- nucleus. Nucleus only;absorptionlinesarefaintand night-sky spectrum;redshiftuncertain. 70" SWofnucleus;patchfellonextreme ^ THE ASTRONOMICALJOURNAL Note NGC 140. 4519 139. 4517 138. 4517 141- 4535 143- 4536 142. 4536 145. 4605 144. 4567, 127. 4178 137. 4486 136. 4401 131. 4214 129. 4194 128. 4178 132. 4236 130. 4212 135- 4401 134. 4293 133* 4244 No. *IC 4568 Slitsimultaneouslyonboth nebulae. Slit onnucleusandseveralcondensations, Fainter andfollowingoftwo;abrightfore- ground staris20"NWofthispatch;3727 Slit ontwoemissionpatchesnorthside Slit onnucleusandraystructureNW;scale Fainter oftwoemissionpatchesapproxi- much weaker5006and4958[0in] which donotshowemission. of centralpartdarklane;brighterand redshift asthenucleus;however,ray ration ofspectranucleusandray;also, Slit ontwobrightestpatchesinbrightcen- which appearstobeaforegroundstarpro- This highlyconcentratedpeculiarspiral, bar andpatchissosmallthatitsinterpre- line spectrum. ence inredshiftdeterminedbyagrating features (Mayall1934),forapossiblediffer- sively observed;foritsprincipalspectral Strong 3727andbroad,faint absorption result forpatch. Slit onnucleusandemissionpatch;redshift faint lines. Nuclear absorptionspectrum,withbroad, across fulllengthofslit. may befaintlypresent,andslightlyinclined, preceding oftwo. identification asaradiosource. nebula havebeendiscussedbyBaadeand the structureandHumason’sspectraofthis spectrum isdifferentinnotshowing3727; faint absorptionfeaturesthathavethesame the raycontinuousspectrumissonarrow of Crossleyalmosttoosmallforgoodsepa- jected onfaintnebulosityofthespiral. Slit onnucleusandcondensation40"NE, Hß andHy. Hb ;emissionfeaturesare:strong3727,and tation asrotationalmotionisuncertain. center ofbar;differenceinvelocitybetween Emission patchapproximately100"SWof files (Seyfert1943). the constancyofAX/XwithX(O.C.Wilson lines. Emission patchapproximately75"Eof is fornucleusonly,sincerotationmayaffect that itisuncertainwhetherthereareany is cataloguedas4395;thetwolinesmeas- Brightest oftwoemissionpatchesapproxi- Only HandKmeasured;auroralspectrum tral bar;strongemission-linespectrum a strong,early-typecontinuumwithbroad observed withthree-prismdispersion,shows Bright centralbar;redshiftfromabsorption- nucleus. mately 50"SWofbrighterone. mately 125"SEofcentersystem,which superimposed. tem. Redshift isforapproximatecenterofsys- Brightest emissionpatchinSEend,approxi- hydrogen absorptionlinesbeginningwith Minkowski (1954)inconnectionwithits ured are3727andHy. may beaffectedbyrotation. mately 5Í5fromcenterofsystem;redshift 1949), andfordetailedemission-bandpro- (Adams andHumason1936),foracheckon (Plate IVr). 0 61, No.1237 O'! V" 1956AJ. X Note NGC 151- 4736 150. 4713 149. 4656 148. 4647,. 147. 4643 146. 4618 1956 April 156. 4789 152- 4736 159. Anon 158- *3949 157- 4793 155- 4775 154- 4775 153- 4736 160. 4861 163. 4907 161. 4900 162. 4902 165- 5033 164. Anon 167. 5204 166. 5068 No. *IC 168. 5248 169. 5301 170. HoIV 171. 5468 © American Astronomical Society • Provided by theNASA Astrophysics Data System 0 h0 49 Slitsimultaneouslyonbothnebulae174. Slit oncentralbar;strong3727andcon-172. Slit onbrightcentralbar.173. spicuous hydrogenabsorptionlines. ent nuclearregion,whichisattheSWend lines and3727.179. which hasbroadhydrogenabsorptionlines178. of thebrighterhalfnebula. tem andapproximately18"Woftheappar-176. Nuclear region;redshiftfromabsorption of poorvisibility. Nuclear regionandinvolvedfaintemission177. Brightest emissionpatchnearcenterofsys- patch approximately15"Eofnucleus, which givevelocitiesaffectedbyrotation. Fainter partofspiral-arcring60"SE181. Brighter partofspiral-arcring50"NW velocity affectedbyrotation. nucleus; 3727andemissionHyHß,180. Only HandKmeasured. is averageofmeasurementsforboth,since Slit onnucleusandemissionpatch;redshift nucleus ;only3727,whichgivesanuncertain Emission patch30"Sofnucleus.182. spiral isnearlynormaltolineofsight. (Plate IVs).175- Only HandKmeasured.185. lines measured. cleus; 3727,HyandHßaretheemission184. Emission inregionofarm30"NEnu-183. Auroral spectrumsuperimposed.188. redshift maybeaffectedbyrotation. Slit oncentralbar. region ;faintabsorptionlines. Slit onshort,brightandelongatednuclear intense 3727astheonlymeasurablefeature. No. 46;strongearly-typecontinuumwith Humason andZwicky(1947)blueobject Slit oncentralbar;weakplate,onlyG-band Bright emissionpatchinSWendofsystem;186. Slit onshortcentralbar;broadabsorption Shane on20-inchastrographplate;weak measured. lines onstrongnightskyspectrum(Plate189. faint star30"NEofpatch. approximately 60"Sofcentersystem;187. Irregular spiralorpossibledwarfsystemat by Holmberg(1950);slitontwoemission measurable strength,isofemissionpatch spectrum, showingonly3727andHyin in linewithaforegroundstar,whichisdis-192. system; patchesare20"apartandnearly Peculiar-type spiralinM101groupstudied190. patches approximately30"SWofcenter191. iVt). visibility. nearer patch. tant 50"inpositionangle70fromthe Broad absorptionlines,fainteronesofpoor193. i3mo, —3i8'(1950)notedbyC.D. Weak platethatshowsbroad,faintabsorp- tain. 194. tion lineswhosemeasurementwasuncer- brighter oftwoemissionpatcheslocated each sideofcentersystem;brighterpatch Holmberg (1950);redshiftisforslightly195. Dwarf nebulainM81groupdescribedby one 70"SW. is approximately50"NEofcenter,fainter on whichonly3727wasmeasured. Emission patch55"Sofnucleus ; weakplate196. 2 THE ASTRONOMICALJOURNAL131 Note No. NGC 5468 Emissionpatch55"Sofnucleus;stronger 5473 Slitonbrightcentralbar,whichisnearly 5468 Emissionpatch33"Nofnucleus. 5468 Nucleus. 5668 Slitonnucleusandcondensation35"NE, 5678 Absorptionlinesareofverypoorvisibility 5653 Nucleusandadjacentfaintemissionpatch 5585 Slitonnucleusandcondensation50"SE, 5474 Theredshiftindicatesthatthisnebulaisa Anon Thesetwonebulaeareinaclouddescribed 5713 Slitonthreecondensationsincenterof 5846 Companion40"Sof5846. 5850 Slitonfaintcentralbar;3727veryin 5846 Slitonandclosecompanion;3727very 5857 Slitonelongatednuclearregion,whichcor- 6070 Emissionpatch70"NEofnucleus;differ- 6070 Slitonnucleusandemissionpatch;redshift 6027a Secondbrightestnebulaincompactgroup 6027d Brightestnebulaincompactgroupdescribed 5982 OnlyHandKusedforredshift;wideslit 5970 Slitoncentralbar,whichnearlycorresponds 6217 Nuclearspectrumofearly-typecontinuum *IC 6412 Slitonnucleusandcondensation35"N, 6239 Redshiftfromstrongemissionspectrumof 6503 Auroralanddawnspectra confusedwith h Shane ona20-inchastrographplate. which doesnotshowemissionlines. in thispeculiar-typespiralnotedbyC.D. the minoraxis. plate showsnumerousemissionlines. and weredifficulttomeasure. member oftheM101groupstudiedby Hy, andHßinemissionmaybethenucleus; Holmberg (1950). faint in5846. exposure ismuchinferior(PlateIVv). early platetakenwithwiderslitandlonger auroral spectrumsuperimposed(PlateIVu); nebula; thecentralonethatshows3727, which showsweakemissionHyand3727. by ShaneandWirtanen(1950);the1950 cause ofweakplate. be inclined,butinclinationisuncertainbe- responds closelywithmajoraxis;linesmay rated by123"inpositionangle45°,isI5 nuclear spectrum. redshifts werequotedbyShaneandWir- following relativelocations:one15"NW, there aretwofainternebulaenearitinthe tered regionofthecloud(PlateVe,1),and to bethebrightestandlargestinthisclus- 20^4, 4-8°47';thefirstonelistedappears position forthetwoobjects,whicharesepa- to majoraxis. tanen (1950). the other45"SW;preliminaryvaluesof from nuclearspectrumofabsorptionlines. described bySeyfert(1951). by Seyfert(1951). and darkplateobscureotherlines. encial velocityprobablypartlyduetorota- with absorptionlinesofverypoorvisibility; tion, sincepatchisnotfaroffmajoraxis. redshift from3727andtheKline(Plate which showsnoemissionlinesexceptpos- IVw). sibly averyfaint3727;absorptionlinesof patchy, centralbar. nebular spectrum. measurable innucleusforredshift. poor visibility,withonly3727andHline O'! V" 1956AJ. X Note NGC 203. 6822 202. 6822 200. 6703 204. Anon 201. 6822 198. 6635 I97- 6574 132 I99. 6702 205. Anon 211. 7318a 213. 7318b 212. 7318a 210. 7137 209. 6946 206. *1317 215* 7479 214. 7469 208. 6946 207. 6944 measurements. because ofthepossibilityrotationaffecting mination oftheredshiftincolumn(13),generally 216. 7625 No. *IC vational resultsinfamiliarandconvenientunits, pressed inkm/sec,accordancewithcurrent without involvingthemootquestionofradial ciable forthelargervelocities, andthesecorrec- this procedurehastheadvantageofgivingobser- Mount Wilson-Palomarpractice(Bowen1953); recession, second-ordercorrections becomeappre- motion; for,iftheredshiftsarevelocitiesof Column 13.Theobservedredshift,cAA/Ao,ex- © American Astronomical Society • Provided by theNASA Astrophysics Data System h Absorption linesbroadandfaint;early-type This low-latitudeobject,inaCrossley-plate A spectralfeaturemeasuredas3727isex- faint, broademissionfeatures. continuum withHyandHßpresentasvery extragalactic. mine itsnature;theredshiftshowsitis fainter magnitude,wasobservedtodeter- field devoidofnebulaecomparableand Humason’s (1931)publishedredshiftof with thosefromotherlines. tremely faint,butitsredshiftagreesclosely Pease, refersto6703. Hubble’s gaseousnebulaeIandIII,meas- extend fromoneobjecttotheother. ured asoneobjectsincetheemissionlines Hubble’s gaseousnebulaX(IC1308). Hubble’s (1925)gaseousnebulaV. graph plate;theobjectis5Í4NWof Brightest memberinlow-latitudegroupof Following memberofclosepairinStephan’s bright star+39°3968(PlateVf,1). nebulae ata:=i95=+40°17'(1950) Preceding memberofclosepairinStephan’s Faint absorptionlinesdifficulttomeasure. Fainter emissionpatch165"SWofnucleus. described inprecedingnote;theobjectis Second brightestmemberinsamegroup noted byC.D.Shaneona20-inchAstro- +2250 km/sec,basedonapoorplateby Slit simultaneouslyon7318aand7318b. cleus; nearlocationofthethirdsupernova brightness. This objectistheconsiderablybrighter found inthisspiral(Mayall1948b). Brightest emissionpatch250"NEofnu- brightness. This nebulawasobservedtocheckitsextra- lines. plate fieldlackinginnebulaeofcomparable member ofapairnebulaeinCrossley- galactic nature,becauseitisinaCrossley- another pBstar(PlateVf,2). Early-type continuumwithfaintabsorption Slit oncentralbar. whose spectrumshowsbroademissionbands This spiralhasabright,semi-stellarnucleus quintet. quintet ofnebulae. plate fieldlackinginnebulaeofcomparable 5Í9 NEofBD+40°3948and2^" studied spectrophotometricallybySeyfert on anearly-typecontinuum;ithasbeen (1943)- THE ASTRONOMICALJOURNAL61,No.1237 hm Note NGC 217. 7640 219. 7640 218. 7640 225. 7723 224. 7723 223. 7715 222. 7714 221. 7679 220. 7640 228. 7770 227. 7769 226. 7723 229. 7771 230. 7793 relativity theoryisused. tions aredifferentdependingonwhetherornot logue, orcomputedfromOhlsson’stables(1932) b, generallytakenfromtheShapley-Amescata- based ontheHarvardpoleata=I240and from thenebulatoanapexat/=55°and 8 =+28°(1900). 300 km/sec,representrounded-off valuesdiffer- 6=0°; thesecoordinates,andasolarmotionof ing lessthantheirprobable errorsinthepreferred No. *IC Columns 14,15.Galacticlongitude,/,latitude, Column 16.100cos^4,whereAistheangle This highlyconcentratednebulahasan Faint emissionpatchinarmapproximately Very faintemissionpatchinarmapproxi- SE ofnuclearregion;abrighterstaris20" Bright emissionpatchapproximately225" Faint spectrumofapparentlybroadand both membersofclosepair;strongearly- Slit simultaneouslyonnuclearregionsof absorption lines. Nuclear region;redshiftisfrom3727and blended andKmeasuredinthe Slit onnucleusandfaintcentralbar;only faint absorptionlines,whichgivealow- lines, fromwhichtheredshiftwasdeter- type continuumwithnumerousemission absorption lines;theemissionare3727, early-type continuumwithstronghydrogen 23" NWofnuclearregion. NE ofthispatch. A.D.; nebulartypeinPettit’s(1954)list Spectrum showshydrogenabsorptionlines and 3727confusedwithstrongnight-sky tical outlineoffaintouterpartsspiral; Slit onmajoraxisasestimatedfromellip- shows broadandfaintabsorptionlines,with Weak spectrumofsemi-stellarnucleusthat mined. Hß, andNiof[0in]. mately 52"SEofnuclearregion. emission exceptforaweak3727inthe Slit onpatchycentralbar,whichshowsno lines weremeasuredwithconsiderableun- Strong early-typecontinuumand3727,pos- of poorvisibilityandaveryweak3727. spectrum thatleastaffectswhich nebular spectrumoffaintabsorptionlines nucleus. violet. becoming conspicuousfromHôtotheultra- continuum withhydrogenabsorptionlines nucleus; nuclearspectrumisanearly-type sibly inclined;broadandfaintHK appears tobeslightlyinclined. a veryfaint3727. precision redshift. faint 3727;thisspiralhasbeenstudied Slit onnucleusandcondensationapproxi- probably interchangedwiththatfor7771. mately 95"SW,whichshowsonlyavery photometrically byShapleyandMohr certainty, whichaccountsforthelarge (1938). X O'!V"

KO : 1956 April THE ASTRONOMICAL JOURNAL 133

solution of Humason and Wahlquist (1955) for KO< tional information regarding more accurate loca- O'!LO the solar motion referred to the local group nebu- tions in case of uncatalogued or very faint nebu- lae ; the tabulated numbers multiplied by 3 lae, detailed spectral characteristics when these therefore give the solar-motion corrections ap- appear to be of unusual or special interest, slit plied to the observed redshifts in column (13) to orientation with respect to features in the pro- give the corrected redshifts in column (17). jected nebular image, and references to published Column 17. Redshift corrected for solar motion reports or descriptions that contain supplemen- and given to the nearest km/sec only in case tary information. subsequent small corrections are applied; the Systematic Differences in the Redshift Lists. A general order of accuracy is indicated by the comparison of Tables I and II with V shows that A.D. in column (11). 114 nebulae were observed in common at Mount Column 18. Numbered notes that give addi- Wilson-Palomar and at Lick. For these nebulae TABLE VI. MEAN WAVE LENGTHS OF SPECTRAL FEATURES Absorption Rel. Wt. Emission Rel. Wt. 3770.48 Hl l6 3728.16 0 II] 405 3798.60 Hd 24 3868.58 'Ne m" 26 3835-57 Hrj 32 3968.70 >em]+iie(=)* 2 3888.22 HÇ 26 3969.30 _Ne 4 3933-28 Ca il, K 384 3970.09 He 6 3968.38 Ca il, H 301 4101.67 Hô 36 3968.54 H(2)+#€(l)* 10 4340.38 Hy 79 3969.01 H(i)+H€(2) 37 4362.78 [0 m] 6 3969-23 H+#€(=) 34 4859.90 Hß 42 4101.25 m 120 4957.02 [0 in], N2 18 4226.84 Ca I 8 5006.27 [0 in], Ni 26 4303-52 G band 140 4340.61 Hy 36 * Figures in parentheses denote hypothetical intensities of the unresolved components; for absorption H-\-He they were estimated from the intensities of K and Hô; for emission [Ae m]+Ü€, from 3868 and Hd. TABLE VII. DISTRIBUTION OF REDSHIFT DIFFERENCES No. 185 205 214 221 25 224 278 604 IC342 1332 2681 1569 2903 2146 3034 2217 3169 2683 3516 1052 3031 3556 1097 3184 3810 1889 3310 4214 SexDw IS 3941 4216 3190 SH 3998 4594 3953 1068 4102 4736 4111 1395 4151 HZ46* 4406 1453 4254 5005 5198 2300 4494 5055 5371 2314 4552 5248 5633 4291 4565 5363 5713 4365 925 2787 4636 5846 5746 4762 2841 2950 5033 Comp** 5970 5857 4125 2537 3607 5308 6027a 6015 5866 4535 1637 4649 4486 5907 6070 602 7d 5982 4889 2613 5668 6384 6217 6574 6703 7331 5473 3893 7679 7469 6702 6946 7318a 7625 5850 6944 6661 7793 7479 6822 7727 7585 7742 6643 73i8b Interval -151 101 - 51 — i o + Si + 101 + 151 +201 Lick minus (km/sec) — 200 —150 —100 -50 +50 + 100 + 150 +200 +250 MtW-Palomar Totals 4 5 7 26 28 19 15 114 * Humason-Zwicky (1947) blue object No. 46. ** Companion to 5846.

© American Astronomical Society • Provided by the NASA Astrophysics Data System O'! V" 1956AJ. X Table VIIisahistogramofthecataloguenum- The frequencydistributionissomewhatskewed, These differencesrangefrom—177to+229km/ with anexcessofpositivedifferencesobtainedin bers, fordifferenceswithinintervalsof50km/sec. 134 the senseLickminusMountWilson-Palomar. grams weremeasuredgreaterby28km/sec. on theaverage,redshiftsCrossleyspectro- km/sec. Thissystematicdifferencemeansthat, sec, andtheirmeanwithrespecttosignis+28.4 when consideredintermsofdisplacementonthe the ordinaryphotographicregion,28km/sec redshifts representsanearlynegligiblequantity little advantagetocarrythedetailedcomparison lengths, measurementsofindividualspectralfea- difference, detailedinformationregardingwave Lick plates. Foradispersionof300to400A/mmin of theMountWilson-Palomarplatestoaccount Common difference of28km/secbetweenthetwosets much further.Thereasonisthatasystematic for somelargedifferencesofeithersign,thereis While similarcasesmightalsobecitedforsome dark andgrainy(experimentalIa-0emulsion). exposed, affectedbynightsky(10hours),and volve Crossleyplatesthatarerespectivelyunder- exposed orpoorforotherreasons,differences difference. Whenoneorbothredshiftsforthe consistent explanationwasobtainedfromcom- tures, andplatequalitywasexchanged.No MtW+P ample, thethreelargestpositivedifferences, tended tobelarge,withapreponderanceofposi- same nebuladependedonplatesthatwereweakly tion betweenspectrogramqualityandsizeof parison oftheparticularwavelengthsorlines tive onesforinferiorCrossleyplates.Forex- used, buttherewasfoundtheexpectedcorrela- +229(7318^, +223(6944)and+188(6643),in- SBo, a Mag. She SBb Irr To trytofindthesourceofthissystematic Cat. All 120/120 Sc Sb Sa So % 100 E : © American Astronomical Society • Provided by theNASA Astrophysics Data System IncludesredshiftforNGC4027 observedonlybyStruveandLinke(1940). 4O/4O 28/28 Totals 19/19 —30° THE ASTRONOMICALJOURNAL61,No.1237 *49/51 46/5940/6645/7662/10865/12571/188 *13/14 13/13 11.7 11.6 'A 4/4 4/5 2/2 7/7 5/5 96 786159575238 25 32 9 16/22 4/4 4/5 3/4 4/4 5/5 8/13 1/1 20 35 9 6 10/19 12.0 0/1 <5/7 12.1 S/7 5/12 S/ 7/9 1/2 1/3 30 16 6 corresponds toaboutonemicron,whichisclose estimated errorsinTablesIandIIthe tral featuresofinherentlypoorvisibility. to thelimitofmeasurement,especiallyforspec- average deviationsinTableV.Ifthetwoseries pears smallwhencomparedwiththeredshift comparable accuracy,withthedifferencesfor of redshiftobservationsareassumedtobe objects incommontreatedasresiduals,thenthe km/sec. correction of—0.1to—0.2mag.,neitherthese Thus theredshiftsusedinPartIIIforcorre- probable errorofasingledifferenceis±62 of redshiftsinordertoreduceittheother. systematic correctionwasappliedtooneseries by itoJmag.fromthephotoelectricones,and scale andzeropointaresubstantiallycorrectin whole sky,andsecond,becauseithasbeenshown, observed incommonatMountWilson-Palomar lation plotsarestraightmeansforthosenebulae the cataloguezeropointappearstorequirea though someofthecataloguemagnitudesdiffer terms ofmodernphotoelectricstandards.Al- and laterbyPettit(1954),thatitsmagnitude classes ofthebrighternebulae.Forthisstatistical while toindicateinsomedetailhowrepresenta- and atLick. initially byStebbinsandWhitford(1937,1952) photometry ofthebrighternebulaeover used, first,becauseitstillistheonlyavailable purpose, theShapley-Amescataloguemaybe has beeninvestigatedinPartIIIseparatelyfor tive thespectrographicdataarefordifferent the varioustypesoffieldnebulae,itseemsworth the relationshipbetweenredshiftandmagnitude 13/29 I2.3 12.2 9/10 0/1 4/S 2/3 3/5 5/7 8/13 i/3 32 16 A systematicdifferenceof28km/secalsoap- As aresultoftheforegoingcomparison,no Observational SelectionoftheRedshifts.Since n/17 10/11 17/36 12.4 12.5 6/16 9/11 2/2 3/3 3/9 1/3 27 41 6 6 20/24 1 13/41 11/25 12.7 12.6 3/6 5/ 2/4 S/ 3/7 1/1 49 25 9 13/26 18/23 12/55 9/32 9/18 12.9 12.8 2/14 6/14 1/4 1/2 27 54 10 498/793 63 IOO/112 134/256 52 43/65 38/58 21/46 82/146 54/74 Totals 12/15 14/21 223 370 96 <13.0 66 73 46 66 89 67 80 56 % O'! V" 1956AJ. X Ima logue andphotoelectricmagnitudesshownosys- five-magnitude rangefromapproximately8.0to circumstances islikelytoaffectseriouslythe electric photometryofthebrighternebulaewould served forredshift.Thereasonisthatoverthe following statisticsonthebrighternebulaeob- on thebasisofcomparisonsthathavebeen tematic trend.Undoubtedlyacompletephoto- made bythephotoelectricobserversmentioned, change thenumbersinfollowingtable,but, vals of0.2mag.intheShapley-Amescatalogue. according toclassificationsbyHubble,forinter- as toinvalidatethestatistics.TableVIIIgives 1956 April lae, respectively,theircomparisonshowsthe the numbersofredshiftsandnebulae,arranged slant linesarenumbersofredshiftsandnebu- there islittlereasontoexpectchangessodrastic proportional completenessoftheredshiftdata. magnitudes <11.6and<13.0,respectively,in 3-° Pg-g*>meandifferencesbetweenthecata- Cumulative totalsalsoareincludedtocatalogue the secondandinnext-to-lastcolumn;for divided sofinely.Thereisdefiniteevidence,how- series, andthoseincommon. the latternumbersareexpressedinpercent ever, thatalargerproportionoftheearliertypes was observedforredshift,butthepreponderance is notaccuratelyestablishedforthedatasub- the numberofredshiftsdeterminedintwo in thelastcolumn.Thelowestthreelinesshow for E,Sb,andSc,theproportionalcompleteness lae ofagiventypeandmagnitude,exceptpossibly is notbyalargefactor.Eveninthefaintest lae arebetterrepresentedthanthoseoftypes Sb+Sc onlybythefactor(31/49)/(21/87)= magnitude group,12.8and12.9,theE+Sonebu- 46 to89percent,orbyafactorof1.8.Butthis in thelastcolumn,percentagecompleteness 2.6. Onacumulativebasisto13.0mag.,asshown brighter magnitudes. of redshiftsforthedifferenttypesrangesfrom to themuchmorecompletecoveragefor smaller factoris,ofcourse,dueinlargemeasure centages inthefourthlinefrombottomof observations areessentiallycompletedownto and foralltypesprobablyisgivenbytheper- selection intheredshiftsaccordingtomagnitude whole magnitudeintervalthe spectrographicdata the table.Thesefiguresshowthatredshift fail ofcompletenessbyabout 50percent. 11.6 mag.,butthatneartheendofnext Since thefigurestoleftandrightof Because thenumbersarerathersmallfornebu- A morerealisticindicationoftheobservational A fairappraisalofobservational selectionin © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL o greatly changedbymoreaccuratemagnitudesfor of apossible800,foranoverallcompleteness the redshiftsprobablywouldbestatement appreciably reviseupwardsomeofthecomplete- 200-odd nebulaesouthofdeclination—30may individual nebulae,buteventualinclusionofthe are availableinroundnumbers500redshiftsout pling to13.0mag.,andthatthislimitthere that TableVIIIshowsnolargegapsinthesam- ness ratiosinTableVIII. 63 percent.Thisresultisnotexpectedtobe The measuredapparentmagnitudesbyPettit reported inPartsIandIIofthepresentpaper. exist inthesepublishedmagnitudesdepending have beenreportedelsewhere.Systematicerrors angular diameterofthenebula.Thisaperture upon theratioofmeasuringapertureto effect hasbeenremovedfromthepublishedmag- Table Aiofthisappendixgivesthecorrected nitudes bythemethoddiscussedinAppendixA. which redshiftsareavailable.Thesemagnitudes photographic magnitudesfor576nebulae are referredtoastandardisophoteofabout25 (1954) andbyStebbinsWhitford(1952) mag. persq.sec.ofarc. that thenebulardistributionischaracterizedby discussion mayconvenientlybetreatedonthe and Wirtanen1954,firstofaseries),thepresent Neyman andScott1952,firstofaseries;Shane a predominanttendencytocluster(Zwicky1938, superposed. Onthemoreelaboratestatistical basis ofthemuchsimplifiedpicturenebulae field andclusternebulaeismerelyoneaccording model ofcompleteclustering,thisseparationinto in thegeneralfieldwithoccasionalgreatclusters to thesizeofcluster.Onthistheoretical sible andthesewouldbeconsideredhereastruly picture, clusterswithonlyonememberarepos- All richeraggregatesareconsideredwiththe containing from1to50membersasfieldnebulae. isolated objects.Weshalltreatallaggregates cluster data. The redshiftsarecorrected forthesolarmotion is governedbytheobservationalapproach.Two from effectsextraneousto the problemathand. rections aremadetobothquantitiesfreethem numbers, 3(=AX/X)andm,areobserved.Cor- with respecttothecentroid ofthelocalgroup. 0 PART III.DISCUSSIONOFTHESPECTROGRAPHIC Introduction. Thenewredshiftdatahavebeen Although itisbecomingincreasinglyevident The philosophybehindthepresentdiscussion AND PHOTOMETRICDATA 135 O'! V" 1956AJ. X This correctionismadebecauseitappearslikely within thelocalgroup(Hubble1936a;Humason that thesystematicredshiftdoesnotoperate shifts ofitsmembersreflectthemotion and Wahlquist1955)thatthemeasuredred- 136 The observedmagnitudesarefreedfromthe sun withrespecttothesenebulae.Thecorrection galaxy bytheequationsAP(Z>)=0.25(escb—i) latitude-effect causedbyobscurationinourown for solarmotionisdescribedinPartsIandII. by tance relationoftheformcz=Hr,withrdefined for photographicmagnitudesandAV(5)=0.18 in thefollowing,andzwillbeofform the relationbetweenm—Am(b)K,calledme values inTableIIIandthemagnitudesreported vide thedatafordiscussionof[logcz,ni]re- in TableXIIprovidethedataforclusters. lation forthefieldnebulae.Humason’sredshift eter H. heterochromatic magnitudesarefurtherchanged proper definitionofdistanceareglossedover. The theoryandcomputationoftheKcorrection contained inalaterequation usedforthecluster treat thisproblem,andtheir resultsareimplicitly together withthemagnitudesinTableAi,pro- for PandVmagnitudesisgiveninappendixB to abolometricmagnitudescalebytheKcorrec- Both Robertson(1955)andMcVittie(1956) contain the[logcz,m~\relationfor(1)field corrections tothemagnitudes,suchasso- for thecasewhereStebbins-Whitfordeffect tion, whichaccountsfortheeffectsofredshift. with aprovisionalvalueoftheredshiftparam- called energyandnumbereffects,arenotmade, is alsogiven.TheKcorrectionaccountsonlyfor the interpretationofdata. absorbed intothetheoreticalequationsusedfor as wasoncethecustom,sincesucheffectsare bration oftheserelationsintermsdistance the selectiveeffectscausedbyredshift.Other the valueofKduetopresencethiseffect nebular clusters.AppendixCcontainsthecali- nebulae, (2)selectedisolatedgroups,and(3)the (esc b—i)forphotovisualmagnitudes.These (1948) iszero.Discussionofthemodificationto The redshiftcataloguesofTablesIandV, Here alloftherefinementsrequiredfora The FieldNebulae.Foralinearredshift-dis- The sequelisdividedintothreesections.These © American Astronomical Society • Provided by theNASA Astrophysics Data System log r—[mAm(b)KM+5]/5, Wo =5logcs+(if-H).(1) THE ASTRONOMICALJOURNAL data. Fortherelativelyclosefieldnebulaesuch refinement isunnecessary.Equation(1)neglects we lookbackintimetoeventswhenlightnow another effect.Duetothefinitespeedoflight, distances. Thus,theobservedpairs[logcz,m] observed wasemittedfromnebulaeatdifferent cosmic times(seee.g.Robertson(1933)fora just thelight-traveltimebetweensourceand definition ofcosmictime),thedifferencebeing refer totheconditionofuniverseatdifferent This timeeffectisnotimportantfordistances dition oftheuniverseatanygivencosmictime— lae withthesimplifiedequation(1)isadequate requires knowledgeoftheformexpansion. picture” totheso-called“worldmap”—thecon- the observer.Totransformobserved“world divided into7groupsforanalysisaccordingto for thepresentdiscussion. majority ofthefieldnebulae.Interpretation such that3Í,andthisisthecasefor Table IXgivestheresultingsolutionsandprob- between thecorrectedphotographicmagnitude the [logcz,m]relationfornearbyfieldnebu- Formulae baseduponthemethodofTaylorseries one compatiblewithcurrenttheories.Thecom- value ofApreciselyto5.Differencesinthemean least squares.Thelinearityoftheredshift-dis- for eachgroup.Linearrelationsoftheform nebular type.Figures3to10showthecorrelation scatter inthe[logcz,m]pairs. somewhat unrealistic,duetothenatureof puted probableerrorsaremerelyformaland are thoseofSolution2sincethiscaseistheonly able errors.ThelinesdrawninFigures3to10 adopts Aas5.000andtreatsBunknown. siders AandBasunknowns,whileSolution2 solutions weremadeforeachgroup.Bothsolu- assumption thatthevalueofHisunique.Two are obtainedfromthedifferencesinB,on absolute magnitudeM(m)forthenebulartypes a spreadinapparentmagnitudeatgivenlogcz. among thenebulaeappearsincorrelationsas tance relationistestedbytheclosenessof P =—AP(6)KandlogczcAA/Xo lae fromtheresidualsof [logcz,m]plot,but made toderivetheluminosityfunctionfornebu- tions includeallthedata,butSolution1con- Pc =Alogcz-\-Bwerefittedtothedataby the resultswereaffectedby thehighlyselective Indeed, earlyattempts(Hubble1936c)were (Robertson 1955)areemployedforthisproblem. c (1) Thelargespreadinabsolutemagnitude The nebulaeinthegeneralfieldhavebeen This scatteriscausedbyatleastfoureffects. 61, No.1237 O'! V" 1956AJ. X corrected tothegalacticpoleandforselectiveeffectsofredshifts. Theredshiftsthemselveshavebeencorrectedfor the solarmotionwithrespecttolocalgroup. random motionofthenebulaethemselves.The 1956 AprilTHEASTRONOMICALJOURNAL exact sizeoftheserandom motionsisnotknown sum ofthesystematicdistanceeffectand nature ofthedata.(2)Redshiftsrepresent yet, buttheyseemtobe of theorder200to 300 km/sec.Whentheyare ofthesamesizeas (Figure 3.Theredshift-magnituderelationforEnebulaeinthe generalfield.Theapparentmagnitudeshavebeen © American Astronomical Society • Provided by theNASA Astrophysics Data System 3.0. (3)Theotherpartof thelargerscatterat plains partofthelargescatter atlogczlessthan about thedistanceeffect.Thiscircumstanceex- from the[logcz,ni]relationwilloccurif peculiar motionsthemselvesaresymmetrical the distanceeffect,unsymmetricaldeviations 137 O'! V" 1956AJ. X Objects suchasthedwarfirregularsoflowsur- small czisexplainedbyaselectivityeffectfavor- each other,butevenmoreseriousisthedifference face brightnessaredifficulttoidentifyandob- ing thenearerofintrinsicallyfaintnebulae. are missingfromthediagramsforlargerredshifts serve atlargedistances,andhencethesepoints observed scatter. and zthemselvescontainerrorsofobservation, 138 shows theseerrorstobesmallcomparedwiththe but thediscussioninPartsI,II,andAppendixA than aboutioookm/sec.(4)Thevaluesofm the twohemispheres.TheAvaluesdifferfrom last twosolutionsofTableIX,togetherwith value of5.000. greatest weight,N=474,givesthecomputedA all datainthefirst8groupsofTableIXare and asyetunexplained,differenceexistsbetween south galacticpolarregionswith\b\^30°.The relations weremadefornebulaeinthenorthand as 5.028=t0.116comparedwiththepredicted consistent withalinearlaw.Thesolutionof Figures 11and12,showtheresult.Asignificant, Within thetotaluncertaintiesofsolutions, To checktheisotropyofredshiftlaw,cor- © American Astronomical Society • Provided by theNASA Astrophysics Data System Figure 4.Theredshift-magnitude relation for Sofieldnebulae. THE ASTRONOMICALJOURNAL61,No.1237 o o Solution 2.Thesouthernnebulaeappeartobe of 0.70mag.inBbetweenthehemispheresfor Table VIIIofPartIIshowsthattheredshift observational selection,sincemanynebulaein shift. Partofthisdifferenceisprobablydueto brighter thanthenorthernonesatsamered- would beofinterestandimportancetoassemble catalogues areessentiallycompletefornebulae declinations notreachablefromtheselatitudes. South ofthisdeclinationveryfewredshiftsare satisfy 6>30°Sbutnoneè30°N.It logue showthat37nebulaebrighterthanm^g— brighter thanm=11.6northofô—30. the southgalacticpolarcapareinhighsouthern the southernhemispherecouldcontributesig- made withthefieldnebulae.Observatoriesin so thatanunbiasedtestoftheisotropycouldbe more complete.CountsintheShapley-Amescata- since thedatafornorthernhemisphereare selective effect.Comparisonofthenorthwith nebulae brighterthanPc=11isaresultofthis available. ThescarcityofpointsinFigure12for south galactichemisphereisthereforebiased, [log cz,m]dataforthesebrightsouthernnebulae 11.6 aresouthof3=—30.Allthesedonot vg Figure 5.Theredshift-magnitude relation for Safieldnebulae. O'! V" 1956AJ. X o with highphotometricprecision fromMount question ofisotropy. nificantly towardansweringthisfundamental declinations. Thisisadifficult regiontoreach Wilson duetothestrong Los Angeleslightsin nebulae southoíb=—30areathighsouthern 12 maybeduetophotometricdifficulties.Many 1956 AprilTHEASTRONOMICALJOURNAL A smallpartofthedifferenceinFigures11and © American Astronomical Society • Provided by theNASA Astrophysics Data System Figure 6.Theredshift-magnituderelationforSbfieldnebulae. ciable anisotropyoftheredshift lawisprovided ford’s, andHolmberg’smagnitudecataloguesin lack ofoverlapinPettit’s,StebbinsandWhit- Figure iiand12,strongevidence againstappre- suggestion ispossibleatpresentbecauseofthe the southlatitudes. the southandwestquadrants.Nocheckonthis Whatever thecauseof differencebetween 139 KO O'! V" X

1956AJ. \ 140THEASRONMICLJU61,No.1237 data. Furtherworkonthefieldnebulaeisre- quired forasatisfactorysolution. from thehighdegreeofisotropyincluster © American Astronomical Society • Provided by theNASA Astrophysics Data System Figure 7.Theredshift-magnituderelationforScplus8.redshfit-magnitudeSBo Figure 9.Theredshift-magnitude relationfor SBb fieldnebulae. SBc fieldnebulae.plusSBa 0 0 All Types5.028 SBo+SBa 4.854 All Types6-757 All Types5.102 b Z+30±.208 lute magnitudesarereflectedinthedifferences b ^-30±.412 types ofnebulae,differencesintheirmeanabso- the presentsampleiscomparableforvarious Neb. TypeA Sc+SBc 4.329 To theextentthatobservationalselectionin SBb 5.618 Sb 5.181 Sa 4.717 So 4.630 E 5.882 TABLE IX.SOLUTIONSFORTHEFIELDNEBULAE ±•385 ±•337 ±•312 ±.672 ±•377 d=.n6 ±•378 ±•347 Solution i2 — 10.6365.000 —6.618 5.000 -4.324 5.000 -1.931 5.000 -4.974 5.OOO — 7.4005.OOO -3.466 5.000 -3.4OI 5.OOO -2.843 5.OOO -4.250 5.000 db.182 ±.261 ±.252 ±.307 rb.229 ±.234 ±.246 ±.129 ±.169 ±.283 B A -4.570 27 — 4.40076 -4.030 90 -4.235 474 —4.070 67 -4*375 117 -3-950 36 -4.360 54 -3-895 257 -4.595 132 ±•175 ±.243 ±.212 db.260 ±•358 ±•253 ±•233 ±.128 ±.219 ±•165 B N O'! V" 1956AJ. X lated inTableIX.Xexhibitsthesediffer-thesolutionusingalldata.Tabulatedagainare between thevaluesofBfromSolution2tabu-enees,normalizedsothatAM—0.00mag.for 1956 AprilTHEASTRONOMICALJOURNAL141 © American Astronomical Society • Provided by theNASA Astrophysics Data System O'! V" 1956AJ. X signs forAMindicatehigherluminosities. the numberofnebulaeNineachgroup;negative 142 © American Astronomical Society • Provided by theNASA Astrophysics Data System Figure ii.Theredshift-magnitude relationforfieldnebulaeofalltypesnorthgalacticlatitude +30°. SBb All Types Sa Sb Sc+SBc So E SBo+SBa TABLE X.DIFFERENCESINMFOR Type 8 10 12 141618 20 FIELD NEBULAE THE ASTRONOMICALJOURNAL61,No.1237 + .29 + .21 +.17 -•33 — .12 — .16 -.14 AM .00 474 117 N 27 36 90 67 54 76 P-AP(b) -Kp errors forB,rangingfrom±0.21mag.theE which only27nebulaeareavailable,therange ences is0.62mag.WiththeSBb’sexcluded,for are thefaintest.Thetotalrangeofdiffer- of nebulaealongtheentiresequenceclassifi- illusory, andthatthemeanabsolutemagnitudes nebulae to±0.36mag.fortheScplusSBc,show becomes 0.43mag.Thesizesoftheprobable that mostofthecomputeddifferencesinMare tically thebrightestwhileSBo’sandSBa’s According tothistable,theSBbarestatis- O'! V" 1956AJ. X 1956 AprilTHEASTRONOMICALJOURNAL Mioi groups,theLeogroup,andStephan’s well-known, isolated,physicalgroupsofnebulae different forsamples. very largedispersion,arenearlyconstantforthis cation, excludingtheirregularswhichshowa particular sample.Duetotheeffectsofobserva- grouping beforetheredshiftdatabecameavail- pected fromthegeometricalaspectsof Quintet. Manyoftheseaggregatesweresus- such asthelocalgroup,nearbyM8iand tional selection,theseresultsmay,however,be able. Theredshiftlistsprovideapowerful covering newones.Whilethe generalproblemof method forconfirmingsuch groupsandfordis- the small-scalenebulardistribution fornearby Isolated Groups.Thereexistinspaceseveral © American Astronomical Society • Provided by theNASA Astrophysics Data System 0 Figure 12.Theredshift-magnituderelationforfieldnebulaeofalltypessouthgalacticlatitude—3°* steps towarditssolutionmaynowbetakenwith systems isnotconsideredhere,itevidentthat due tothespreadinluminosityfunctionfor the presentredshiftdata. for selectingnebulaewithsimilarabsolutemag- nebulae. Ifsomeapriorimeanswereavailable a morerefinedanalysisofthedatawouldbe nitudes, thisscatterwouldbecomesmallerand gates ofmoderatetolargepopulation,sincesuch homogeneous nebularsamplemightbefound possible. Itisreasonabletoexpectthatsucha among thebrightestobjectsinphysicalaggre- nebulae wouldbechosenfrom adefinitepartof tested andconfirmedby analysis of27groups the luminosityfunction. This expectationwas The largescatterinFigures3to12isprimarily 143 O'! V" 1956AJ. X 144 Fornax Cl1380 © American Astronomical Society • Provided by theNASA Astrophysics Data System G3190 3190 G3158 3158 G2832 2832 G1600 1600 G2563 2563 c AX/XoNGC Gi068 1068 G1023 IO23 Name, Pop., G741 741 G194 194 G128 128 G564 564 G507 507 G383 383 6000 4812 4758 4657 127 6785 71 1196 3177 6268 575O 4664 495 5298 1631 1399 1604 1073 5264 380 G68 68 G80 80 513 891 20± 72 20 30db 2831 20 2562 40d= 1404 20 ±560 35 ±499 10 182 12 83 12 379 5 3193 8 1601 9 6 925 5 1087 5 125 Anon Anon 3185 1003 1058 375 386 388 384 385 69 THE ASTRONOMICALJOURNAL 11 TABLE XI.DATAFORREPRESENTATIVEGROUPSOFNEBULAE I3.O II424 12.1 I2722 12.0 I252I 13.0 7OO8I 14.6 51042 13-3 6895i 13.7 48522 14.3 6012I 13.4 4664i 14.9 4895 12.0 4728I 11.1 I3023 11.0 18852 11.6 18953 12.6 4384i 14.1 67452 15.6 70325 15.6 68624 14.5 68163 10.9 I706I 13-2 5237I 14.4 72OI2 11.3 18352 -5 741 II.4 2214 13-3 53605 13-6 5790i 10.2 2463 10.1 6472 12.9 5637i 13-7 5923i 13.9 43064 12.5 5121i 15.6 62099 15-3 57538 14.2 45996 14.0 50435 13-7 45393 13-7 55722 13.2 5086i .... 4228 13-9 55782 12.8 45672 15-3 53127 Pc cAX/XoRank 9.8 IO82I 9.5 709i III8 3 4594 5423 Stephan’s 7318a Quintet 73i8b Leo Gr3627 G7619 7619 G7385 7385 G7242 7242 G6928 6928 G6027 6027d G5077 5077 G5049 5049 G5846 5846 G537I 5371 c AX/XoNGC Name, Pop., 3836 7562 7738 6703 7319 6122 4647 6927 4364 1808 5838 788 3368 20± 7626 13± 7386 20± 3623 15 Anon 15 10 5813 5 7317 5 6930 8 5 6027a 5 5353 Anon 7617 7623 76II 7335 7320 3384 3351 3379 3626 3605 3338 3608 3389 3593 3412 3377 3810 3607 3489 3628 5854 Anon 5854 5850 5831 5806 (12.2) 120117 12.3 3953i 14.9 42686 14.4 60312 14.3 6960i 13-9 36595 13-5 35794 12.7 40043 12.6 35532 14.3 74232 13.9 8054i 14.8 70143 13-5 5972i 15-0 45173 13.4 44192 13.i 4994i 12.5 2515i 14.7 4568i 14.0 22928 12.5 16447 12.1 22844 iI.3 2694i 13.7 26003 11.6 42714 11.1 880iI 11.0 136210 10.9 8189 10.9 5728 10.8 6496 12.5 16966 11.7 24125 12.3 13074 11.8 14413 11.7 i8902 11.2 1782i 14.0 60018 12.0 111716 12.0 120215 ii-5 73513 ii-3 59512 10.5 5535 10.4 7304 .... 6272 .... 6576 9.9 7923 9.9 5882 9-5 633I Pc cAX/XoRank 6935 4 4659 4159 .... 5 728 7 61, No.1237 O'! V" 1956AJ. X distance, wouldinvalidate anattempttofinda 200-inch telescope. schraifierkassette, methodsbySandageusingthe large systematicmagnitude error,dependingon paramount forthesephotometric data,sinceany the 6faintestclustersweredeterminedwith 60- and100-inchtelescopes.(3)Magnitudesin by Sandagein2ofthebrightclusterswith and byStebbinsWhitford(1952),with photographic methodsbyBigay(1951).(2)Pho- vidual membersofthenearbyVirgoClusterwere toelectric measuresweremadebyPettitin9and measured photoelectricallybyWhitford(1936) cisely definedwiththeclusterdata. 26 clusters.Photometricdataareavailablefor in thesearchforapossiblesecond-orderterm provide thehomogeneityofsamplesoimportant clusters ofnebulaepermitthedeepestpenetra- therefore, becarriedfartherandmorepre- the redshiftlaw.The[logcz,rn}relationcan, tion intospace.Furthermore,thesesamenebulae tude, dataforthebrightestmembersofgreat groups areclosertousthantheVirgoCluster. redshift parameterH. These aretheNGC1023andLeogroupswith rank ofthemembernebula.Onlytwo27 will eventuallybeimportantinevaluatingthe mean redshiftsof+513and+788km/sec,re- magnitude correctedforlatitudeandKeffect, umns containtheNGCnumber,photographic 18 ofthesefromthefollowingsources.(1)Indi- spectively. Duetotheirproximity,thesegroups the redshiftcorrectedforsolarmotion,and tion, andthemeanredshift.Theremainingcol- ignations takenfromtheNGCnumberof sion oftheclusterdata. brightest member,theestimatedgrouppopula- studied. Listedincolumnonearethegroupdes- 1956 April populous aggregates,isimportantinthediscus- restricting attentiontothebrightestnebulaeof of the27groupsisatleast0.5mag.brighterthan group notonlyhassmallerscatterthanFigure the meanlineofFigure10.Thepointsfor19 found withtheredshiftdata.The[logcz,m] the meanline,while8aremorethan1.5mag. the 27groupsareatleast1.0mag.brighterthan relation forthefirst-rankedmemberofeach magnitudes. Thebrightestmembernebulafor23 this line.Theincreasedhomogeneity,gainedby brighter, and5morethan2.0mag.brighter io, butitshowspreferenceforhighabsolute The problemofthemeasuringaperturesis Tables IIandIIIofPartIgiveredshiftsfor Table XIgivesthedatafor27groups The ClusterData.Foragivenapparentmagni- © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL 0321 and0925+2044were measuredfromi-mm satisfactory results. field whosemagnitudesweredeterminedbypho- measured onplatesmadewithjiggle-camera and theinternalmagnitudeagreementwasgood. squares, since2-mmimages weretoofäintfor throws of2mm.Thetwofaintestclusters0855T in twocolorswasmadeforthesestandardstars average ofthreeindependentintercomparisons tographic intercomparisonwithS.A.57and68 faint clustersandwerecalibratedbystarsineach 0.10 mag.Thesetestswereconsideredsatisfac- Magnitudes for4ofthe6faintestclusterswere tory andthecurrentprogramwasbegun. distribution ofresidualswhosedispersionwas from thoseofNassauandSeyfert(1945),witha magnitudes thatdidnotdiffersystematically brated withfieldstarsofknownmagnitudegave selected globularclustersinM31.Platescali- objects ofappreciablediameter,wasmadeon curacy fortheplates.Asecondtest,usingdiffuse with thepresentequipment.Thoroughtestsof Squares of1,2,and4mmonasidecanbemade schraffierkassette imagesplusthemeasuringac- procedure testedonlytheuniformityof sidual withoutregardtosignwas0.02mag.This and Johnson(1950)weresmall;themeanre- check theinternalconsistencyofmethod. schraffierkassette platesofSelectedAreas61and before thestartofcurrentprogram.First, (Stebbins, Whitford,andJohnson1950).An the standardmagnitudesofStebbins,Whitford, 68, takenwiththe200-inch,weremeasuredto this techniqueandpresentequipmentweremade images givesthemagnitudesofobjects. bration, measurementofthedensities nebulae areindistinguishable.Afterpropercali- large enoughsquares,theimagesofstarsand discussed inAppendixAcanbeappliedwith lation. Theprocedureforaperturecorrection Residuals fromthecalibrationcurvesdrawnwith a mechanicaldevicecalledjiggle-camera.For a photographicplateinrectangularpatternby scription oftheschraffierkassettemeasuringtech- lae becometoosmallformeasurementonthe second-order termintheredshift-magnitudere- images ofuniformdensityobtainedbymoving 48-inch Schmidtplates.Todiscusspossiblesys- procedure fails,becausetheangularsizesofnebu- 25,000 km/sec.Formoredistantclustersthis success fornebulaewithredshiftslessthanabout nique isnecessary. tematic magnitudeerrorsforfaintclusters,de- Schraffierkassette platesweretakenforthe6 A schraffierkassetteplatecontainssquare 145 O'! V" 1956AJ. X nitudes. Experience,bothbyHubble(1936c)and on theapertureeffectinthesefaintnebularmag- sizes ofthesejiggle-camerasquaresforacheck electrically withlargeapertures.Dosquaresof of diffuseobjectsgivemagnitudesthatdifferby from thetestsonM31objects,hasshown less than0.1mag.fromthosemeasuredphoto- that squaresof2.5timestheapparentdiameter 146 criterion? Thescaleatthe200-inchprimefocus 2322 +1425 2308+0720 Virgo* give magnitudestothestandardisophotefor lens, sothatschraffierkassetteimagesof2mm is ii'ioypermmwiththeRoss//3.67corrector of angulardiametersvaryinverselywiththered- brightest nebulaeoftheVirgoClusterareabout neglects relativityeffects.Theaperturesthat shift. Thisprocedureassumesalinearlawand clusters isBootes(1431+3146)witharedshift are 22''1onaside.Thenearestofthe6faint Appendix Agiveanestimateofabout0.2mag. <5705+3506 system asthenearbyclusters.Thecurvesof Since themeanredshiftforthisclusteris+1136 ber nebulaeofthisclusteraretoosmalltobe of +39,400km/sec.Thediametersthemem- they maybecomputedbyassumingthatratios determined onthe48-inchSchmidtplates,but 0106— 1536 Coma* the BootesCluster.Thiserrorapproacheszero km/sec, thecorrespondingangularapertureat i and2mmforthe6faintclusterssatisfythis 0138 +1840 0025+2223 Perseus* for theapertureeffectofbrightestnebula Hercules 22.1 =1.9togivemagnitudesforthebrightest is, therefore,inadequatebyafactorof(17X2.5)/ 0855+0321 the BootesClusterisabout17".Athrowof2mm Bootes Clustermembersonthesameisophotal 0925+2044 1520+2754 1239 +1852 1145+5559 10'. Whitford’sapertureforNGC4594was7Í5. 1024 +1039 1055+5702 1431+3146 The questionarisesoftheadequacy Name © American Astronomical Society • Provided by theNASA Astrophysics Data System * Virgo Coma Perseus o 256 359 201 264 118 106 116 150 116 108 194 178 63 53 10 85 10 l 16 I-3-5-IO I-3-5-IO I-3-5-IO +87 +43 — 12 +81 +54 +60 -48 +55 +20 -44 +75° +55 +66 -77 +31 +45 -40 -42 THE ASTRONOMICALJOURNAL 21,533 12,821 47,835 40,360 39,367 23,365 21,651 19,489 13,187 10,400 60,526 15,781 15,519 57,498 51,908 c AX/Xo 6,657 5,433 1,136 TABLE XII.PHOTOMETRICDATAFOR18CLUSTERS 4889, 4789,4921,4853 4594, 4486,4382,4374 1275, 1270,1278,1273 (18.22) (18.58) (17-93) (19.26) P (uncorrectedforlatitudeandKeffect) I3.O2 15-41 16.25 14.85 I2.9O I7 .II 16.57 15.20 15-88 15-34 18-59 18.40 9.2 ist 3rd5th10th i8 (18.36) (19-15) (18.33) (19-56) I4.47 16.14 16.3216.£ 15-47 13-31 16.67 16.96 15-74 I5-87 I4.8I 18.80 .5 9.8 first ranked. standard isophoteforthelargestnebulawould redshift is+51,900km/sec,theapertureof cluster measuredwith2-mmsquares.Sincethe 0321), witharedshiftof+60,500km/sec,i-mm be about13".Anapertureeffectalsoexistsin for the10thbrightestnebulabecausethesefainter nebulae averageabout+3thediameterof degree thanare2-mmsquaresfortheBootes squares areinadequatetoasomewhatgreater the factoris1.5.ForHydraCluster(0855+ the measuredmagnitudesbutitissmaller,since of theuncertaintyinsizeeffect,no determined magnitudesaregiveninthedata lated dataforthese6clusters,i.e.,thedirectly- aperture correctionshavebeenmadeinthetabu- Cluster, sincetheaperturefactoris2.5.Because remember thatthetabulatedmagnitudesfor order trendfoundinthesequel. of theclustermember.Theexistencethis in theredshiftlawitisthereforeimportantto table. Inthediscussionofsecond-orderterm small systematicerrorisnottooseriousbecause from 0.0to0.2mag.,dependingupontherank 6 faintestclustersaretoofaintbyvaluesranging of PartI.Thisredshiftisacombination(1) for solarmotion,computedfromTableIIorIII the signofcorrectionstrengthenssecond- tory. Column4givesthemeanredshift,corrected mean oftheredshiftsclustermembers,and the internalvelocitydispersionremainingin the systematicdistanceeffect,(2)thatpartof 18 clusters.Thefirst3columnsareself-explana- The cluster0138+1840isthemostdistant (18.73) (18.78) Table XIIgivesthedatanowavailablefor (19.66) (19-30) 16.13 14.49 16.70 16.22 13.60 16.89 18.84 18.88 9-9 (19.26) (19-25) (20.16) (19.72) 16.80 14- 75 16.60 15- 77 14.52 19-38 19.14 10.3 V (uncorrectedforlatitudeandKeffect) 14.10 14.12 15.08 13.70 14-37 12.24 16.00 11.69 16.57 15- 38 14- 77 16.86 17.04 17.08 17.32 17.70 8.3 ist 3rd5th10th 15.01 14.22 15.66 14.86 14.87 13-24 13-74 17.00 12.16 16.97 17-65 17-35 18.00 17-65 8.9 15-77 15-39 14.82 15-83 15-17 13-35 17.42 17-37 I5-78 12.55 17.62 17.80 17.79 18.10 9-1 61, No.1237 16.04 15-72 15- 63 13- 54 17.90 14- 55 13.60 17.89 18.60 18.22 18.13 17.90 9.4 O'! V" 1956AJ. X 1956 April which islargerthanthesystematicdistance internal velocitydispersionshouldbesmall.For all butthenearestthreeclusters,effectof effect. Thismakestheadoptedmeanredshiftof the VirgoCluster,spreadinredshiftsfor as farthesystematicdistanceeffectiscon- the individualmembersisabout2000km/sec, cerned. Noinformationisavailableonthesize and 10thclustermembers.Themagnitudesfor small spreadinthe[logcz,m~]correlations.Col- selves, butitappearstobesmallbecauseofthe isophote bytheprocedureofAppendixA,while the first12clustersarecorrectedtostandard and photovisualmagnitudesoftheist,3rd,5th, values wereobtained,thephotographicmagni- measured. For2ofthe6faintclusters,both umns 5to12ofTableXIIgivethephotographic photographic andphotovisualmagnitudeswere the valuesforlast6clustersaredirectlyas of thepeculiarmotionsclustersthem- for theseclusternebulaedeterminedbyStebbins tudes werefoundbyapplyingthecolorindices measured ;forthe4whichonlyphotovisual and Whitford(1952)by(1954)to (3) thepeculiarmotionofclusteritself.For enclosed inparenthesesTableXII. the measuredV.Magnitudessodeterminedare + 1136km/secthemostuncertainofgroup choice eitheroftreatingthecorrelationmwith separately, orofsuitablycombiningthedatainto log czfortheist,3rd,5th,and10thnebulae ences intheluminosityfunctions forthevarious is tobepreferred,since it usesallavailable mean valuesofhighweight.Thelattermethod material andtendstosmooth anysmalldiffer- In analyzingthephotometricdatawehave © American Astronomical Society • Provided by theNASA Astrophysics Data System * Onsystemoffirstbrightest. Virgo Hercules Coma Perseus 0106-1536 2308+0720 2322 +1425 0705+3506 0138 +1840 0025+2223 0855+0321 0925+2044 1145+5559 1024 +1039 1520+2754 1239 +1852 1055+5702 1431+3146 Cluster (I) THE ASTRONOMICALJOURNAL •043 •035 .018 .065 .052 .044 .022 .004 •053 .072 .072 .078 •131 . 192 .159 .134 .202 .173 TABLE XIII.CORRECTEDPHOTOMETRICDATAFOR18CLUSTERS (2) AP(&) mag. .08 . 12 .00 .11 •95 .01 .00 .06 .01 .04 •05 . 10 •05 .02 .48 .24 . 12 .14 (3) K(z, to)p mag. (4) 08 02 25 21 20 33 33 SO 24 61 37 90 63 l6 IO 94 81 74 clusters. Themagnitudesofthe3rd,5th,and 0.48, 0.80,and1.29mag.respectivelyfromthe of theistbysubtractingmeandifferences The finalmagnitudes,Pc=P~AP(6)—Xp final datafordiscussionofthe[logcz,m~\relation values listedincolumns3,4,6and7ofTableXIII. umns 5and8ofthisTable.Theseconstitutethe nitudes, onthesystemoffirstbrightest,were tively fromtheVdata.Theresultingmeanmag- for theclusters. and V=—ÄV(b)Ky,arelistedincol- then correctedforlatitudeandKeffectbythe P data,and0.51,0.84,1.27mag.respec- has shownthat,inanexpandinguniverse,the 10th nebulaeweresystematicallyreducedtothat radiating attimehisgivenby intensity oflightreceivedattime¿0fromasource where Rqisthescalecoefficientinlineele- M\ =5\ogcz ertson (1955)as ment atthetimeofobservation¿0andaisrelated tion connectingmboiandzisthengivenbyRob- to thedimensionlessradialcoordinate.Therela- eter andXoisthesecondtimederivativeof Here, Ro/Ro=HistheHubbleredshiftparam- metric scalefactor,both evaluated atto-The c quantity ßisrelatedtothe timerateofchange the absolutebolometricmagnitude ofthenebu- ho Interpretation ofClusterData.Robertson(1938) 15-71 14.78 I4.I2 12.84 12.51 15.88 15.21 15.O4 15-93 15.22 16.26 I7.3I I7.3I 17-39 17.54 17.16 17.84 mag. 9.16 Pc* (5) + 1.086I-2ijl)zconst.(3) ¿boln — / RqRq\ AV (b) mag. .06 .09 .01 .04 .01 •03 .08 .00 .68 .00 .04 .01 •35 . 10 .04 .07 .09 (6) .17 2r2 47rRoo(l +s) Tbol K(Z, to)y mag. .09 .05 . IO .08 .04 .OI .17 •IS . 12 . 12 .17 •35 .18 .36 •44 •54 .48 (7) .58 (¿i) I3.O9 II.80 II.72 14. l8 I3.79 14-45 14.70 14.89 16.21 15.46 14.96 14.19 16.22 16.28 I6.4I 16.49 16.70 mag. 8.27 v* c (8) 147 (2) O'! V" 1956AJ. X correction duetotheStebbins-Whitfordeffect, These dispersions,arealsogiveninthisTable. in eachcasemaybejudgedbythedispersionsof analyzed intheformme=Alogcz+BzD lae, plustherateofchangethatpartK vides littleevidenceforthe existenceofpatchy Case ifitsthedatabest.SolutionsinCases2and in thelight-traveltimefornearbyanddistant and plustheeffectofanyintergalacticobscura- dispersion do:(1)intheabsolutemag- the distributionsofmagnituderesiduals. tion. Thisequationaccountsforthedifference velocity dispersionandtothemeanpeculiar Case 2isadoptedinthefollowingdiscussion. and towithintheprobableerrorforCase3. since inthemH=5byassumptionforCase2 made for3cases:(1)A,B,andDweretreated for bothPcandVc-Least-squaressolutionswere “world map.” clusters, byreducingthe“worldpicture”to 148 motions oftheclustersthemselves(cr);(3)scat- 3 aretheonlyonescompatiblewithequation(3), as unknowns,(2)Awasconsideredtobepre- observed doof0.32mag.iscompoundedthese tion inthedirectionof18clusters(o>); ter duetopossiblepatchyinternebularobscura- nitudes ofthenebulaeconsidered(ctm);(2)scat- cisely 5,withBandDasunknowns,(3)A ter intheredshiftcoordinateduetointernal Table XIVgivestheresults.Thegoodnessoffit be verysmall.Inparticular,thisanalysispro- four separatedispersions.Theremarkablesmall- and Dwereconsideredunknowns,withB=o. ness ofdoshowsthatvm,o’z,vf,anddmusteach internebular absorptionin the directionof18 Unknown (z, h)—Ky(z,>K?(z,/o)to)and B fromSolution2isonlytwiceitsprobableerror, describes deviationsfromlinearity.Thevalueof detected bystudyofthedispersions. hence that>bKy/U.Sinee¿xhastheform enters ¡xbythetermôK/ôt.Theexcessreddening Appendix B.ThedifferencebetweenK(z,t\)and but twouncertainelementsnotallowedforin since onlydeviationsfromuniformitycanbe obscuration iscontainedinthepresentmaterial, for (Tpbutthetruevalueisundoubtedlysmaller. clusters. Anupperlimitof0.30mag.isplaced of theStebbins-Whitfordeffectrequiresthat difference, whenexpressedinaTaylorseries, K(z,to) isabsorbedin¡xofequation(3).This inequality isB>By,asactuallyobserved. value larger.Thattheapertureeffectisindeed the apertureeffectinfaintclusters,and the datashouldbeemphasized.Theseare:(1) No informationonpossibleuniforminternebular years. SinceKandFarefunctionsofwave velocity oflight,c,isinlightyearsperyear,then equation (3)showsthattheconsequenceofthis distance. IfH~isexpressedin10yearsandthe nebular absorptionexpressedasFmag.perunit Here K=ôK/ôtandF(\)isanypossibleinter- applied isK(z,t\)insteadof¿)asgivenin negative signofB,buttheymakeitsabsolute Corrections forbotheffectsnotonlypreservethe of Bonwavelengthisclear. as wellofredshift.Thecorrectvaluetobe Appendix Barethosewhichwouldbevalidin due tothesmalleraperturecorrectionrequired present maybeseenbyseparateanalysisofthe length, thereasonforobserveddependence Whitford effect.ThecomputedKcorrectionsin negative Bisfoundwiththe10thrankednebulae, nebulae withthedataofTableXII.Alarger to stellarevolution,Kwillbeafunctionoftime caused inthefollowingwaybyStebbins- graphic andphotovisualsolutionsisundoubtedly difference intheBvaluesbetweenphoto- for thehigher-rankedclustermembers. F mustbeexpressedasmagnitudesper10light the absenceofSWeffect.Ifthiseffectisdue the solidlinesdrawnfromSolutions2.The [log cz,m~]relationfortheistand10thbrightest (Robertson 1955) F (2) possibleuniforminternebularobscuration. 0 The termofgreatestinterestisB,becauseit The dataareplottedinFigures13and14with We arenowinapositionto considertheresults 1 ¡X =046IM-K(X)cF(\)~]H~,(4) O'! V" 1956AJ. X been correctedonlyforthelatitudeeffectandselec- of nebulae.Theapparentphotographicmagnitudeshave corrections arenotincludedinthedatabutintroduced tive effectoftheredshift.The“energy”and“number” five majorconclusions. contained inthe[logcz,ni]relationsofFigures into thetheoreticalequationsusedforinterpretation. 1956 AprilTHEASTRONOMICALJOURNAL149 of thedetermination.Thisconclusionrestsupon for Case2withtheslopeassumedtobe5,and for smallzisascloseto5theprobableerrors relation islinear,onthesuppositionthatthere result meansthatforsmallz,theredshift-distance 5.029 zb0.121and4.9250.138forCase3.This amount tocancelthenon-linearityofredshift nebular absorption,theredshift-distancerelation postulate theexistenceofgeneraluniforminter- is nogeneralinternebularobscuration.Ifwe 13 and14.Thismaterialsuggeststhefollowing mag. perunitdistance,mustbeofjusttheright is non-linear.Theabsorption,expressedasF law sothattheobserved[logcz,m]relationre- unlikely butcannotdefinitelybeexcluded. mains linear.Suchaninterpretationishighly since noseparationofpointsoccursbetweenthe southern clusters.Thisisastrongertestthan (a) thesmallmagnituderesidualsofsolution that forthefieldnebulae,sinceclusterdata mean correlationline. (b) thedirectdeterminationofslopeas selection and(2)showsmaller scatteraboutthe 12 clustersinnorthgalacticlatitudesandthe6 (1) probablyarelessaffected byobservational Figure 13.Theredshift-Pmagnituderelationforclusters (1) Theslopeofthe[logcz,m]correlationline (2) Theexpansionappearstobeisotropic, © American Astronomical Society • Provided by theNASA Astrophysics Data System clusters istransferredtoFigure10forthefield nebulae inclustersisnearlyequaltothevery These values,togetherwithequation(3),give data and—2.2forthephotographicifan is seenifthelinedrawninFigure13for brightest ofthefieldnebulae.Thisnearequality 0.20 mag.atthedistanceofHydracluster. allowance ismadeforanaperturecorrectionof significant. Itsvalueis—3.0forthephotovisual law isnegativeandappearstobestatistically brightest clustermembers. few fieldnebulaeoccur.Onthisbasisthereap- nebulae. Suchalinedefineslimitabovewhich postulated intergalacticobscurationmustbedis- pears tobeanupperlimittheabsolutemagni- tributed with0.30>(Tp^omag. tude ofextragalacticnebulaeclosetothatthe where thesubscriptsPandVstandforphoto- graphic andphotovisualwavelengths.If2jup> expansion isaccelerating;otherwiseitdecel- erating. Foradecisionwe mustevaluatethe right memberofequation (4) whichinvolvesM 3.0 orif2fjiy>3.7,thenRispositiveandthe and Kastheprincipalunknown quantities. 0 (3) Theabsolutemagnitudeofthebrightest (5) Thesecond-orderterm,B,intheredshift (4) Thedeparturesfromuniformityforany Figure 14.Sameas13forphotovisualmagnitudes. =82 ^-° =-(3-7±0.8)+2mv(6) “Tyr “(3-°°-)+Mp(5) IbQ O'! V" 1956AJ. X 9 9 9 9 9 systems ofPopulationII.Currentideasforsuch appeal tosometheoryofstellarevolutionfor evolution stemprimarilyfromtheworkofM. Schwarzschild thathasappearedinaseriesof 150 cluster M3(Sandage1954b)providesabasisfor schild 1952;SandageandSchwarzschild papers withhiscollaborators(OkeandSchwarz- Härm andSchwarzschild1955).Applicationof an estimateofM.Withintheframeworkthis these ideastotheparticularcaseofglobular The changeintheabsolutemagnitudeof nosities arehomologous,i.e.parallelinthelog7V evolutionary tracksforthepresenttimeto-If stars wereformedabout5X10yearsago.The theory, theobservationaldatashowthatM3 for smallto/ti, years, allstarsbrighterthanabsolutebolometric giant region,andsubsequently,afterburning cluster havemovedfromtheiroriginalplaceson sequence. Weknowwithsomecertaintyonlythe theory predictsthatthebrighteststarsin 4 X10yr.andwiththeratioSfTlo/SflHobtainedby where 3TCoandaretherespectivemassesof main-sequence break-offpointintimehtois, Mhoi plane,anevaluationofMcanbemade. we assumethattracksforslightlydifferentlumi- magnitude +3.5haveevolvedfromthemain bright stars.Intheavailabletimeof5X10 in earlytimesbecauseofthepresencethese luminosities. Presumably,theclusterwasbrighter most oftheirfuel,havedisappearedtofaint last onebillionyears.If¿0=5X10yr.,ti the mainsequenceinH-Rdiagraminto brighter thanMo\=+3-5-Ifanappreciable assume thatmostofthelightcomesfromstars this changeinthebolometricmagnitude the starsatbreakpoint.Wewishtocompute gives, therefore,anupperlimittoM.Ifthecase fraction ofthetotallightcomesfromstarsfainter bolometric magnitudeoftheentireclusterifwe tracks thisvaluealsoequalsthechangeof iteration fromthemass-luminositylaw,then for ellipticalnebulaeissimilartothatofthe than Mboi=+3-5,thentheAMboiforsys- globular clusters,thenM^0.3mag.per10yr. tem willbelessthan0.3mag.Thiscomputation AAfboi =0.31mag.Forhomologousevolutionary ford’s currentsix-colorwork withthe200-inchin be madeonthebasisofhis statement(Whitford these distantclusters.Meanwhile, estimatesmay Precise valuesmustawaittheresultsofWhit- h Estimates ofMcan,atpresent,comeonlyby Estimates ofitandKyaremoredifficult. P © American Astronomical Society • Provided by theNASA Astrophysics Data System Aikfboi =2.5log+to/h(7) THE ASTRONOMICALJOURNAL 9 I 9 l9 92 9 2 arise fromadditionalradiationinthedistant systems ofaqualitylikethatTypeIGo supergiant.” Anenergycurvedeterminedfrom bins andWhitford1945)permitteddirectcom- and fromtheI(A)forsupergiantGostars(Steb- the J(X)forM32(StebbinsandWhitford1945) putation ofK{z,¿1)bytheproceduredescribed Whitford excessofif—Ky=+0.40mag.for and Ky~0.0mag.per10yr.Thesevalues in AppendixB,withtheresultthatit~+0.3 953) that‘Theobservedtwo-colorexcesscould agree fairlywellwiththeobservedStebbins- £^==1.086^1+-^- gives 2/¿=5.0[0.3—0.3F]and2/xy5-° the HydraCluster(Whitford1954). fying equations(3)and(4),nowbecomes for thesecondordertermB,obtainedbymodi- yr. andFinmag.per10l.y.,thenequation(4) tudes. Calltheseerrorseandey.Theexpression are the[logcz,m~]pairs.Oftwo,observa- about —5. even morenegativevalue.Forassmallavalue eral internebularobscurationwillgiveFan 2fxy =1.5.Equations(5)and(6)thengive in AppendixC,weadoptH~=5.4X10years. the redshiftparameterH.Fromdiscussion tional errorsareappreciableonlyinthemagni- the uncertaintiesateachpoint.Thebasicdata review thestepsinitsevaluationandtoindicate as F=0.30mag.periol.y.,R0R0/R0becomes for Vmagnitudes.Theaverageis—2.6.It tant cosmologicalimplicationsthatitiswellto interesting tonotethatthepresenceofanygen- must hold.Withj5/i.086—2.0andFy/i.o86 If theunitsofMandKareinmag.per10 M =+0.3,ifandKyo,equation [0.3 +0.0—Fy~].IfF=o,then2^and P P I.OoO the faintclusterswiths « 0.20mustthenbe P P 0 (RoRo/Rn) ——3.0forPmagnitudesand—2.2 P p P (9) requiresthat|e/s|^ 3.0mag.and\ey/z\ P ^ 2.2mag.Theerrorsin themagnitudesof ^ —2.7,asgivenbytheobservations,andwith P The resultthatRoisnegativehassuchimpor- Finally, toevaluate2/xweneedthevalueof If werequirethatRo^o,thentheinequality - i+5-o(Mitp.vA,y) — 5.0(ilïi?vFy)+e,y/s:J(8) P)P r R0R0 — €V/S^O(9) P( 61, No.1237 O'! V" 1956AJ. X 9 9 9 9 9 These modelsshowhowthefunctionR(t)de- of generalrelativity,aseriesmathematical data, suchastatementcannotbegivenatpresent cosmological modelsconsistentwiththepresent constant A.Threeofthecrucialobservational for thefollowingreason.Withfieldequations sign ofÍ¿owithsomeconfidence. according tothesignofspacecurvature pends ontime,andtheydifferfromoneanother pansion. (See,e.g.,Einstein1945orBondi1952.) models areobtainedforthecharacterofex- paper withadefinitestatementofthepossible work anduntilanadequatetheoryisworkedout K requirethatÍ¿benegativeandtheex- Ro tobepositive.Withthemorerealisticvalue are (1)thesignofRo,(2)valuei/H,and items requiredforachoicebetweenthemodels be possibletoestimatethevalueofMand excess reddeningisatimeeffect,suchtheory considered asestablished,however,untilaccurate as toappearimprobable. of ifp=+0.3mag./ioyr.,theupperlimitto large. IfK?=o,thenM^0.6mag./ioyr.for for theageofoldeststars orfromageological universe’’—really thetime sincethebeginningof time ofthespectralenergycurves.Thenitshould must predictfromevolutionarytracksinthe values ofKareavailablefromWhitford’scurrent any reasonableestimatesoftheerrorsin rect ornon-applicabletothepresentcase,and on stellarevolutionmayprovetobeeitherincor- the expansion—fromsayan astrophysicaltheory Tfboi, logTplanethedetailsofchangewith pansion isdecelerating.Thisresultcannotbe measured magnitudesandinthevaluesofM nevertheless M—0.9mag./ioyr.issohigh that M^0.3mag./ioyr.maybeinvalidated, M becomes+0.9mag./10yr.Thesevaluesseem upper limittoMthatsatisfiesequation(9)is to explaintheStebbins-Whitfordeffect.If therefore thatthebasisofourpresentestimate tion. Whileitisobviouslytruethatpresentideas quite highonanycurrenttheoryofstellarevolu- is anexcessreddeningandnotabluing,the that itp>obecausetheStebbins-Whitfordeffect observational uncertainty. tion (8)withoppositesign,andsinceweknow sign ofRo.Since,however,MandKenterequa- values probablyaretoolargetobeascribed 0 (3) independentknowledge ofthe“age (1, o,—1)andofthevaluecosmological 1956 April e I cpJ^0.6mag.and|ey|0.4These Although itwouldbeappropriatetoendthis The foregoinganalysisthereforesuggeststhat Incorrect estimatesofMandKalsoaffectthe © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL difficulty, becausemeasureshaveusuallybeen revealed byvisualinspectionofwell-exposed eters ofnebulaeareverymuchlargerthan APPENDIX A.CORRECTIONSTOTHEMAGNITUDES etry, asystematicerrorinthemagnitudesis depend upontheapertureusedinphotom- restricted totheregionsofnebulaeseenon nebular magnitudeshavebeenaffectedbythis photographs. Nearlyallearlyinvestigationsof of thelargeangularsizeregionscontrib- obtained. changing theslopeofregressionlinered- eter itself.Thissystematicerrorhastheeffectof photographs. Becausetheobservedmagnitudes is difficulttomeasurebyanytechniquebecause before numericalresultsfrom thecorrelationsare removed fromthebasic magnitude measures shift vs.apparentmagnitude. Theerrormustbe introduced thatdependsuponthenebulardiam- uting appreciablytothetotallight.Thediam- reading ofanearlydraftPartIII. fine jobinpreparingthelinedrawingsfor acknowledged. Mr.HaroldKinneydidhisusual extensive reductiontoastandardsystemofwave press. ItisalsoapleasuretothankDrs.H.P. ful acknowledgmentismadetoMrs.C.Roger lengths, andtoMrs.HowardC.Cowan,whodid Lynds (BeverlyTurner),whocarriedoutthe appreciated. Wilma Berkebile,whosecontributionsaregreatly Robertson andA.E.Whitfordfortheircritical C.I.T. andhisveryefficienthelpisgratefully Part IIIwasdonebyMr.WalterBonsackof typewriter. the exactingjoboftypingonIBMelectric has participatedinthemeasurementandreduc- preparation ofthiscompletepaper;andalsoto sincere appreciationtoMissAliceBeach,who tion oftheplatesand,toalargeextent,in mar listsofredshiftsitisapleasuretoexpress time. such adiscussioninappropriateatthepresent anticipated resultsforcomputingK(z,h)make Mrs. MaryCoffeen,MissSylviaBurd,and rediscussion ofthesignÍ¿withWhitford’s uncertainty inthevalueofi/i7andimminent known, aweedingoutofcertaininconsistent age fortheearth.Whenthesethreeitemsare models canbemade.Unfortunately,thepresent 0 The totalmagnitudeofanextragalacticnebula Acknowledgments. FortheMountWilson-Palo- Part oftheextensivecomputationalwork For theLicklistofredshifts(TableV),grate- FOR APERTUREEFFECT 151 O'! V" 1956AJ. X 2 2 -2 ra = conclusion resultsfromextrapolationofHubble’s for expectingtheinterpolationequationtohold. intensity obtainedbyusingthisformisadiver- estimated fromaphotograph. only tor/a=20.Tothispointhisequationfits ures thatHubbleconsideredreliableweretaken gent integralandconsequentlythetotallightof r/a. Sincetheradialintensitygivenbythisequa- interpolation formula/=/[(r/a)+1Jtolarge that suchalimitingmagnitudedoesnotexist.This knowledge oftheformasymptoticap- known forr¡a>50,wedonothavesufficient diameter ofthenebula.Thedeterminationthis ford’s catalogueswillbeafunctionoftheratio the datawell.Beyondr/a=30thereisnoreason any givennebulawouldnotbefinite.Themeas- tion doesnotfallmorerapidlythanr~,thetotal proach. Someinvestigatorshaveeveninferred ing ofthemagnitudeapproachedasymptotically Whitford, Disthediameterofdiaphragm where risthedistancemeasuredalongmajor of theapertureactuallyusedtoangular magnitudes inPettit’sandStebbinsWhit- same conclusion.HismeasuresforNGC3379ex- has alsostudiedtheproblemandreaches more rapidlythanr.G.deVaucouleurs(1948) that beyondr/a=20theobserved/(r/a)falls as r/a—>00.SincetheformofI(r/a)isnotyet reason. Thetermtotalmagnitudehasthemean- correct thecataloguemagnitudeseither(1)to catalogue valuesofPettitandStebbins axis ofthenebulaandaisvaluerat distribution inellipticalnebulaeshowedthere- function isthemainobjectiveofthisappendix. nitude withinagivenisophote,forthefollowing desired quantitywouldbethetotalmagnitude, contained withinacertainisophote.Ideallythe used bytheseobservers,andDisthediameter where Amisthecorrectiontobeapplied studied. Hubblefurthershowedthattheisopho- I =/0/4,isverynearlythesamefor15nebulae markable factthattheintensityfunctionI(r/a), I 5°reachedbyDennison. FortheE2neb- tend onlytor/a=22which isnotasfar but thisismoredifficulttoobtainthanthemag- tion ofthecorrectionfunctionAm=/(DD) tal contoursareelliptical.Thesetworesults University ofMichigan1954)NGC3379shows together withtheformofI(r/a)permitaderiva- 152 the totallightofnebula,or(2)to ula NGC4649,deVaucouleurs hascarriedhis Indeed, E.Dennison’srecentphotometry(Thesis, 0 p a r>a1 The functionAmcouldbedefinedsoasto It isclearthatthecorrectionstotabulated Hubble’s (1930)investigationoftheintensity © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL61,No.1237 2 23 tion Awwillbederivedtogivethemagnitude de Vaucouleurs’results.Beyondthispoint,Den- r/a =20isgood.Similaragreementexistswith contained withinsomestandardisophote. Figure Ai.TheradialintensityfunctionI{r/a)fortheEo NGC 3379asafunctionofthe measuringaperture.The those ofHubbleinFigureAi.Theagreementto r/a =50,avaluefortheasymptoticmagnitude present lackofknowledge/(r/a)beyond probably doesexist.However,inviewofthe corresponds tor/a=26.Hefindsthat/(r/a) nison measureslowerintensitiesthanHubble, is notreliable.Consequentlythecorrectionfunc- 20. Anasymptotictotalmagnitudetherefore decline issteeperthanr~andthisagreeswith goes approximatelyasr~-forthisobject.The measures tor=190"alongthemajoraxiswhich I {r/a)functionofFigureAiis adopted. Dennison’s measuresinNGC3379beyondr/a— Figure A2.Theincreaseinthe apparentmagnitudeof Dennison’s resultsareshowntogetherwith nebula NGC3379asgivenbyDennison(1954). O'! V" 1956AJ. X tained from pared withtheAwcorrections. introduced bythisassumptionaresmallcom- assumed tobelikethatinEnebulae.Theerrors of Dennison’s/(r)andforthecaseHubble’s on aperturefortheEonebulaNGC3379isob- elliptical inoutline.Thisdiskcontributeseighty calibration) ofDennison’s/(r/a)functionapplies but thelatterconsideredhisownphotometry The [w,r]relationofFigureA2permitsthe Figure A2showsthecurves[w,rjforcase per centormoretothetotallight(Holmberg assume thattheshape(butnotnecessarily son’s I{r/a)isadoptedasstandard. beyond r/a=20assomewhatuncertain.The nitude whichwouldhavebeenmeasuredifthe reduction ofmeasuredmagnitudestothatmag- formula extrapolatedtolarger.Thisfigureshows structure ispresentinallnebulartypesand of PopulationIIstarswhichunderliesthespiral shapes ofthe/(r/a)curvesfor15Enebulae per squaresecondofarc.Inthesequel,Denni- unit ofintensityinFigureAiis27magnitudes that, exceptfortheScandIrrnebulae,disk studied werenearlyidenticaland(2)inthefact tion liesin(1)Hubble’sdemonstrationthatthe apparent ellipticitiesofprojected imagesasafunctionof totic magnitudeevenfromDennison’sfunction. the difficultyofobtainingvalueasymp- to allnebulae.Thejustificationforthisassump- 1956 April the ratioofmeasuringaperture totheapparentnebular diameter. 1950). Therefore/(r/a)forSotoSbnebulaeis Figure A3.Themagnitudecorrection curvesfordifferent To obtainageneralformforAwweshall The dependenceofthemeasuredmagnitude w(r) =const—2.5logI27rr/(r)Zr(A.l) © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL 0 aperture hadbeenacertainstandardsize.We size. must nowdecidewhattouseasthisstandard graphic platesappeartohavedefiniteboundaries. While itistruethattheapparentdiametersbe- come largeronplatesoflongerexposuretimes, conditions ontheplate.Holmberg(1945)has means thatthelimitofvisualdiscrimination conditions showthesamediameters.Thisfact it isalsotruethatplatestakenunderidentical at somedefiniteisophoterelatedtotheexposure available, itisclearthatahomogeneoussetof measured inlinearunitsontheplate(saymm). pends uponthegradientof/withrwhereis shown thatthelimitofdiscriminationalsode- isophotic diameterscouldbeobtained.Aclose is smallandneglectedinwhatfollows. between anebulaandtheskybackgroundoccurs define thestandardisophoteasthatpointin Wtotai- Forthepurposesofthispaperweshall on theaverage,thanlightofnightsky. every carehasbeentakenforuniformity.With approach tosuchaplatecollectionexistsinthe Fortunately thiseffectonthefinalAwfunction 48-inch Schmidtplates.Thevalueof2.5Dis of 2.5timesthemaximumradiusvisibleon magnitudes willbecorrectedmaychosenarbi- square second,whichisabout0.6mag.fainter, at thispoint.Thisisophoteis22.6mag.per or r/a—12.9.FigureAishowsthatlog/=1.74 diameters. Thediameteroftheapparentimage plates takenwiththe48-inchSchmidtfor r/a =32.4.ThecalibrationofFigureAishows so thatthecorrectedmagnitudewillbecloseto inspection willapproachasystemofisophotic nebula thathasaradialdistancefromthenucleus trarily, but,forconvenience,itshouldbechosen NGC 3379ontheseSchmidtplatesis2r—121", these plates,thediameterZ)obtainedbyvisual Palomar-National GeographicSkySurvey,since about 25.1mag./sq.sec. 302" inNGC3379andthisfigurecorrespondsto that thisisophotehasasurfacebrightnessof with anaperturewhoseradiusdifferedfrom from FigureA2.IfNGC3379weremeasured r =151",thecorrectionAwmustbeappliedto now permitsthecalculationofAw=f{D/2.$D/) The valuesforAwmay be computedforany have beenmeasuredwith an apertureof2.5D. value ofr/151fromFigure A2byassigning the measuredvaluetogivethatwhichwould s s v a Images ofmostextragalacticnebulaeonphoto- The standardisophotetowhichthecatalogue If astrictlyhomogeneoussetofplateswere The choiceofthestandarddiameter2.5Z> s 153 X O'!V"

1 154 THE ASTRONOMICAL JOURNAL 61, No. 1237

2 Am — o at r = 151". The Am function is plotted logue magnitudes to give the magnitude corrected S in Figure A3 as the correction curve for nebulae for aperture effect. In many cases the validity of ^ with ellipticities e = o. The curves for nebulae the corrections could be tested from Pettit’s cata- with ellipticities 3, 5, and 7 were obtained in the logue, since two or more apertures were frequently following manner. The intensity at every point used on a given object. This permitted two or of each elliptical image was obtained by assuming more independent determinations of the corrected that the I(r/a) function of Figure Ai applies m. Surprisingly consistent values were obtained. along the major axis and that the isophotes are Often the agreement was within ±0.1 mag. The elliptical. Numerical integration for the intensity corrected magnitudes for every object used in within circular apertures placed upon the ellip- the field-nebulae correlations are given in Table tical images gave the [m, r~] curves similar to the Ai of this appendix. Magnitudes for individual curve in Figure A2 for the Eo case of NGC 3379. members of the two great clusters in Virgo and The correction curves [Am, Dv/2.$ for each Coma are also included in the table. ellipticity derived from the [m, r~] curves are also The success which has been achieved in re- shown in Figure A3. moving the aperture effect from the magnitudes Every nebula for which either Pettit or Steb- may be determined by study of the overlap be- bins and Whitford have a magnitude and for tween the catalogues of Pettit and of Stebbins which a redshift exists was examined on the 48- and Whitford. These lists have 79 nebulae in inch Schmidt plates to obtain the diameter Da common for which redshifts are available. Of and the ellipticity of the projected image. Pettit these, 44 have color indices in common. After as well as Stebbins and Whitford give the aper- correction for the aperture effect, the mean re- ture Dv to which their magnitude corresponds. sidual in magnitude in the sense SW minus Pettit Consequently Dv/2.$ Da was found for each ob- is AP = +0.026 mag. The dispersion of the dis- ject and Am was read from the appropriate curve tribution is o- = 0.191 mag. The lack of sys- in Figure A3. This value was applied to the cata- tematic difference and the relatively small size of the random difference shows that, for the pur- poses of this paper, the two basic catalogues may be used interchangeably. Figure A4 shows the distribution of AP between the two lists. Comparison for color differences of the 44 ob- jects common to Pettit’s and to Stebbins and Whitford’s catalogues reveals the existence of a color equation. This result was expected, since Pettit’s measures were not reduced to a standard system but were left on his natural instrumental system. A least-squares solution of the data gives

(Cl)pettit = 0.018 + 1.056 (CI)sw- ± 0.027 ± 0.033

Comparison of Pettit’s magnitudes, corrected for aperture effect, with magnitudes determined by Holmberg is also possible. For the past several years Holmberg has been measuring the colors and magnitudes of bright nebulae by a laborious but highly accurate photographic method. His final catalogue, based on plates taken with the Mount Wilson 60-inch and 100-inch telescopes, will contain between 250 and 300 nebulae. By private communication Holmberg states that the mean error of his final magnitudes for objects measured to date (1955) is ±0.04 mag. and the mean error of the final color is ±0.05 mag. Figure A4. Histogram of the distribution of magnitude differences between Stebbins-Whitford’s and Pettit's cor- Holmberg also states that comparison of his mag- rected catalogues. nitudes with those of Stebbins and Whitford

© American Astronomical Society • Provided by the NASA Astrophysics Data System O'! V" 1956AJ. X 1956 April 1727* 12.31569 Note (7)18.41097 Note (6)19.91087 Note (4)15.8936 Note (5)16.91023 Note (2)19.4908 7814 11.7751 Note (3)16.2925 Note (1)15.9877 NGC m 578 11.61449 628 9.81518 596 12.11453 584 11.41451 564 13.81441 560 14.01439 672 11.41600 520 12.21407 681 12.81601 636 12.41587 524 11.61426 514 12.31404 718 12.5Note(9) 507 12.81400 499 13.21399 750 13.71700 741 13.0391* 736 13.61640 720 11.31637 pg 495 14.21398 488 11.41395 474 13.01385 428 11.81380 404 11.41359 388 15.61332 386 15.71331 385 14.31317 384 14.61316 383 13.61302 380 14.01300 379 14.01232 375 15.91209 357 13.01201 255 12.41140 278 11.51156 214 12.81073 227 13.51084 210 11.81068 194 13.31058 182 13.41052 160 13.71003 157 11.0Note(8) 128 12.7972 69 15.9821 71 14.8864 83 14.3891 80 13.9890 72 14.7871 68 14.6788 23 13.0772 16 13.2753 © American Astronomical Society • Provided by theNASA Astrophysics Data System TABLE A1.MAGNITUDESFOR576NEBULAECORRECTEDAPERTUREEFFECT* THE ASTRONOMICALJOURNAL (12.1) 261310.9 (10.0) 260812.8 13.9 269415.5 12.4 277511.3 12.6 268512.3 14.9 263312.8 14.5 271511.9 12.9 269313.3 11.2 268310.4 11.1 268111.0 12.3 267314.4 11.2 267213.2 11.5 264613.1 12.1 278212.5 12.2 274413.8 12.9 271612.7 14.6 271212.8 10.4 265510.8 11.4 265412.8 12.5 2642(14.0) 12.9 183212.0 12.9 277611.9 11.6 276811.0 15.1 274913.5 13.2 273212.7 11.7 Note(12)20.3 12.3 Note(11)19.2 11.0 2389*13.9 11.0 263912.6 11.2 256214.0 14.1 221711.8 12.0 213911.9 12.4 196411.4 11.2 188914.4 14. 1174412.1 15.1 274812.3 11.1 256313.7 11.7 253712.2 10.8 227612.0 12.4 226812.2 11.6 214611.3 10.5 255113.2 12.6 254912.1 12.2 253513.2 10.4 252512.0 10.1 237914.6 11.1 233611.2 10.8 230012.2 12.6 Note(10)17.1 12.8 253212.9 11.4 252312.6 11.1 250012.0 11.7 246012.9 11.9 24038.8 11.6 238913.3 12.1 236611.5 12.1 233912.5 10.5 231413.3 14.1 234713.1 9.9 244113.0 2880 12.63593 2831 14.83504 2811 12.43489 2798 13.03486 3310 10.84026 2855 12.63521 2832 13.53512 2787 11.73430 3348 12.04051 3344 10.44038-9 3338 (12.3)4036 3301 12.23998 3277 12.43992 3254 12.13990 3245 11.83962 3222 13.83945 3193 12.23941 2859 12.03556 2841 10.03516 3368 9.94111 3367 11.94106 3359 10.94105 3351 10.54102 3227 11.33953 3226 12.63949 3190 12.13923 3184 10.23900 3169 11.23898 3166 11.23893 2983 12.63623 2964 12.13611 2950 11.83610 2914 14.23608 2911 13.63607 2903 9.73605 2865 12.53585 3414 12.04151 3412 11.54150 3389 12.14143 3384 10.94138 3379 10.54125 3377 11.34116 3185 13.13904 3158 13.23872 3147 11.43818 3115 10.13810 3078 12.13726 3067 12.63684 3066 13.53681 3065 12.93675 3055 12.63665 3032 12.83646 3031 7.83642 3003 12.03640 2985 11.23626 2976 10.93619 2974 11.93613 3077 10.93686 2986 12.23627 Note (.13)18.04179 NGC m pg (12.4) 457812.3 (12.0) 457011.8 12.0 419210.5 11.6 421611.1 10.7 420311.5 11.0 421410.2 12.7 424410.3 12.9 422012.2 11.6 42589.0 11.0 425410.2 10.4 425111.6 11.0 427410.8 14.0 427312.2 11.9 428112.3 12.1 427811.2 12.6 430310.0 11.8 429112.4 12.8 428313.1 11.6 4394 11.6 437410.5 11.0 435011.9 12.5 442513.2 10.7 442111.8 11.9 441410.9 11.0 445911.5 11.7 4435 12.3 442910.9 11.8 440610.3 11.9 449213.2 11.3 447812.3 11.3 447711.4 11.7 446112.0 13.0 44499.8 13.0 444811.7 11.1 444211.4 11.8 443811.2 11.2 452711.4 13.6 449410.9 10.7 449010.0 12.1 447412.7 12.4 447311.3 12.3 456910.5 11.0 4552 10.8 455012.6 11.6 454810.9 11.7 454611.4 10.5 452610.6 11.3 Note(14)15.4 11.7 447913.6 10.9 462111.0 12.5 45949.1 11.6 458912.0 mp NGCm 12.6 463812.2 12.0 463610.6 12.4 46319.6 11.7 46499.9 11.2 464712.1 9.6 424512.3 gpg 9.5 436510.9 9.9 431411.5 155 X O'!V"

156 THE ASTRONOMICAL JOURNAL 61, No. 1237

C) TABLE AK MAGNITUDES FOR 576 NEBULAE CORRECTED FOR APERTURE EFFECT. NGC NGC NGC NGC NGC m NGC m P9 P9 "'pg pg pg pg 4660 12.1 4902 11.7 5474 12.1 5898 12.6 6814 12.2 7392 12.6 4666 11.5 4907 14.7 5485 12.6 5899 12.5 6824 12.9 1460* 15.3 4697 10.4 4908 15.1 5493 12.5 5903 12.7 1317* 14.5 7448 12.0 4698 11.6 4045* 15.4 5533 12.7 5907 11.0 6921 14.7 7457 12.3 4699 10.2 4051* 14.8 5548 12.8 5921 11.6 6927 15.6 7469 12.7 4725 10.0 4911 13.6 5557 12.3 5962 12. 1 6928 13.8 7479 11.6 4736 8.7 4915 13.0 5566 11.4 5970 12.2 6930 14.0 7499 15.1 4742 12.5 4921 13.6 5574 13.4 5982 12.4 6944 14.4 7501 15.5 4753 10.7 4941 12.0 5576 12.0 5985 11.9 6946 9.8 7503 14.7 4754 11.6 4958 11.5 5585 11.5 6015 11.6 6951 12.5 7507 11.6 4762 11.0 4995 11.9 5614 12.5 6027d 14.8 6954 14. 1 7541 12.6 4789 13.3 5005 10.6 5631 12.6 1183* 15.8 6962 12.8 7562 12.9 4793 12.3 5018 12.2 5633 12.9 1185* 14.8 6963 15.2 7576 13.8 HZ46 15.2 5033 (10.6) 5638 12.4 1194* 15.4 6964 14.2 7585 12.7 4800 12.2 5049 13.8 5668 12.2 6070 12.3 7137 13. 1 7600 13.0 4814 12.7 5055 9.0 5672 14. 1 6181 12.3 Note (17) 15.4 7606 11.6 4826 9.2 5077 12.6 5676 11.7 6207 12.0 Note (18) 16.2 7611 13.6 4850 15.4 5087 12.1 5687 12.8 6217 11.9 Note (19) 16.5 7617 15.0 3946* 15.3 5173 13.8 5689 12.9 6239 12.9 7171 13. 1 7619 12.4 4853 14.5 5194 8.6 5713 11.8 6314 14.0 7177 12.0 7623 14.0 4856 11.4 5195 (10.7) 5746 11.3 6340 12.0 7217 11.0 7625 13.2 4860 15.0 5198 13.0 5806 12.4 6359 13.8 7240 15.5 7626 12.7 4861 12.9 5204 11.7 5812 12.6 6384 11.4 7242 14.3 7640 11.7 4865 14.7 5248 11.0 5813 11.8 6412 12.4 7252 13. 1 7671 13.8 4866 12.0 5273 12.5 5820 13.1 6482 13.1 7302 13.1 7678 12.5 4867 15.7 5308 12.2 5831 12.6 6503 10.7 7314 11.6 7679 13.? 4869 15.0 5322 11.0 5838 11.9 6627 14.4 7317 15.3 7716 12.9 4872 15.4 5353 12.1 Note (15) 11.3 6635 14.7 7318a 14.8 7723 11.8 4874 13.7 5363 11.2 Note (16) 14.1 6643 11.8 7318b 14.9 7727 11.6 4881 14.8 5364 11.0 5850 11.8 6654 12.5 7319 13.7 7741 12.3 4886 15.2 5371 11.4 5854 12.6 6658 14.1 7331 10.2 7742 12.2 4889 12.9 5377 12.0 5857 13.9 6661 13.2 7332 11.7 7743 12.3 4021* 15.8 5394 13.6 5859 13.2 6674 13.0 7343 14.5 7769 12.5 4895 14.3 5448 12.2 5866 10.9 6702 14.0 7377 12.4 7770 14.5 4896 15.1 5457 8.5 5878 12.4 6703 12.5 7385 14. 1 7771 13.1 4900 11.9 5473 12.4 5879 11.9 6710 14.2 7386 14.6 7785 13.0

NOTES TO TABLE

(1) Anon, at 0016+2946. (11) Neb. No. 10 in foreground of Cl 0855 + 0321. (2) Neb. No. 9 In foreground of Cl 0025 +2223. (12) Neb. No. 11 in foreground of Cl 0855 + 0321. (3) Anon. M31 field at 0023 +4042. Mag. by Kron. (13) Neb. No. 1 in foreground of Cl 1055 + 5702. (4) Anon. M 31 field at 0026 +3914. Mag. by Kron. (14) Anon, at 1227+ 1247. (5) Baade “a11 M31 field. Spr ext I2/H2* Mag. by Kron. (15) Mag. Is for NGC 5846 plus anon, companion. (6) Anon, at 0047 + 4219. Mag. by Whitford and Code. (16) Mag. is for anon, companion to 5846. (7) Anon, at 0047 + 4220. Mag. by Whitford and Code. (17) Anon, at 2058 + 1607. (8) Anon, at 0234 + 3412. (18) Anon, at 2058 + 1556. (9) ’Anon. 0438 + 0409. (19) Anon, at 2059 + 1556. (10) Anon, at 0705 +3506 (Brightest member of Gemini Cluster). (1952), after applying a correction to the latter is of interest. Holmberg has generously made his for aperture effect, gives a distribution of resid- manuscript catalogue available for this compari- uals whose dispersion is about 0.10 mag. Since son. The distribution of differences, in the sense this dispersion is less than a = 0.19 mag. ob- Holmberg minus Pettit, is shown in Figure A5 tained from the foregoing comparison of Pettit’s for 56 nebulae in common. A normal error func- and of Stebbins and Whitford’s corrected mag- tion is drawn with AP = —0.04 mag. and a = nitudes, a direct comparison of Pettit’s corrected 0.189 mag. This comparison of Pettit’s values magnitudes with the precision data of Holmberg with Holmberg’s gives results which are almost

© American Astronomical Society • Provided by the NASA Astrophysics Data System 1956 April THE ASTRONOMICAL JOURNAL 157

certain properties of extragalactic nebulae, are available from observational astronomy. The first of these numbers is the redshift AA/Ao. It is directly obtained by spectroscopic observation. The second is the bolometric magnitude which, unfortunately, is not directly measured but which must be derived from observed heterochromatic magnitudes. The term to convert observed mag- nitudes to a bolometric scale is called K. Its evaluation is the subject of this appendix. The bolometric magnitude of a radiating body is defined as the total energy, expressed as a magnitude, received from all wave lengths on a unit area outside the earth’s atmosphere. Such a magnitude is never directly measured because of the selective spectral transmission of the at- mosphere and response of the detecting device. Hence, bolometric corrections must be computed from the known properties of the source, atmos- phere, and receiver. Evaluation of the K correc- tion is made by computing the difference of the bolometric corrections for nebulae with different AA/Ao. This difference is caused by the change in the heterochromatic energy received through the acceptance bands of the radiation detector due to the redshift of the nebular spectrum. Figure Aß. Same as A4 for Holmberg’s tabulated magnitudes minus Pettit’s corrected values. We shall first consider the idealized case where all nebulae of a given type with 3 = 0 have the identical with those of the comparison of Pettit same spectral energy curves, and where these with Stebbins and Whitford. However, the value curves do not change with time. This assumption of a = 0.10 mag. from the comparison between is known to be false from the existence of the Holmberg and Stebbins and Whitford shows that Stebbins-Whitford effect (1948), but we shall the accuracy of Pettit’s magnitudes is lower than later see how this idealized theory of the K correc- those of Holmberg or of Stebbins and Whitford, tion may be modified to fit actual conditions. because absolute magnitude of the ance bands of the receiver. Let /Z(A) be the nebulae themselves. The agreement of the com- energy-distribution function, outside the earth’s parison between the catalogues of Stebbins and atmosphere, for a nebula with redshift s, ^(A) the Whitford and of Pettit with the comparison be- sensitivity function of the atmosphere, telescope, tween those of Holmberg and of Pettit suggests and detecting device, h the observed heterochro- that the gross systematic aperture effect has been matic intensity of the nebula, and /boi the bolo- removed from the basic magnitudes. This con- metric intensity ; hence by definition clusion depends upon the assumption, however, that Holmberg’s data require no correction for /boi(X) = A I (X) dX, (Bi) the large limiting diameters reached in his pho- Z tometry.

lh(z) = A J/ S(\)I2(\) d\, (B2) APPENDIX B. THE K CORRECTION In the various theoretical treatments of the where A is a normalizing factor depending on the expanding universe it is customary to assume zero point of the magnitude scale. The bolo- that pairs of numbers, [2, mboi], characterizing metric correction Am(z) is defined by

© American Astronomical Society • Provided by the NASA Astrophysics Data System O'! V" 1956AJ. X 6 The differenceintheobservedheterochromatic interest. From(B), magnitudes duetotheredshiftisquantityof where 158 Since Aw(o),whichisthebolometriccorrection From (B)anditfollowsthat stant fromtheobservedmagnitudem^z)ifKis for zeroshift,isassumedconstantanygiven known. metric magnitudeisobtainedtowithinacon- and SÇk)areknown.Thesefunctionsobtained from (Bq)withtheaidof(Bi)and(B2),if/(X) nebular type,thisequationshowsthatthebolo- A Xiocm 3 3 2 The valueofKfordifferentzmaybecomputed 42 41 40 39 38 37 36 34 33 49 48 47 46 45 44 43 35 32 50 51 53 52 51 50 63 62 61 60 56 55 54 66 64 59 58 57 68 67 65 © American Astronomical Society • Provided by theNASA Astrophysics Data System TABLE BI.SENSITIVITYFUNCTIONS(X) WboiiV) —Am{6)=m^z)K,(B6) 4 .404 .402 .426 .44O .44I .42I •375 •SSI .293 •243 •I35 .028 .002 /boi(s) =/h(s)io°-^T(B) .163 .205 .249 .285 .3OO •319 .366 .408 .061 • HI .226 .269 •34I •384 .083 .III .I83 .OI6 .O27 .O42 .007 .OO9 .Oil .OO4 .005 .OO3 Free IO 3 K =Am(z)—(6). /h(s) /boi(2) 4(0) 4oi(o)’ =4Ä Pettit •354 •354 •392 •370 .003 . 170 •349 •378 .387 •SSI .015 .036 •095 . 129 .265 .310 .294 .258 .208 .114 .014 .OOO .000 .063 .217 Blue THE ASTRONOMICALJOURNAL61,No.1237 Yellow . I92 .220 .077 . IOI . I29 •ISS . 172 .210 .220 .152 .032 .000 .OI6 •057 •075 .008 .005 .009 .Oil .027 .042 .003 .004 .007 I.249 1-254 I.266 I .187 I .120 i. 148 1.050 1.239 Blue .964 .823 .009 .044 .069 •157 .627 .864 .008 .013 •245 •405 .638 .000 •442 • 155 .000 Stebbins and Whitford i .084 1.037 1.097 Yellow (B5) (B4) •455 .229 .008 •723 .962 .964 .056 .003 •405 .609 •875 .209 •305 .072 .165 •037 . IOI .000 .009 .019 as follows.StebbinsandWhitford’ssix-colorcurve since, accordingtotheseauthors,the/o(X)for taken asthestandard/o(X)forellipticalnebulae, sensitivity functionvS'(X)isfoundfromtheprod- for tworeflectionsfromaluminizedmirrors K =2.5log Stebbins andWhitford’s(1948)filtersplusphoto- uct of(1)thespectraltransmissionatmos- M2 isrepresentativeforthisnebulartype.The sity atXjiew=X(i+z).Withthisprocedureit simple quadrature,onceI(X)isknown.This determined withthejiggle-cameraat200- electric equipmentformagnitudesdeterminedin phere (Pettit1940),(2)thereflectioncoefficients intensity atagivenXandbyplottingthisinten- function isconstructedfrom/o(X)byreadingthe inch. Forjiggle-cameramagnitudesonlyonere- photographic platesplusfiltersformagnitudes this way,or(4)thesensitivityfunctionsfor /s(X), hasbeenartificiallyincreasedby1+z. is obviousthattheareaundernewcurve, compute K.Equations(B4)and(B2)give flection fromanaluminizedmirrorisinvolved, the sensitivityfunctionsforPettit’s(1954)or change inthecolorindex,A(P—V),dueto Consequently thefirsttermin(B7)is2.510g Table Bi.ThenormalizationofS(\)inthistable The adoptedsensitivityfunctionsarelistedin since photometryisdoneattheprimefocus,but K?(z) —Kv(z),anditis the colorchangepre- photographic (P)andphotovisual(V)magni- corrector lensentersinstead.However,sincethe the transmissionfunctionofRossf/3.67 dicted iftheassumptionsused inderivingKare redshift isalsogiven.Thisobtainedfrom tudes, K?(z)andKy(z),computedfromB7.The is arbitrary,sinceonlytheformrequiredto at the100-inchisusedforjiggle-cameracase. computed forStebbinsandWhitford’sequipment removal ofonealuminumreflectionandtheaddi- (1948) forM2,reducedtointensityunits,is true. Itisknownthatthispredicted colorchange (1+3). in thewave-lengthregionsconsidered,S(\) tion oftheglasstransmissionnearlycompensate 3 Z (Pettit, reportedbySearesI94),andeither( 3 3 The secondtermof(B7)maybecomputedby Table BIItabulatestheKcorrectionsto ^bol (o) 4oi(g) + 2.5log Jo do r^x)/o(x) d\ rs(x)4x) d\ ( (B7) O'! V" 1956AJ. X I O.3O 0.15 o. 10 0.05 O.35 O.3O 0.25 0.20 0.15 0.10 0.05 0.00 which iscausedbytheevolutionofbrightest effect (StebbinsandWhitford1948; O.35 O.25 0.20 light signalsemittedbyanebulaat¿1. of /o—t\,whereisthetimereceipt stars comprisingthenebula.Ifthishypothesisis is lessthanthatgivenbytheobservations,and 0.00 following expansionfortherequiredfunction: K (z,ti),whichisthecorrectionderivedfrom at ¿0,whereasweactuallyneedthefunction true, itfollowsthatK?andKvwillbefunctions that achangeofI(A)withtimeisinvolved, This equationhasthesameformthatRobertson the excessisknownasStebbins-Whitford 1956 AprilTHEASTRONOMICALJOURNAL effect canbeincorporatedintothetheoretical assumes forthechangeintotalbolometric present lackofknowledgeI(A)weassumethe the energycurveextantattimeh.Withour tion ofRobertson’squantity¡j,(Robertson1955), magnitude withtime,andhence,byaredefini- the changeinKcausedbyStebbins-Whitford comparison. TheagreementbetweenWalker’s ously madethemavailableforthepurposeof equation connectingWboiand2.Atthepresent 954)* Oneproposedexplanationoftheeffectis tions byessentiallythesamemethodusedhere. time thisseemstobethebestprocedure. His resultswerenotpublished,buthehasgener- mag. Walkeralsocomputed K?andKvforSb lae isfairlygood.Theaverage differenceis0.04 and thepresentvaluesofK? andKvforEnebu- 2 z By theaboveprocedurewehaveevaluatedK In 1948MerleF.WalkercomputedKcorrec- © American Astronomical Society • Provided by theNASA Astrophysics Data System TABLE BII.VALUESOFK(z,to)ANDKv(z,t) F0 K(z, h)=K{z,to)+^(h-to).(B8) (mag.) ACI (mag.) ACI 0.00 i. 16 Kp Kv Kp Kv •47 .21 •93 •71 99 00 25 24 75 50 Pettit’s S(X) Sb Nebulae E Nebulae SW’s S(X) 0.00 I-13 1.23 •57 .76 •25 .11 •94 .41 •36 •55 •23 .00 .76 . 10 •99 .00 •30 . 10 .40 •36 .22 •44 •39 •27 •IS .OO .48 (mag.) ACI (mag.) ACI i. 10 Kp Kv Kp Kv .22 .00 .89 .66 •44 •30 •47 .81 .62 .14 .00 Sc Nebulae E Nebulae SW’sS(X) SW’s S(X) 1.13 .41 . 10 .64 •50 •35 .22 •13 .06 .76 •59 •25 .00 .02 .00 •95 .46 •51 .48 .40 •34 .24 . 12 .00 •34 •30 •25 . 12 .00 •19 counts. H isoneofthemostdifficultproblemsinmodern values ofKdonotexceed0.1mag.Theseresults the [logcz,rn]relationandforstudiesofnebular important forfuture,morepreciseevaluationof show thataproperchoiceofwavelengthwillbe z =oto0.30,andfoundthemtobeA6300 Walker computedtheoptimumeffectivewave wave length.Bychoosingeffectivelengths lated inTableBII. and Scnebulae,thesevaluesarealsotabu- cators ofsuitableprecision,suchasnovae,globu- determining distancestoresolvednebulaethat of possibility.Thedifficulty,course,liesin for anaccuratesolutionisjustontheborderline observational astronomy,sinceeachsteprequired 5500 forScnebulae.Forthesewavelengthsthe for Enebulae,A=6200Sband lengths forminimumKcorrection,overtherange and yetarecloseenoughtoshowdistanceindi- are farenoughawaytohavesignificantredshifts made quitesmallforanappreciablerangeofz. far enoughtothered,Kcorrectioncanbe stars ofhighestluminosity. lar clusters,andthevariablenon-variable the sizeofKcorrectiondependsstronglyon These objectswereidentifiedatthattimeas objects inasampleofnearbyresolvednebulae. Wilson (1923,1939).Evidenceaccumulatedin The zero-pointoftheperiod-luminositylawfor the [logcz,m~\relationforbrightestresolved of thoseobjectswereassumedtobeknownfrom bright supergiantstars.Theabsolutemagnitudes anew eachstepofthisprocedure. the pastfiveyearshasshownneedtoexamine and inM33withrespecttothecepheidvariables. previous calibrationofbluesupergiantsinM31 The correctionfromBlaauwandMorgan’ssolu- tical parallaxcalibrationfirstbyHertzsprung the cepheidswasassumedknownfromstatis- correction increasestheapparent distancemodu- period-luminosity relationforclassicalcepheids. the needforrevisionofzero-point Blaauw andH.R.Morgan(1954)haveshown lus forM31andM33 revisesupwardthe agreement withBaade’soriginal estimate.This tion isATkf=—1.4±0.3mag.,whichingood (1913) andlaterbyShapley(1918)R.E. The determinationoftheexpansionparameter One importantpointmadebyWalkeristhat Hubble’s calibrationof1936wasobtainedfrom H. Mineur(1945),andlaterBaade(1952), APPENDIX C.EVALUATIONOFH 159 O'! V" 1956AJ. X 0 these systems. absolute magnitudesofthebrighteststarsin sions ithasonlyrecentlybeenpossibletotest 160 Ha regionononeplateandaneighboringportion stars. Thetestprocedurehasbeentotaketwo knots inthespiralarmsofnearbyspiralsare Hubble’s assumptionthatthebrightresolved of thecontinuumonother.Comparison plates withappropriatefilterssoastoisolatethe regions fromthestars.Reproductionstwo the twoplatesdistinguishesemissionHn VII forNGC4321,thebrightestspiralin such photographsareshowninPlatesVIand Virgo Cluster.PlateVIshowstheentirenebula taken withthe200-inchonaI03a-Dplatebehind a SchottGG14filter.Thisplateandfiltercom- bination isolatesthespectralregionfromX5100 This regioncontainstheHaemissionline.From filter whichhasabandpassfromX6300toX6700. plate; therightfromaI03a-EplateplusRG2 arm ofNGC4321.Theleftsideisfromthea-D to X6400whichisfreefromstrongemissionlines. H iiregionsinsteadofresolvedstars.Several Plate VIIshowsaplatepairforpartofspiral cation ofthebrightestknotswithH11regions in thespiralarmofNGC4321areseentobe these photographs,thebrightestresolvedknots has beenmadeinallotherresolvednebulae on therightpartofPlateVII.Similaridentifi- prominent H11regionsareindicatedbyarrows they begintoappearabout2magnitudesfainter tested. StarscanberesolvedinNGC4321,but objects appear.Onblue-sensitiveplatestheyare stars. Overtheentirenebulaabout15ofthese than theknots.Thearrowonleftpartof stars. TheseobjectsbegintoresolveinNGC4321 plates. Allindicationspointtoidentificationwith more conspicuousthanontheyelloworred Plate VIIpointstotwoobjectsthatareprobably at m~20.8,whichisconsiderablyfainterthan although itwillbepossibletousethebrightest resolved starsasdistanceindicators,theyare The long-termprogramnowinprogresscalls way eventuallytodetermineHwithprecision. regions. Useofsuchstarsappearstobeonegood faint andmustfirstbeisolatedfromtheH11 Hubble’s (1936b)valueofm=19.0.Hence, first forthisseparationofthestarsfromH11 can beresolvedwiththe200-inchtelescope. regions inallnebulaenorthofb=—15that by thecepheidcriterionbefore apparentmoduli be recalibratedinthenearby systemsofM31, Next, theabsolutemagnitudesofstarswill M33, NGC6822,andtheM81 andM101groups pv vg With theavailabilityoffastred-sensitiveemul- © American Astronomical Society • Provided by theNASA Astrophysics Data System THE ASTRONOMICALJOURNAL 6 6 for theresolvedsystemsarefound.Fromthese same calibratingsystemsthedependenceof The resultingdistancemodulifortheresolved upper luminosityoftheinvolvedstarson systems, correlatedwiththeredshift,ultimately luminosity ofthenebulaewillbeinvestigated. may giveHwithfairprecision.Althoughthis any currentdiscussionofthevalueHmust approach isstraightforward,itobviousthat be consideredprovisional.Twowaysofesti- mating thevalueofH,however,arepossibleat present evidencewillnowbediscussed. this time,and,becauseofitsimportance,the gives H.Thebrightestsystemwithreasonably well knownMistheAndromedanebula,and spiral isindeedoneoftheintrinsicallybrightest one calibrationmethodistoassumethatthis to nebularluminosityexists,which,ifknown, nebulae inFigure10indicatesthatanupperlimit in thesky.Arbitraryasthisassumptionseems, described inthefollowingparagraphs. mined fromtheresolvedstarsinNGC4321,as the resultingvalueofHagreeswiththatdeter- and Swope’s(1954)apparentmodulusm—M is M=—19.92,whichobtainedfromBaade berg’s photometryiscarriedtoanisophoteof nitude M=4.33.Thisabsolutemagnitudeis about 27mag./sq.sec.Allmagnitudesinthis the asymptoticortotalmagnitude,sinceHolm- mag./sq. sec.FigureA3ofAppendixAshows paper, however,refertoanisophoteofabout25 pg that theconversiontermbetweenthesetwocases 0.25 mag.forthephotographichalf-thicknessof be usedwiththepresentdatais,therefore, is about+0.10mag.Theabsolutemagnitudeto first-ranked clusterdataofFigure13givesH= our galaxy.Thesamecriterionappliedtothe absolute photographicmagnitudetogetherwith km/sec per10pcifweadopt—19.82forthe ure 10foralltypesoffieldnebulaegivesH=211 Mpg =—19.82.TheupperenvelopelineofFig- values isduetotheslightlybrighterlimiting vg absolute magnitudeforthefieldnebulae. The absolutemagnitudeforbrighteststarsis parent magnitudeofthebrightestresolvedstars pg obtained bycomparisonwiththoseinM31and in NGC4321.ThesestarsappearatMp~20.8. = 24.25andHolmberg’s(1950)apparentmag- and 15.6,respectively.With respectiveapparent these systemsatphotographic magnitudes16.0 M33. Thebrightestnon-variable starsappearin 180 km/secper10pc.Thedifferenceinthetwo V The well-definedlimitingenvelopeforthefield The absolutephotographicmagnitudeofM31 The othermethodofcalibrationusestheap- 61, No.1237 O'! V" 1956AJ. X © American Astronomical Society •Provided bythe NASAAstrophysics Data System Plate VINGC4321takenwiththe200-inchHaletelescope alOßa-DplatebehindSchottGG14filter. The bandpassofthiscombinationisfromX=5200to-6300. 1956AJ 61 . . . 97H i aVLSmeC0nSplcu0usnreionsare d? Wha3EP,atebehmdSchottRG2filter This >arthe splaarm on theleft°^emarked ontheright.Objectsidentifiedas^tarsaremarked íifcf ¿írvtc- ' combinationisolatesHa.Theexposureontheleft r ;h1-7,1!^(?/r~*ofNGC4321whichisshown inthelowerrightofPlateVITheexposureon t © American Astronomical Society •Provided bythe NASAAstrophysics Data System O'! V" 1956AJ. X 6 2 6 magnitudes are—8.25and—8.50.Furthermore, moduli of24.25and24.15,thestellarabsolute 1956 AprilTHEASTRONOMICALJOURNAL values isM=—8.5,whichwillbeusedhere. Sandage 1953)is—8.7.Themeanofallthese Since thesestarshaveanaveragecolorindex the meanMgatmaximumlightfor5blue, near zero,thecorrespondingMis—8.5.Amore irregular variablesinM31andM33(Hubble accurate valueisnotavailableatpresent.Again using 0.25mag.forthephotographichalf-thick- pg P shall assumethatthetruevalueofHisgivenby pv The solutionofCase2fortheclusters,together by theequationMe=TÍt—5log/. be relatedtothetrueabsolutemagnitudesMt at presentunknown.Theabsolutemagnitudes with themagnitudedifferencesbetweenist, were chosenaccordingtoapparentmagnitude, necessary tocomputeMeforthefieldnebulae. Me computedwithiT=180km/sec10pcwill necessary clusterdata.Sincethefieldnebulae 3rd, 5th,and10thclustermembersprovidethe luminosity function.Sinceaisnotwellknown, field nebulaeandfortheclusterareMo, only thedirectlydeterminedM{m)—5log/is Mo —1.382o-,whereaisthedispersionof Mo, bytheMalmquist(1920)relationM(m)= the correspondingmeanabsolutemagnitude sults. Itisclearthatthevaluesforbrightest M(m) differsfromthemeanperunitvolume, Adams, W.S.,andHumason,M.L.1936,Pub.A.S.P.48, tabulated inTableCIcontainingthetotalre- 180/ km/sec10pc,where/isacorrectionfactor sulting intheMalmquistrelationdoesnotenter and notM(m),sincethestatisticalselectionre- .1945,ibid.44,15. these cases. .1951,Mich.Obs.Pub.X, 7. .1952,Trans.I.A.U.,Vol. VIII,397. .1940,Yearb.CarnegieInstn. 39,20. Baade, W.1931,A.N.243,304. Baade, W.,andMinkowski,R. 1954, Ap.J.119,215. Solution 2ofTableXIVprovidesthedata 107. :2 © American Astronomical Society • Provided by theNASA Astrophysics Data System TabulatedareM(m)whichisrelatedtoMby=—1.382o-. 0 SBo-j-SBa All Types Sc+SBc Class SBb TABLE CI.MEANABSOLUTEPHOTOGRAPHICMAGNITUDESFORNEBULARCLASSESWITH Sa So Eo Sb REFERENCES Field Nebulae*ClusterNebulae 2 — 18.21dr.13 -18.54 =±=-23 -18.37 =L.18 -18.33 ±.24 — 18.04=*=-5 -I8.35 -21 M(m)p —5log/ — 18.OO=b.36 — I7.92dr.26 c 16 H =180•/KMSEC“(lOPC)“ 6 6 9 4321 ism—M=29.05.Themeanredshiftof ness forourgalaxy,thetruemodulusofNGC by 20percent,H=180km/sec10pc,i/H km/sec 10pc.Althoughitisprobablyuncertain the VirgoCluster+1136km/secgivesH=176 from thepresentdata. 5.4 X10yearsappearstobethebestobtainable magnitudes forthevariousnebulargroups.We nebulae maynowbeusedtogivemeanabsolute .1953,Yearb.CarnegieInstn.52,25. Baade, W.,andSwope,H.1954,Yearb.CarnegieInstn. .1950,Ann.Astroph.13,362. Blaauw, A.,andMorgan,H.R.1954,B.A.N.12,95. Bigay, J.1951,Ann.Astroph.14,319. .1950,ibid.,No.128. de Vaucouleurs,G.1948,Ann.Astroph.11,247. Bondi, H.1952,Cosmology,CambridgeUniversityPress. .1930,Ap.J.71,231. .1929,Proc.Nat.Acad.Sei.15,168. Einstein, A.1945,TheMeaningofRelativity,appendixfor Bowen, I.S.1947,Pub.A.P.59,253. .1939,J.FranklinInst.228,131. .1936c,Ap.J.84,270. .1936b,Ap.J.84,158. .1936a,TheRealmoftheNebulae,YaleUniversity Curtis, H.D.1903,LickObs.Bull.2,67. .1953,M.N.113,658. .1941,Sei.Mon.51,391. Holmberg, E.1945,Medd.LundsAstr.Obs.,Ser.II,No. Hertzsprung, E.1913,A.N.196,201. Härm, R.,andSchwarzschild,M.1955,Ap.J.121,445. Hubble, E.1925,Ap.J.62,409. Dennison, E.1954,ThesisUniversityofMichigan,unpub- .1954,Yearb.CarnegieInstn.53,22. .1936,Ap.J.83,10. Hubble, E.,andHumason,M.L.1931,Ap.J.74,43. .1947,Pub.A.S.P.59,180. Hubble, E.,andSandage,A.1953,Ap.J.118,353. .1935,Pub.A.S.P.47,319- Humason, M.L.1931,Ap.J.74,35. .1939,LickObs.Bull.19,33. .1936,Pub.A.S.P.48,14. Humason, M.L.,andWahlquist,H.D.1955,A.J.60, Humason, M.L.,andZwicky,F.1947,Ap.J.105,85. Mayall, N.U.1934,Pub.A.S. P. 46,134. Malmquist, K.G.1920,Medd.LundsAstr.Obs.,Ser.II, The [logcz,m]relationforthefieldandcluster 53, 20. lished. the secondedition,PrincetonUniversityPress. Press, NewHaven. 117. 254- No. 22. Brgst FidNeb Rank 3 Rank 5 Rank 1 Rank 10 Class Mw-S log/ c -19.30 -19.78 -20.25 — 18.98 -18.49 161 1956AJ 61 . . . 97H .1950,Pub.Obs.Univ.Michigan10,19. .1948b,Pub.A.S.P.60,266. .1948a,SkyandTelescope8,3. Mayall, N.U.,andEggen,O.J.1953,Pub.A.S.P.65,24. Mayall, N.U.,andAller,L.H.1942,Ap.J.95,5. 162 Ohlsson, J.1932,Ann.Obs.Lund,No.3. Mayall, N.U.,andWyse,A.B.1941,S.P.53,120. Neyman, J.,andScott,E.L.1952,Ap.J.116,144» Nassau, J.J.,andSeyfert,C.K.1945,Ap.102,377. .1954,Ap.J.120,413. Mineur, H.1945,C.R.Acad.Sei.Paris220,445. McVittie, G.C.1956,GeneralRelativityandCosmology, .1955,Pub.A.S.P.67,82. .1938,Zs.Astroph.15,69. Oke, J.B.,andSchwarzschild,M.1952,Ap.116,317. Pease, F.G.1918,Pub.A.S.P.30,255. .1954b,LiegeSymposiumVolume,LesProcessus Sandage, A.R.1954a,J.59,180. Pettit, E.1940,Ap.J.91,159. Robertson, H.P.1933,Rev.Mod.Phys.5,62. .1954,A.J.59,285. .1951,Pub.A.S.P.63,72. Scares, F.1943,Ap.J.98,302. Sandage, A.R.,andSchwarzschild,M.1952,Ap.J.116, Russell, H.N.1917,Ap.J.45,60. Shane, C.D.,andWirtanen,A.1950,Proc.Amer.Phil. Seyfert, C.K.1943,Ap.J.97,28. Shapley, H.1918,Ap.J.48,89. reference isgiven. Table 1weremadewiththe12-inchrefractorof double starworkiswellknown;itattestedto comparisons withthelatestavailableorbits,ob- tory. Asterisksdenoteremarks,whichmaybe ment ofthematerialintableisself-explana- by themanydoublestardiscoveriesandmeas- parisons arefromothersources,inwhichcasethe recent supplement(Muller1954).Afewcom- tained fromthecatalogofMuller(1953)andits found attheendoftable.Thesearemainly measures of130doublestars,andthearrange- the LickObservatory.Thelistcontains424 ures madewithitbyBurnham,Aitken,Hussey, the 12-inchClark,with valuei4''o59forone tions, elongationsofo'Í25,orless,aredetectable for bright,equalpairs.The micrometerusedis Kuiper, andothers.Undergoodobservingcondi- Chapman andHill,London. nucléaires danslesAstres,p.254. 463. Soc. 94,13. The highqualityofthe12-inchrefractorfor The observationsofdoublestarscontainedin © American Astronomical Society • Provided by theNASA Astrophysics Data System Abstract. Measuresof130doublestars,¿madewiththe12-inchrefractorLickObservatory,arepresented. THE ASTRONOMICALJOURNAL MEASURES OFDOUBLESTARS* By CHARLESE.WORLEY A12 Shapley, H.,andSeyfert,C.1935,Bull.Astr.Obs.Harv., Shapley, H.,andAmes,A.1932,Ann.Harv.Coll.Obs.88, Shapley, H.,andBoyd,C.1940.Proc.Nat.Acad.Sei. .1945,ibid.102,318. .1952,ibid.115,284. .1948,ibid.108,413. Shapley, H.,andMohr,J.1938,Bull.Astr.Obs.Harv., Stebbins, J.,andWhitford,A.E.1937,Ap.J.86,247. Stebbins, J.,Whitford,A.E.,andJohnson,H.L.1950, Strömberg, G.1925,Ap.J.61,353. .Ap.J.89,218. Struve, O.,andLinke,W.1940,Pub.A.S.P.$2,139. Wilson, O.C.1949,Pub.A.S.P.61,132. was placedalternatelyoneithersideofthewire, .1942,Phys.Rev.61,489. •1954.P-J-o,599- .1953,A-J-58,49- Wilson, R.E.1923,A.J.35,35- Whitford, A.E.1936,Ap.J.83,424. for thepositionangles,linejoiningstars scribed byAitken(1935)wasused.However, obtained. Forthedistances,darkenedwireswere and themicrometerrotateduntilparallelismwas lower powers. generally 600,withafewmeasuresmade Zwicky, F.1938,Pub.A.S.P.50,218. made. angle, andfourdouble-distancesettingswere used whenpracticable.Ordinarily,fourposition- 2''o, showingorbitalmotion.Certainwidepairs principally ofpairshavingdistanceslessthan telescope, havebeendescribedfullyelsewhere revolution ofthemicrometerscrew.It,and have beenmeasuredasa partofacontinuing (Holden 1887).Themagnificationusedwas 43. 26, 41. No. 899,16. No. 907,p.6. Ap. J.112,469. * LickObservatoryBulletin,No. 541. A methodofmeasurementsimilartothatde- The programofobservationhasbeenmadeup and LickObservatory,MountHamilton, Mount Wilson-PalomarObservatories, Carnegie InstitutionofWashington, California InstituteofTechnology, University ofCalifornia, 61, No.1237 1955 July.