194lApJ 94. . .55C 55 scattering, are:Messier46,0.00mag.and1450parsecs;50,0.301210 galactic clustersemphasizetheneedforthoroughinvestigationofinregionswhereobscura- presence ofveryblueAostarsandalsotheplanetarynebula,NGC2438,whichislocatedwithinap- Messier 46,50,andNGC2324—confirmthesmallnessofselectiveprobablyalso Way fieldnearMonocerosandCanisMajorarebeingobserved.Theresultsforthreeoftheclusters— tion isabsentorsmall.ForthisreasonanumberoftheclustersinrichandrelativelyuniformMilky parent boundariesofthecluster,combinetomakeMessier46anunusualobject.Thedistancesob- in slopeandthatthegiantbranchisabruptextendsfromabsolutemagnitude+1to—2.InMessier given inthetext. the generalabsorptioninthisdirectiontoadistanceofapproximately3300parsecs.Thecolorexcesses 46 theslopeofmainsequenceappearstobesignificantlylesssteepthaninotherclusters.The NGC 2324,0.30mag.and3320parsecs.Spacedensities,frequenciesofcolorindices,otherdataare tion ofitsphysicalmembershipintheclusterunsettled;radialvelocityMessier46b4i-4km/sec evident theimportanceofclearregions,forfromunobscuredMilkyWayfields is locatedonly35°fromtheanticenterdirection,coupledwithabsenceofextragalacticnebulae tained fortheplanetarynebulabyvariousworkershave,becauseoftheirwidedispersion,leftques- and limitationsusuallyintroducedbyabsorptionaretherebylargelyavoided.Thegalac- system issuggestedasapossibleexplanation. contains negativecolorindicesinspiteofitslowlatitudeandgreatdistance;thecolorsshowanormal the planetaryisnotamemberofcluster.NGC2324,distantcluster,remarkableobject,forit (XX 4300-6200)anddistances,correctedforthesmallgeneralabsorptionbymeansofi/Xlaw tion ofobjectsinourstellarsystem.RecentinvestigationsbyShapley,Bok,andothers must comethemostdefiniteandfar-reachingofourknowledgeconcerningdistribu- these fields,suggeststhatconsiderableabsorptionmustoccuratdistancesgreaterthan3300parsecs. main sequenceandanindicationofagiantbranch. have alreadyshownthevalueofresearchinunobscuredfields.Theuncertainties tic clusters,also,aremostprofitablyobservedintheclearregions,anditseemslikely taining obscuringcloudsandextendingtoadistancemuchgreaterthanthe“average”radiusof Either anincreaseddensityofabsorbingmaterialattheboundariesgalaxyoraspiralarmcon- (obtained byStruve)—differswidelyfromthatoftheplanetary(+77km/sec)andshowsdefinitely from theobservedrelationsbetweencolorindices andtheapparentmagnitudesof inferred fromthelowcolorexcessesofsomeclusters;and,becausefinely that insomecasestheymayfurnishpowerfultoolsforinvestigatingunobscuredfields color excessesareanindicationatleast,ifnotactualmeasure,ofthegeneralabsorption. divided natureoftheinterstellarmaterialresponsibleformostobscuration, to distancesasgreat4000parsecs.Theabsenceofappreciableabsorptionmaybe self-determinate, andtheassumptionofauniform absorbing layerisnolongernecessary. cluster starsis,inthelightofpresentknowledge thenatureofinterstellarabsorption, Formally thethreeessentialunknownsmaybeobtained fromtheequations THE GALACTICCLUSTERSMESSIER46,50,ANDNGC2324 . Theproblemofdeterminingthecolorexcessesand distancesofthegalacticclusters © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The uncertaintiesintroducedbyinterstellarabsorptionintodeterminationsofthedistances The color-magnituderelationsshow,inMessier50,thatthemainsequenceiswelldefinedandnormal The irregularstructureoftheobscurationinMilkyWayhasmadeincreasingly The absenceofappreciableabsorptiontolargedistances,particularlyinthecaseNGC2324,which m +A=f(CE), (1) INTRODUCTORY REMARKS 0 JAMES CUEFEY A =KE,(3) ABSTRACT (2) 56 JAMES CUFFEY where, of course,

m0-M=s (log r - i) = f{C + E) - f(C) - A .

The unknowns are r, the distance of the cluster; T, the absorption; and E, the color excess. Equation (i) represents the relation between color and ; m0 is the “unobscured” apparent magnitude of a given cluster . Equation (2) is the relation between color and for in the solar neighborhood or in some standard unobscured cluster of similar type whose distance is known from other data, spectral types, for example. Equation (3), which completes the problem, is fur- nished by the law of scattering; E is a constant, depending upon the wave lengths in which the photometric measurements were made. If the scattering varies as i/X and the colors are based upon magnitude differences between X 4300 and X 6200, then ^4 = 2E for red light (X 6200). Such a relation, although satisfactory when the absorp- tion is small, may become unreliable if the absorption is large, for then deviations from the assumed i/X law and irregularities in the value of K from one obscuration to another might become important. That the form of the M-C relation is precisely the same for all clusters may, of course, be questioned. The color-magnitude diagrams do, indeed, show striking differ- ences, especially for the brightest stars in the clusters. The main sequences in most of the clusters, however, appear to be very similar in form, and therefore it seems reason- able to conclude that the M-C relation may be assumed constant for main-sequence stars, but not for the giants. The spectrum-magnitude diagrams, which are essentially similar to the color-magni- tude relations, have been shown by Trumpler1 to differ, although again mostly in the forms of the giant branches. The main-sequence stars in the spectral data seem to be characterized by a well-defined and, in most cases, constant relation between spectral type and absolute magnitude. Thus the conclusion that distances derived from the giant branches in the color-magnitude diagrams are entitled to low weight is confirmed by the spectral-type data. One additional conclusion to be drawn from the spectral ma- terial is that the brightest main-sequence stars in the majority of the galactic clusters are B and A stars. In only one cluster in the hundred classified by Trumpler are they of later type, and here they are F stars. The rarity of the f type of cluster is a fortunate circumstance, for, if spectral types were not available, such clusters might possibly give erroneously high color excesses on the basis of color-index data alone. B. Strömgren’s work2 shows that the form of the Russell-Hertzsprung diagram may, as suggested by Kuiper,3 depend upon the hydrogen content of the cluster as a whole. Trumpler’s and Rieke’s data, examined by Kuiper,3 indicated that for the main se- quences observed in several clusters the form was closely the same and that the large differences occurred mainly in the giant branches. Our present empirical knowledge, therefore, appears to show reasonable constancy in the M-C relation for the main sequences in the galactic clusters. In the future, when abundant observational material becomes available, it may be possible to allow for the effects of variability in the M-C relations by adopting several, each one appropriate to clusters of one given type.

DESCRIPTION OE REGION Messier 46 (NGC 2437), Messier 50 (NGC 2323), and NGC 2324 are situated in the rich and relatively uniform Monoceros-Canis Major region of the Milky Way. Close inspection of small-scale photographs4 reveals, however, that obscuration is not entirely 1 Lick Obs. Bull., 14, 154, 1930. 3 Ap. J., 86, 186, 1937. 2 Zs.f. Ap., 7, 222, 1933. 4 See Ross-Calvert Milky Way Atlas, Pis. 36 and 37.

© American Astronomical Society • Provided by the NASA Astrophysics Data System PLATE III

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© American Astronomical Society • Provided by the NASA Astrophysics Data System 194lApJ 94. . .55C © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem PLATE V NGC 2324 # 194lApJ 94. . .55C 6 s absent fromthefield.Messier50appearstobeatedgeofasmallobscuringcloud, and Messier46isnearto,butprobablynotobscuredby,averythinabsorbinglaneex- and fromangulardiameters,areshownbythepresentsurveyofredcolorindicesfor uncertainties inthedistancestabulated,whichwerederivedfrombrighteststars tending fromasmallandpoorlydefinedcloudtothesouthwest.NGC2324,alone, seems tobeinafieldquitefreefromobscuration. 1119 starsintheseclusters. Messier 46.. NGC 2324.. Messier 50.. Observatory. RedmagnitudesweremeasuredonEastmanSpectroscopicplates,type made attheprimefocusof36-inch,F/5aluminizedreflectorGoetheLink on CramerHi-SpeedSpecialplates.Effectivewavelengthsofthemagnitudesystems polar-sequence stars.Themagnitudesadoptedandusedinthepresentphotometric are approximately6200and4300A.Theredmagnitudesusedthosegivenby ing inthispublicationtheredmagnitudeswerederivedfromphotovisualcolorin- possible circleofconfusion.Bothpolarandcluster plates,therefore,havealmostequally dices bymeansofaplottheavailableredindicesagainstyellowcolorfor good images. mirror whentheexposuresweremade.Nearlycircular imagesofgoodquality,however, work aregiveninTable2. C. Payne-GaposchkinandS.Gaposchkin;forthefainterpolar-sequencestarsnotappear- 103-E, takenthroughaCinéRedfilter(EastmanNo.28),andphotographicmagnitudes able errorsisgiveninTable3. were obtainedbyusinga9-mm.eyepieceinfocusing, inordertoobtainthesmallest result, manyofthemmay beconsideredeitheraspolarcomparisonsor as exposures tained fromthepolarcomparisons.Asummaryof theplatematerialandofprob- 6 The co-ordinatesandotherdatapreviouslypublishedareshowninTable1. © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Magnitudes andredcolorindiceswerederivedfrompolarcomparisonexposures Astigmatism, whichhasrecentlybeenentirelyeliminated, waspresentintheprimary The clusterstarsweremeasuredwithimagescales calibratedonthesequencesob- The photographsoftheclusters weretakeninserieswiththoseofthepole, and,asa S HarvardAnn.)89,No.5,1935. Scares,Trans.I.A.U.,1,71,1922. Lick Obs.Bull.,14,154,IQSO- h 11 \2oo° +5-3/ \ 181t+4-8/ \ i89?5+0.1/ f737“2 —•i4°6\ fó^S^ -8?2\ fó^g^o +i°.2\ 1900 DISCUSSION OFPOSSIBLESYSTEMATICERRORS GALACTIC CLUSTERS57 Diam. PHOTOMETRIC DETAILS i6' 27 f HDstars. 8' 5 Type Il2r 12m 12m ra ib-a TABLE 1 11B9-A1 7B8—Aof Spectra Î StarClusters,Appen.B,1930. 710 780 Sp. Trumpler* Diam. 1720 860 610 Distances 4370 -6920 1150 -1820 5oo:-8oo: Shapleyî 194lApJ 94. . .55C 7 for systematicerrors,remeasurementofthesequencemagnitudesinMessier46and magnitude systemsandseewhattheireffectsuponthecolor-magnitudediagramsmight expect toobtainanestimateofupperlimitthesystematicerrorspresentin sidered fundamental,and,sincetheyarebaseduponthegreatestnumberofplates, comparing oneclusterwithanother.Thereductionsaspolarcomparisonswerecon- in extremecasesbe.Bothimage-scalemeasurementsandalsomadewith NGC 2324withrespecttothoseinMessier50wascarriedout.Inthiswaywemay they wereusedforobtainingthecataloguedmagnitudes.Inordertotestsequences polar comparisons,thefollowingremarksconcerning thequalityofmagnitudesmay the newRossphotoelectricphotometerofKirkwoodObservatorywereused.The the resultingsystematicdifferencesbetweenmagnitudesinMessier50andthose from m=11.5to15.0.Brighterthanmagnitude 11.5,theremaybelargesys- Messier 46andNGC2324areshowninFigure1. Althoughtheplatematerialsuitable magnitudes inMessier50,merelyasaworkingbasis,wereassumedtobecorrect,and brightest sequencestarsdonotseriouslyaffectthe conclusions. ever, arefainterthanmagnitude11.5,sothatuncertainties inthemagnitudesof be appropriate. tematic differences,andthecolorsmaybeuncertain. Mostoftheclusterstars,how- 32 31 30 58 twelfth magnitude,thesystematic differencemaybegreaterthan0.2mag.; butagain NGC 2324areingoodagreementfromm=13.0 towg=17.5.Brighterthanthe for intercomparingtheclustersislittlemorethan halfasextensivethatusedforthe the SocietyofSigmaXI. 28, 27, 26, 25 ■ 24 23 22. 21. 20. 14 12. 11. 10. 29 19 I? 16 15 IS 18 r vg P © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem * Derivedfromtheredindices,whichwereobtainedphotovisualdata. 2a. Photographicmagnitudes.—Thephotographic sequencesinMessier50and i. Redmagnitudes.—Theredsequencesinallthree clustersareingoodagreement 7 Acquiredwiththeassistance ofgrantsfromtheAmericanAcademyArtsandSciences, andfrom No. 15-31 14.89 14.61 14.10 13.92 13.46 13-34 12.98 12.28 10.52 10.08 16.40 16.19 15-87 13-59 12.68 11.58 11.27 10.92 16.75 11.88 9-77 9.ii ■pg 1I 0.75 0.48 0.31 0.31 0.99 0.99 0.78 0- 5 5 0.64 0.33 0. 8 3 0.96 0.73 0.97 0.67 i .02 i .02 •5 i .00 1- 3 7 1. 16 1.14 i. 72 Polar SequenceStars JAMES CUFFEY IO. 19 IO.25 12.35 12.20 IO.91 IO.63 12.57 11-53 II.03 13.89* 13.24* 13.27 12.96 12.47 11-95 1503* 15-05* 14.85* 14.16* 15-24* 9.60 8.80 9.46 pr TABLE 2 35- 33- 38. 37- 36. 34. 39 r s r ios. nr. lor. 121. I2S. ns. I3S. I4S, 8s, 8r. 9- 9- 6s. 7- No. 18.20 17.24 17.06 18.01 18.58 17.78 17-63 II.44 IO.96 13.22 11-95 11.36 13- 7 8 12.61 15- 3 0 15.28 14- 7 3 14.49 15.51 15-35 16.02 pg 0.72 0. 9 6 i. 70 i. 62 2.00 1.50 i .06 1-43 1.77 i .80 1.44 1.30 1.67 i .42 I-I5 1.50 1. 10 1.79 1-45 i 05 1-45 15-44* 16.50* 16.24* 16.28* 16.57* 15.81* IO.4O II.89 IO.5I 16.58* 13-88* 13-39* II.99 II.42 IO. I4 14-57* 14.30* 14- 13* 13- 23* 14.06* 9.29 194lApJ 94. . .55C polar comparisons,causedbyskyerror,areresponsibleforthelargerprobable errorsinthecaseofsequencemagnitudes, region andpolemakesprecise photometrydifficult;andfurtherinvestigation ofthe scale error.Thesensitivity ofthelong-focusreflectortodifferencesinseeing between it ispossiblethatthephotographic magnitudesinMessier46maybe affected with tude. Inviewoftheagreementbetweenmagnitudes inMessier50andNGC2324, siderable scaledifferencemayexistandreach 0.30mag.atthefourteenthmagni- seeing andalso,althoughprobablytolessextent,byirregularitiesintransparency. Thesystematicdifferencesbetweenindividual NGC 2324.. Messier 50.. Messier 46.. NGC 2324. Messier 50. Messier 46. this isnotserious,foralmostalltheclusterstarsinNGC2324andmajorityofthose Messier 46and50appearstobegoodbetween11.5mag.12.5Con- in Messier50arefainterthanwg=12.0. P © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem * Includesplateerror,measuringandskyofwhichtheerror isthelargest,andcausedbyirregularitiesin t Includesplateandmeasuringerrorsonly. 2b. Photographicmagnitudes.—Agreementbetweenthephotographicsequencesin m / 9o-io5 \io.5-15.0 .13-2-15.3 12.5- 1 5.0 8.5- 12.5 Interval 9-5-13 2 No. No. orSeriesExposuresofCluster Red Red 30 30 30 min. 15 15 3 7 Sequence Magnitudes Exp. io^ogó ±0.034 p.e. •°S3 .068 .054 .088 Observational Material GALACTIC CLUSTERS No. 1 14.0- 17.5 10.0- 17.5 ii.5-14.0 130-17.5 Probable Errors 9“o-i3fo 9.0-11.5 Interval TABLE 3 Blue 30 30 min. 30 iS iS iS Blue 8 8 Exp. ni ±0.083 ±oio4 p.e. . 100 .058 .119 .062 Cluster Exposures Mean Altitudeof UJI Red io-i3 Interval 13 -16 ii -13 10 -13 13 "iS 13 “iS 43 34-5 38.4 Red Internal AccuRAcvt Blue ±0.030 ±0^059 43 p.e. 39-4 28.8 .049 .038 .030 .030 tinction Corrections Mean NumericalEx- m1] io-i4 Interval 0^03 is -17 0.01 ii -IS 10 -14 14 -18 14 -17 Red .01 Blue b1 ±o!o63 ±0.038 Blue 0.08 0^13 p.e. .02 •055 ■055 .042 .038 59 194lApJ 94. . .55C photographic magnitudesinMessier46witharefractor,orlargeSchmidtcamera, pens thatevenif,asoneextreme,theentiredifierencessuggestedbyFigure1areas- m =14.0.Thecorrectionstendtoshiftthediagramsinaverticaldirectionand might proveprofitable.PhotometricerrorsofthetypeshownbyFigure1,however, 6o JAMESCUFFEY shown inFigures2,aandb,2»4,b.Thelargedotsrepresentstars introduce uncertaintiesintothedistancesonly. excesses andtheshapesofcolor-magnituderelationsforstarsbrighterthan paper, asderivedfrompolarcom- and thoseinM46NGC2324. between magnitudesystemsinM50 tions tothecolor-magnitudediagramswhichresulthavesmalleffectuponcolor sumed tobesystematicerrorsinthemagnitudesanyoneclusteralone,correc- do notappeartomodifyseriouslytheconclusionsdrawninpresentpaper.Ithap- logue); ordinates,valuesobtained parisons only(abbreviatedcata- from comparisonwithM50(abbr. Abscissae, magnitudesgiveninthis ground, theresultsareoflowaccuracy,and densitiesattheverycentersof cat.) minuscataloguedvalues. The spacedensities(Fig.6,b)werederivedfrom aPlummeranalysisofthestar large togiveagooddeterminationofthespace densitiesforseparatecolorgroups. counts usedinobtainingFigure6,a.Because of theirregularnatureback- centers oftheclustersisevident,althoughnumbers involvedarenotsufficiently clusters areuncertain. r the cluster’sbrighterstars. Theslopeofthemainsequenceappearstobe significantly color excess(Fig.7),show boththeabsenceofabsorptionandunusual bluenessof 8 8 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Color-magnitude relationsforthecentralandouterzonesofclustersare Fig. i.—Systematicdifferences The extraordinarilyblueAostarsinMessier46, whichsuggest—0.20mag.asthe Spectrafromunpublishedwork byDr.Trumpler. RESULTS ANDCONCLUSIONS fairly complete,whileforMessier46itisprobablethat members. ForMessier50andNGC2324thedataare by smalldots;theyare,therefore,moreprobablycluster greater scatteringduetotheproportionof closer tothecentersofclustersthanthoseindicated volved inthecasesofMessier46and50.Ex- field starstoclusterstars.Becauseofthelimited ly bythecentralregions,inwhichmostofstarsare main sequencesareshownbyallthreeclusters,especial- the photometricfieldofreflectorhasbeentoosmall outer zonesshowsimilarmainsequenceswith,however, to includetheouterpartsofcluster.Well-defined indicates thatinFigures2,a,and3,morethan70per amination oftheouterzonestheseclusters,however, cluster members(seeFigs.2,0,3,a,and4,a).The tive statisticaldataonthenumbersoffieldstarsin- the reflectorplatesitwasimpossibletoobtainquantita- The greaterconcentrationofthewhitestarsto the cent ofthestarsbrighterthanm=13.0aremembers measure colorsintwofieldsremovedfromtheclusterby stars. OntheplatesofNGC2324itwaspossibleto of theclusters,andmorethan50percentfainter exterior regionsshowthat80percentofthestarsin Figure 4,a,belongtothecluster. included byRing3ofthecluster.Thedataonthese i o'andhavingacombinedareaofskyequaltothat r Frequencies ofcolorindicesareshowninFigure 5. messier 46 194lApJ 94. . .55C 9 less steepthaninthecasesofMessier¿o,NGC2324,andmostclustersobserved thus far.Thepossibleeffectsofscaleerrorsinthemagnitudesystems,firstcause planation. If weassume,e.g.,thatthesystematic differencesbetweenthemagnitudesinMessier 46 andMessier apply thecorrectionsindicated byFig.1tothecolor-magnituderelation,anddistance ofMessier46 to besuspectedfortheabnormalslope,wereexamined andfoundaninadequateex- becomes 1850parsecs.Ifweassume, asperhapsabetterapproximation,thatthemeanof thesequences changing thecolorexcessorshapeofcolor-magnitude diagramforstarsbrighterthanm=14. 50 might,asoneextreme,bedue entirelytosystematicerrorsinthemagnitudesMessier 46,wemay r © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 9 ErrorsofthetypesuggestedbyFig.1tendtoshift relation asawhole,withoutappreciably Fig. 2.—Color-magnitudediagramsofM46.a,rings1,2,3;b,4,5 Fig. 3.—Color-magnitudediagramsofM50.a,rings1,2, 3;ô,rings4,5 RED INDEX GALACTIC CLUSTERS6i RED INDEX Ó2 JAMES CUFFEY

In form the color-magnitude relation in Messier 46 resembles the relations obtained by Strömgren10 for the Russell-Hertzsprung diagrams for groups of stars all having low hydrogen content. Strömgren’s material predicts for such groups, however, that no stars earlier than A5 or Fo should be present, while in Messier 46 the colors indicate the presence of B stars.

RED INDEX RED INDEX

a b Fig. 4.—Color-magnitude diagrams of NGC 2324. a, rings 1, 2, 3; b, rings 4, 5

Fig. 5.—Frequencies of color index, M 46, M 50, and NGC 2324

The group of five subgiants near mr = 11.7 and Cr = 1.2 have absolute magnitudes + 1, approximately. Since they are distributed almost at random in the central region of the cluster, with normal main-sequence stars near them, their low luminosities com- pared with the luminosities of the stars which apparently form the cluster’s giant branch in Messier 46 and Messier 50 is correct, we find, upon applying half the indicated correction to the color- magnitude diagrams in both clusters, that they are so shifted that the distances become: Messier 46, 1600 pc., and Messier 50, 1000 pc.; as before, the color excesses are unaffected. Because of the uncertain- ties involved in evaluating the systematic errors from the limited material available for intercomparing the clusters, however, it seems best to adopt as correct the distances given in the text, which are based upon the best material, the polar comparisons, alone. 10Zs.f. Ap., 7, 222, 1933.

© American Astronomical Society • Provided by the NASA Astrophysics Data System o LO

CT) GALACTIC CLUSTERS 63

are probably not due to obscuring material in the cluster but rather to intrinsic peculiari- ties. CT) The modulus and distance for Messier 46, if we use the M-C relations previously derived in and NGC 2281 as standards, are 10.8 mag. and 1450 . The planetary , NGC 2438, which is situated only 7' from the center of Messier 46 has a of +77 km/sec, or +60 km/sec if corrected for solar

Fig. 6.—a, abscissae, distances from center of cluster; ordinates, areal densities, expressed in stars per 1.18 sq. min. for M 46 and M 50 and in stars per 0.49 sq. min. for NGC 2324. Limiting wpg: M 46, 18.0; M 50, 18.4; NGC 2324, 18.3. 6, space densities (stars per cubic ) as a function of distance from center of cluster. Limiting Mpg: M 46, +7.2; M 50, -f-7.2; NGC 2324, +5.1.

Fig. 7.—Relation between color and spectral type for M 46. (From unpublished data by Dr. R. J. Trumpler.)

motion;11 distances given for it by various workers are: 830 parsecs (Camm), 1660 par- secs (Vorontsov-Velyaminov), and 3920parsecs (Berman). The mean, 2100+900 par- secs, may have little significance since the individual values were not entirely inde- pendent. Thus the existing data on distances leave unsettled the question of the rela- tionship between the and the cluster. In order to solve the problem, Dr. Struve has very kindly obtained radial velocities for several stars in Messier 46 with the McDonald 82-inch reflector. Judged from their positions in the color-magni- tude diagram, these stars should all be members of the cluster. The velocities, which depend, in general, upon Hb, Hy, Hß, Mg 114481, and Ca II 3933, are shown in Table 4. 11 Campbell and Moore, Pîib. Lick Obs., 13, 169, 1918,

© American Astronomical Society • Provided by the NASA Astrophysics Data System 194lApJ 94. . .55C 12 13 o 7 o 7 from thecentralregionofclusterareshownby Figure4,a.Thecolorexcessappears true distance,basedmostlyuponthemainsequence,aren.omag.,0.30mag.,and lines mayhaveblendedwiththestellarlines;but,inasmuchasmeasuresshowno surrounding sky. giant branchwithrespecttothecolor-indexaxismaynotbereal,inasmuchas nebula, +77km/sec,makesitsphysicalmembershipintheclusterveryunlikely. is probablyrealandduetothegalactic-rotationeffect,whichwouldgivearatio between themeanstellarvelocity,+41.4km/sec,andCa11+30.2, fore theplanetarynebulahastraveledmorethanamere10 parsecsofthefewhundredthatmaynow it isnotpossibletodeterminesatisfactorilytheiractualrelative positionsinspaceatthattime.Thus,if to beonly0.30mag.,althoughthetruedistanceis 3320parsecs. near theclusterratherthantoanextendedcloudcoveringappreciableareaof accounted forbythesetwocauses.Itisevidentthatthevelocityofplanetary and thesolar-motioncomponentis+17.Henceobservedmotionofcluster of 2betweenstellarandinterstellarvelocities.Atthedistancecluster(X=200, lines, theywereincludedinformingthemeanvelocityforeachstar.Thedifference conspicuous differencebetweentheCa11velocitiesandthosedeterminedfromother the propermotion(Anderson,LickObs.Btdl.,17,30,1934) oftheplanetaryis,asseemslikely,referred colors forstarsbrighterthanm=10.5areuncertain.Themodulus,colorexcess,and giant branchextendsfromabsolutemagnitude+1to—2.Theslightinclinationofthe sequence starsandsomeshowappreciablerotationalbroadening.TheinterstellarCa11 64 JAMESCUFFEY termination ofthedistance theplanetarymightshowthemtobedecidedlyinerror. he betweenitandthecluster. Theseconclusions,however,areextremelyuncertain,and abetterde- tion backwardintime,itseemsprobablethattheplanetary phenomenonwillhavedisappearedlongbe- been amemberoftheclustermaybederivedfrom“quasi-ages” oftheplanetarynebulae,obtained The propermotion,however,islittlemorethantwiceitsprobable error,andtheseparationistherefore to clusterstars,then,1.7X10yearsago,thetwoobjects wereseparatedintheskyby30ormore. 1.7X10yearsago,thedistancesofplanetaryand theclusterfromsunwerecomparable, Dr. Struvewritesthatthespectrallinesareverypoorinquality,sinceallmain- ß =+5?3)thegalactic-rotationcomponentinlineofsightisabout+25km/sec Concerning theobservationalmaterialfromwhichradialvelocitieswereobtained, extremely uncertain.Anargumentwhichmayshowdefinitely thattheplanetary,assuch,canneverhave by Whipple{HarvardBull.,No.908,1938),ofwhichtheoldest isonlyiosyears.Thus,intheextrapola- 1210 parsecs.Thecolorexcessisprobablyduetothesmall,localizedobscurationseen r 13 12 In Messier50themainsequenceisnormalinslope,andanabrupt,almostvertical © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem A normalmainsequenceandanindicationofagiantbranchwhicharisesmainly SeeRoss-CalvertMilkyWay Atlas,PI.37. Althoughitispossibletoconcludefromthediiïerence between theradialvelocitiesthatatan 469. 93. 59- 78. 3- Means. Cat. No. MESSIER 50 Velocity +38.3 +41-4 +44-0 km/sec TABLE 4 nog 2324 Mean 49.6 391 35-8 Velocity +47 km/sec +30.2 +37 Ca ii 49 15 3 Spectrum Ao Ao Ao B Ao 9 GALACTIC CLUSTERS 65

The surprising result that so distant a cluster should show so small a color excess is perhaps somewhat more plausible when we realize that it is only 350 from the anticenter direction in our galactic system. It is also surprising, however, that, in spite of the low absorption indicated by NGC 2324 to a distance within 2 kiloparsecs of the usually accepted boundaries of our , almost no extragalactic nebulae have been observed in this field. Near NGC 2324, Hubble14 finds only two nebulae, and near Messier 46 and Messier 50, none. The total photographic absorption between the and outer space, therefore, is probably at least greater than 2.5 mag., of which less than 1 mag. takes place closer than 3300 parsecs. The additional absorption, amounting to a magnitude and a half or more, must arise from the last 2 kiloparsecs near the edge of the system. An obscuring cloud directly beyond NGC 2324 would explain the observations, but other and less artificial explanations immediately suggest themselves. One possibility is that we have here evidence for a zone of absorbing material encircling the outer boundaries of our system, similar to those observed in NGC 4565, NGC 4594, and other extragalactic systems.15 Another, and possibly preferable, interpretation is that our system, with both stars and obscuring clouds, extends along a spiral arm in this direction to a distance considerably greater than its average radius. The above conclusions, however, are tentative and are subject to large uncertainties. The ratio between color excess and general absorption cannot be regarded as accurately known, and the difficulties involved in estimating the absorption from the nebulae are by no means negligible. It is hoped, however, that additional observational material will provide more reliable information and that the remaining galactic clusters near Canis Major, which are now being observed with the reflector, will provide data for a better understanding of this interesting region.

It is a pleasure to thank Dr. Goethe Link for the use of the 36-inch reflector of his observatory and Indiana University for the post-doctoral fellowship by means of which the above research was carried out. The kindness of Dr. Otto Struve and of Dr. R. J. Trumpler in supplying observational material not otherwise accessible to the author is gratefully acknowledged. Kirkwood and Goethe Link Observatories March 8, 1941

Ap. 79, 41, 1934. 15 See H. D. Curtis, Pub. Lick Obs., 13, 45,1918.

© American Astronomical Society Provided by the NASA Astrophysics Data System 194lApJ 94. . .55C 66 JAMESGUFFEY No. 34 33 32 31 30 60 49 48 47 46 45 40a 40 36 35 37 52 50 44 43 42 41 39 38 68 67 66 65 64 63 62 61 59 56 55 54 53 51 29 28a 28 27 22 20 26 25a 25 24 23 19 18 17 16 15 12 10 58 57 21 H 13 11 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem * Symbols:s=sequencestar;d=double; c=closetobrightstar;t=offchart;b=blend;|=starsclosetogether. ga 9 6a 4 3 8 6 7 5 1a 2 CATALOGUE OFSTARSINMESSIER46,50,ANDNGC2324* 10-45 14- 5 1 12-43 14.06 12.30 15.92 1512 12.32 16.05 14.24 12.88 12.06 16.71 15- 68 14- 59 15-23 12.97 11.62 17.42 12.44 1705 11.04 1509 12.65 16.20 16.22 14.86 12- 43 11.01 14.90 12.42 16.97 16.24 1511 16.02 12.17 14.66 12.68 15- 3 4 16. ii 14.44 15.78 1489 14-35 14.69 14-54 12.38 14.70 12.38 1518 16.62 16.19 16.24 14- 93 13- 75 15- 74 13- 78 12.14 14.87 13- 36 10.67 14- 54 15 •61 13- 08 12.50 11.69 16.76 12.49 11.04 10.35 10.16: 15-99 9.20: 9.40: 'pg 12.24 14.84 10.74 13-66 12.46 13- 60 14.01 13- 37 12.30 15-28 14.47 13-58 14.22 12.92 10.42 12.53 13-27 ii .28 14.78 14.01 12.70 11.66 11.07 14.46 12.67 15.04: 14.89 14-39 14- 5 2 13- 8 8 12.13 14.00 12.66 13-93 13-87 14.48 14.07 13-71 13-55 12.25 14.54 1369 14- 58 13-80 13-94 12.57 14.04 15.09 11.82 14- 35 14.56 13.59 i5-3o: 10.91 12.35 14.21 12.64 14.98 13-97 14.03 1315 12.68 12.03 1515: 12.63 11.32 10.53 12.52 14-75 10.18 14.70 9.10: 9.40: -0.14 -0.14 -0.19 -o. 24 -o. 29A0 -0.09s -o.2IS -0.27s -0.65s -0.40s -0.25s -0.07s -o.18s -0.34s -0.14s -0.28s -o.i8sAi -0.02SAo O.40 0.02 0.80 0.72 0.81 0.04 0.66 0.82 0.80 o. 19 0.57s 0.05 0.92 0.38 0. 05s 0. 19s O.I3S 0.72s 0. 85s 0.87s 0.00SB7 0.57 0.64 0.76 0.66s 0. iosAo 1-35 1-50 0.74 i. 20s 1.41 1.27 1.30 1.38 1-43 1.06 1.44 1.89 I-43S 1.2IS I .Oís 1. oís i •75:s I.82S 1.373 I .42S 1. 24s 1.15s i.93:s 1. 6i:s 1.47 1.14 1-53 1. 18s 1.29s . 79 No. 141 140 139 138 108 137 136 ISS 134 133 132 ISO 129 128 109 107 106 100 126 120 114 US 112 HO 105 103 102 101 131 127 125 124 123 122 I 21 119 115 117 116 US 111 104 80 99 90 87 85 98 97 96 95 94 93 92 91 89 88 86 84 83 82 81 69 78 77 76 75 74 73 70 78a 72 71 16.29 13.29 15-77 15-58 14.71 13-85 15.42 15.69 13-66 10.76 14.02 16.05 ii .22 13 01 15-94 11.62 1436 I2.3I 13 06 16.05 10.66 16.00 11.40 16.42 11.72 12.46 15-80 10.56 1513 1505 15-65 15.69 16.36 15.89 15-80 16.58 10.46 12.46 15.98 ii .19 14.27 15-75 14.50 11.05 1501 11.02 14.65 11-54 1316 16.00 15-55 16.25 16.32: 10.55 I5-38 14.72 15-21 12.62 13-15 13.64 11-35 15-19 13.48 13-45 14.79 13-65 16.24 ii .19 13-41 15-59 1508 15.69 12.68 15.49 Messier 46 ‘'Pg 13.04 13- 47 10.92 14.63 11.63 14-93 14.64 12.01 12.52 12.48 11.94 13-37 14.68 14.68 12.45 10.85 14.70 11.58 14.76 12.00 13- 86 14.08 10.85 14.50 14.28 1413 14.50 I3-8o 13.48 14.70 IS 03 14.62 14.38 14.60 14- 45 14-30 10.64 13.42 14- 50 11.74 13.70 14.68 12.48 11.42 13.09 I3-78 14.92 11.56 11.47 13-20 14.26 14.08 13.85 11.82 12.86 14.74 14-54 14-39 14.91 14.76 14.38 12.55 14-25 12.81 14- 7 5 13- 1 9 13-33 11.58 13-34 13-37 14.61 12.66 10.72 14.17 m. -o. 16A1 -0.18A0 -0.41 -0.03 -0.39 -o.i7d -0.08 -0.19 -0.18 -0.28 -0.55 -0.02 -0.37 -0.37 -0.45A: -0.28 -o. 17A0 -o. 19 -0.04 -o. 23A1 -o. 29B9 0.96 0.37 099 0. 19 0.60 0.01 0.57 0.64 0.28 093 0.80 0.30 0.02 0- 9 5 0.31 0.14 0.85 0.92 0.91 0.36 0.21 1. 20 1.36c 1.30 1.84 1.00 1.08 1-33 i. 27 i .04 1.24 1.42 i .12 i .09 1-37 1.30 1.66 1.48c 1.07 1.32 1- 3 3 1.08 1.26 1.16 1-34 I.56: I .OO 2.17 I 05 i .02 IIS 2.28 1.01 No. 200 142 207 206 205 204 202 201 199 198 193 192 190 180 160 155 154 143a 143 203 197 196 195 194 191 189 188 187 186 185 184 183 182 181 179 178 177 176a 176 175 174 173 172 171 170 169 168 167 166 161 159 158 i57a 157 156 150 149 148 143e 143d 143c 143b 165 164 163 162 153 152 151 147 146 145 144 R ti3-55: in.78: 15.89 10.29 1306 12.09 11-34 12.65 16.51 15.84 12.32 14.48 12.57 n.31: 14- 75 14.42 12.60 I5-36 13- 3 2 12.78 14.62 12.75 14.81 15.09 15- 7 4 16.28 15.24 n. 18 12- 5 3 10.60 12.51 16.29 16.54 16.30 15.22 11.69 12.04 12.54 15- 27 12.09 15- 7 9 13.38 14- 7 5 15 04 14- 9 8 16.19 15-34 15-56 14- 3 5 16.29 16.61 15.00 15-63 16.49 15.96 16.07 13- 52 15-86 15-60 16.07 15-94 11.23 14.79 16.55 16.24 15-47 15- 5 2 10.79 11.05 15-33 1517 16.09 14.99 10.56 pg 13.98 11.30 14.65 10.44 13.07 12.22 13-75 10.22 13 05 14.41 12.08 12.75 14.08 12.84 13-85 14.67 10.40 1500 12.20 12.52 12.68 15 05 14.48 14.62 12.31 11.93: 1389 12.28 14.61 I3-38 14.02 14.10 14.40 14.84 14.32 14.44 12.80 15.00 10.97 12.76 1503 14.48 1436 14.64 14.20 13-37 10.12 14.58 14.41 n 30 1316 14.67 14.96 13-41 12.12 14-51 14.41 14.36 13.40 n. 14 13.72 n.25 14.72 14.01 14- 9 5 14.69 14.08 13- 91 14.72 14-59 14-37 14.67 14.32 12.02 157 -0.07 -0.33 -0.16 -0.03 -o.62:d -0.15IA0 •o.oid -0.45I -0.09 -0.19 -0.27 -0.34: -0.37A0 -0.25 -0.35A0 -o. 20A0 0. 01 0.50 0.67I 0.00 0.96 0.79 o.86[ 0.13I 0. 95 0.03 0.54 0.73 0-99 0.14: 0.83d 0.63 099 0- 97 0.15 0.44CÍ, Go 0.02 0.64 0.92 0.54 0.78 0.79 0.90 1. 22c 1.27 1.24 1. 12I 1.24 1.07 1.46 1.18 1.58 115 1- 54 1.27 1-43 1.09 1.28 1.19 1-35 1.63d 1-33 1-54 1.44 1.19 115 i .11 2.12 ' * 2.18 1-35 1.88 1.87 1.63 194lApJ 94. . .55C No. 208 209 226 224 223 220 276 260a 240 239 230 229 228 227 225 222 221 219 218a 217 216 215 214 213 212 211 21G 266a 261 257 256 252 250 249 248 247 246 245 244 243 242 241 238 237 235 234 233 232 231 218 275 269' 268 267 266 265 264 263 262 260 259 258 255 254 253 251 280 279 274 273 271 270 278 277 272 CATALOGUE OFSTARSINMESSIER46,50,ANDNGC2324*—Continued © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 15-26 14.61 15.29 16.16 14.01 14.20 15-62 15.84 13-99 15-65 16.41 16.16 12.16 13.90 14.29 16.00 15-21 15-87 14.64 12.68 14.88 13-88 13-88 15- 71 14.88 15.ii 14- 75 13- 23 12.88 10.91 16.23 14.81 15-27 11.96 15-28 14.19 13-37 15.64 15-83 1312 13-25 14.94 14.06 I5-78 ii .19 14.21 14.02 15.98 11.05 13.09 10.88 il. ii 15- 63 12.81 13-36 14- 93 I5-8i I3-36 16.03 13 '61 12.82 15-54 15-79 I3-36 16.34 13.58 16.59 15-63 10.82 16.07 15.82 15.62 I5-98: 13-88 16.19 k pg 14.68 14.60 12.38 13- 74 14.25 14.70 13-87 12.72 13-47 14.06 14- 23 13-26 12.84 13.67 14.00 14- 40 14.20 14.56 13.70 13.84 I3-36 13-63 14- 52 13.98 1317 14.78 1396 13-35 14-59 13- 82 14.32 14.80 1415 12.10 13- 54 13.48 14.60 14- 92 12.95 13- 49 13- 32 12- 79 14.56 11- 5 13-54 13-47 I382 II .2Ó 13 04 II.52 14.48 II S© 14.60 14.99 12.38 13-95 1503 14.49 ii .10 14.68 14.47 14- 5 0 14.69 13- 5 7 14.41 14- 5 9 13- 3 4 II .22 13-22 15.00 14.08 13.29 12.80 14-51 9.98 -0.22 -0.04 -0.03 -0.14 -o. II -0.07 -0.36 -0.21 -0.34 -0.41 -0.28 0.00 0.16 0.96 0.77 0.92 0.88 0- 93 0 65I 0-55 0.25 0.36 o.53d 0.41 0.82 093 0.04 0-94 0- 94 0.81 0.87 o. I7d 0.52 0.36 0. 67 0.05 0.85 0. 3 1 I 0. 0 2 1.22 I o. 14 0.32 0.02 1- 9 7 I 05 1.12 I 1.17 1. 29:1 1. 60 i-35d 1.20 1.56 I 13 1.16 1.89 2.18 1.12 1- 43 1.14 1 .081 1.08 1.23 1.24 2.15 1. 22 2.16 115 1-35 i .12 i 13 1.19 1.12 1-39 i ■31 1.03 337a 336 335 334 333 331 330 329 328 327 326 324 323 322 320 337 332 325 321 319a 319 318 317 315 314 313 312 310 309 308 307 306 300 342 341 340 339 338 346 345 344 343 316 311 305 304 303 302 301 No. 353 349 348 347 352 351 350 296 299 298 297 294 293 292 290 295 291 289 288 287 286 285 284 283 282 281 GALACTIC CLUSTERS67 16.72 15-24 15-86 12.48 12.99 16.12 12.43 15- 9 4 16.21 16.15 12.16 13- 3 6 13-34 14- 85 12.22 12.91 16. ii 14-55 14- 9 14.47 14.09 13 09 16.16 16.25 14- 0 3 16.29 1396 15- 8 3 14.10 10.79 15-50 14.60 15- 91 10.55 14- 3 6 15-27 14.60 14.81 15.65 16.27 13.67 11.63 12.78 11.52 13-91 15- 5 8 14- 6 5 16.22 16.16 14.01 16.04 15-58 1506 14.14 15-63 1507 14.30 15-17 16.01 10.20 15-27 12.23 13.87 13.51 1306 12.86 16.02 13- 32 12.54 13-80 iS-8o 14.04 IS 04 15- 57 14- 73 Messier 46 'pg 14- 37 13-78 14.00 14.56 14.42 12.53 13 08 14.84 12.54 14.61 1502 14.08 12.16 13.27 13-75 13-66 12.99 14.50 13-66 12.53 12.33 13.95 13- 3 2 14- 3 3 14.80 13.64 14.29 13- 4 7 10.97 1499 13-39 11.98 11.80 13-75 13-75 ii .10 14.38 13.58 14- 3 5 13- 8 3 13.42 14- 5 3 14.41 13- 9 1 14.64 14.82 13-66 13-50 12.88 14.83 13.67 14.80 14.12 13-38 14.46 14.06 14.36 14.76 13.85 10.26 1317 1413 12.32 13-33 13 05 14- 73 15- O 12.76 12.67 14.26 13-22 14.52 13- 78 14- 54 13- 95 -o.o6dB9 -i.14 -0.09 -o. 19 -0.22 -0.35 -o. 10 -0.28 -0.31 -o.3id ■0.5 -0.09 -o. II -0.42 099 0.87 0. 0 0 0.09 0.02 0- 4 3 o. 10 0. 58 0.77 0.72 0.39 0.49 0- 9 71 0.92I 0.16 0.35 0.84I 0.77I 0.74 0.17 0.34 0.94 0.76 2.16 1.44 1. 28 1- 3 3 1.19 2.17 0.81 0- 45 i .02 1.19 2.16 1.83 1- 4 5 2.00 0.70 1. 41 0.18 0. 32 0.39 0.58 0. 26 0.78 i. 12 1-39 1.12 1.17 1-39 1- 4 5 1.92 0.78 1-52 1.24 1.17 i .01 1.25- 1. 28 1.03 1. 29 409 408 405 404 403 402 400 411 407 ¿06 401 399 398 397 396 395 420a 416 415 414 413 412 410 394a 394 393 392 391 390 423 422 421 420 419 418 417 389 388a 388 387 386 385 384 424 383 382a 382 381 380 378 379 377 376 375 No. 374 373 372 371 370 369 368 367 360 354 366 365 364 362 361 359 358 357 356 355 363 R 14.00 16.23 15-22 10.49 16.19 1301 14.28 14.70 12.56 15-36 13.24 II. 19 13-20 16.36 15-40 I5.26 13-85 14.17 12.47 15-47 15 08 14.97 16.60 12.67 12.69 14.01 13-49 12.15 13-73 1315 13-91 16.02 13-40 12.80 15-47 15.31 II. 19 16.83 16.10 I5-8o 15-40 14.24 16.09 1311 15-86 16.66 15- 7 0 14- 3 3 14.40 13- 5 3 13.54 10.49 12- 4 4 12.77 11.24 1311 15- 3 4 14- 35 15-93 12.16 13.46 15-49 13- 39 15-37 11.40 14.86 12.95 13-57 10.38 13-70 15-63 12.56 15-79 12.78 13-83 m pg 14.79 13.29 13- 77 14.40 14- 15 13- 66 14.80 14.17 10.96 14 03 1307 13-80 13.78 12.61 12.63 13-36 14-39 14.12 1413 14- 5 5 12.31 12.95 13-62 11-75 14- 37 12.24 13 06 13- 2 3 14- 03 11.66 13.76 13- 44 ii .41 14-75 13.29 14.87 13-10 14.36 14.67 14.50 14-54 14.88 13.85 13.24 14.58 14- 5 4 13- 8 2 13 00 14.61 1378 13-26 10.76 10.90 12.63 11-33 13-23 13.98 13.83 14.46 12.24 13-45 14.05 13-34 14.38 11.84 14- 39 13- 49 14.36 12.51 14- 56 12.76 12.97 13.38 10.32 13- 47 -0.27 -0.09I -0.12 -0.08 -0.44 -0.02 -0.30 -0.47 -0.16 -0.56 -0.09 ■0.47 -0.06 -0.14 -0.07 -o.37d -0.08 -0.13 0.48 0.23 0. 19 0.14 0.92 0.96 0.29 o. II 0.84 0- 43 0. 25 0.05 0-39 o. II 0.86 i .00 1. ii 1- 43 i 05 i .40 2.00 i .08 0- 54| 1.99 2.05 0. 51 0.62 0.271 o. 14I 2.50 1.27 1.96 i. ii 1. 28 1- 43 1.30 i. 21 0.52 0.01 0.05 1. 28 2.12 o.99d 0.47 0.21 0.05 0.02 i .09 0.36 0.19 0.06 1-54 136 1.47 l.44d 1.27 1.23 194lApJ 94. . .55C 68 JAMESCUFFEY No. 442 441 440 439 438a 438 436 426 437 435 434 433 431 430 428 427 425 424a 429 426a 432 47 30 46 45 44 43 42 40 38 37 36 35 34 33 32 31 41 39 22a 20 19 18 17 15 14 13 12 11 10 29 28 26 25 24 23 22 21 16 27 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 4 3 9a 9 8 6a 6 2 7 5 CATALOGUE OFSTARSINMESSIER46,SO,ANDNGC232i*—Continued 15-52 14.22 14.68 15-63 15-95 10.68 10.30: 16.19 16.17 14.89 15-60 15-57 1519 12.40 13.90 15-37 15-82 16.30 15- 6 0 15.34 17.70 12.30 13- 58 1389 10.57 14.28 13-77 12.69 1502 15-85 12.30 11-33 15-49 17.07 13-45 1514 17-47 12.35 15-81 15.76 12.32 16.15 10.86 12.05 15.58 12.53 11.90 12.02 12.97 15-21 10.99 13-65 13-75 1506 11.05 16.56 16.24 12.32 16.74 11.89 14.67 13-60 14.91 14- 59 1301 15-29 9.67: 9.09: 9.10: 7.9: 9.80: *pg 1316 13-78 14.06 14.68 14.49 13-97 14.40 15.01 1413 14.08 14.48 14.29 12.66 13-57 11.80 14.46 ii .31 12.50 14.38 10.89 12.96 12.40 11.66 10.91 15- 1 4 14.98 12.23 14- 9 9 14.69 14- 43 13.69 13-40 12.45 14-23 14.79 12.20 ii.15 14.47 1502 1311 14. ii 10.58 12.07 10.15: 14.85 14.82 12.56 14.67 13 ■59 ii.71 14-35 14-37 ii .81 14.05 1317 14.10 13.92 12.73 14.21 12.19 13- 32 10.48 13-32 14.28 9.65: 8.95: 8.85: 9.60: 7.66: -o. 26 -0.24 -0.85 0.44 0.71 0. 76 o. 2Ó: O.25 0.71 0.47 0.83 O. 10 0.69 0.43 0.13 0.78 o. 24 o. i4d 0.09 0.91s 0.08s 0.62s 0.43s 0.28s 0.37s 0.24s O.IOS 0.34s 0.28s 0.15:5b 0.02:5 o. 14:5 0.25:5 0.3:5 0.90 0.33 0.96 0.94 0.8IS 0.67s O. IIS 0.86s 0.26s 0.73s 0.09s 0.59s 0.79s o. 18s O.IOS I .12 1.42 1.26 I .025 1.03s 1.03 1-57 i. 27 1.79 1. 16 1.52 1.09 1.48 1.78 1.47c I-75s I-13s 1.06s 2.05s 1-93 No. 460 456 454 453 450 463 462 461 459 458 457 455 452 451 449 448 447 446 445 444 443 90 97 96 95 94 93 92 91 89 88 87 86 84 80 81 63 60 49 48 85 83 82 79 77 69 68 67 66 65 64 62 61 50 78 76 75 74 73 72 71 70 59 58 57 56 55 54 53 52 51 12.66 13-35 16.26 15 •10 14.86 15-95 15-09 15-90 15- 52 14- 35 16.20 1305 11.80 TO.20: 14.94 16.05 10.87 12.81 13-20 15-85 15-53 13- 94 16.38 14.68 11-59 14. ii 14.60 1312 12.22 13-04 16.co 15.48 11.74 12.25 10.10: 14.49 12.62 15 •18 12.93 14.56 15-10 15.66 10.89 12.32 15-58 II .31 13-80 16.12 13-61 13-04 14.16 15.86 15-76 16.10 1505 1511 15-24 13.50 11.07 12.66 16.28 16.01 16.35 1413 12.84 16.17 15-53 12.88 10.78 15-31 Messier 50 Messier 46 9.98: *pg 14.09 12.56 13 19 13.42 14.36 14.67 14-33 14.80 14.58 13.72 14-89 14- 53 1348 13.09 11.52 1501 13.98 11-55 13- 40 13-77 12.81 12.02 12.69 14-73 13-22 14.48 11.47 12.01 12.50 ii .00 14.64 14- 3 1 13- 8 0 12.26 14.27 14. ii 12.06 10.90 14.83 12.75 13.76 14.74 14.42 14- 5 1 14.16 11.30 14.40 11.67 13- 7 14.83 1338 1501 12.65 12.86 13-10 13-79 14.78 14.66 14.80 14.12 12.44 14.91 14.71 13-52 12.61 1502 12.54 10.52 9-75: 9.60: 9-75: -0.04 -0.41 -0.18 ■0.36 o. 10 o. 16 0.74 0.77 0.76 0-94 0.63 0.46 0.28 0.27 0.24 0.80 0.50: 0.69 0.36 0- 9 7 0.22 0.80 2.84 1.28 1.10 I-3I i .00 0.17 0.61 o. 18c 0.23 0.23: 0.79 0.34 o. 26 0.68 0.78 1- 37 i .00 1.27 1.83 1.07 1.03 1.19 1.44 1-37 1.30 1.52 115 IIS 1.18 i. 12 1.30 1.19 04 45: 83 31 35 04 70 06 o8d 71 20 34 37 29 23 13 16 145 144 143 142 141 140 139 138 137 136 135 134a 134 133 132 131 130 129 126 480 476 No. 128 127 125a 125 124 122 121 120 479 478 477 475a 475 474 473 472 470 123 119 118 117 116 US II4 US 471 469 112 111 no 109 108 107 106 105 104 468 467 466 465 464 463a 103 102 101 100 99 98 14.44 1301 16.00 10.5s 12.77 14.48 15-25 16.17 16.07 16.40 12.50 17-65 12.25 15.24 1317 11.66 16.08 12.94 15-50 ii-51 15-80 16.66 14.85 1513 16.13 15-15 13-65 14.02 12.75 12.16 13-51 12.25 14.69 12.78 12.05 15- 9 8 14. ii 13.09 11.82 14.22 13-62 16.23 13-38 14- 5 2 12.89 11.88 14-50 17.20 12.36 14.98 15-30 11.65 16.34 13-54 15-23 16.05 13.04 15-90 17.01 15.01 12.88 10.99 16.06 16.15 12.52 15.42 14.42 12.41 16.71 m Pg 14.62 13-68 11.36 14.68 10.44 10.58 13-83 14.40 14.71 IS 04 12.39 14.62 12.27 14-30 1302 11.38 12.84 14-52 14.40 ii .20 14- 4 5 14-54 13- 5 8 14- 0 7 14.70 14.09 13- 5 5 I3-36 11.48 12.35 13 06 12. ii 13-75 12.42 11.50 14.65 13-61 12.66 11-45 13-45 12.71 13-24 15-03 13.63 12.57 11.62 14.71 12.24 13-94 13.56 11.74 14- 93 14.29 1509 13-75 14.60 1317 14.67 14.02 13- 12 ii. 22 12.59 12.70 14.60 14-43 14- 73 13- 79 12.44 14.65 m. r —0.02 -0.09 -o. 24 -0.23 -0.07 -0.03 0.76 o. II 0.65 0.85 o. II 0.15 0.28 o. lod 3 03 0.94 0.31 o. 10 0.40 0.66 0.68 0- 45 o. 14 0.94 0.36 0.55 1.65 1.32 2.19 i .46 1-45 136 0.50 0.43 0.37 0.77 0.38 0.67 0.12 1.56 1.10 1.26 2.21 1.06 0.89 0.32 0.26 0.75 0.37I 0- 9 4 1.27 1.06 1- 43 0.34 0-99 0.99 0.63 1-33 1.20 2.49 1.04 1.74 1- 4 11 1.38 i .92 1-55 1.30 1-33 2.06 194lApJ 94. . .55C No. 201 200 198 197 196 199 195 194 IQS 192 191 190 189a 189 188 184 183 187 186 185 182 181 180 179 178 177 176 175 170 174 173 172 171 169 168 167 164 163 162 IS© 166 165 161 160 154 151 149 148 147 146 159 158 IS? 156 155 153 152 CATALOGUE OFSTARSINMESSIER46,50,ANDNGC2321*—Continued © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem ,14.48 ! 14.26 TÓ.59 16.28 14.03 16.06 12.98 13.78 15-65 16.30 16.51 14.80 13-39 15.96 I5.63 1509 15.48 15-95 14.22 14.85 13.72 12.63 15-91 12.36 11.59 14.64 14.28 15.48 16.18 15-52 1511 17.28 13-82 I3-38 16.27 16.28 15.02 15.24 14.65 14.25 16.20 11.84 15-73 16.47 15.40 12.78 10.50 14.22 15-59 15.85 10.45 15.48 12.28 15.24 11.84 15-93 16.08 15.40 14.68 15-95 12.14 15.96 16.48 14.65 12.71 16.12 15.64 10.52 12.54 10.98 12.61 m 9.40: 9-55: Pg 15.00 I3.4O ISIS 14.28 14.86 14-35 15.15 14- 5 9 13- 2 3 15-20 I3.8l I4.O2 14.88 I5.l8 ISIS I4.4I 14.64 12.71 12.22 13-37 14.62 14-53 12.16 11.52 13.78 13.75 14.42 13.91 14.92 1476 14- 31 1503 12.86 1329 1495 14.04 14.08 ii .41 1408 13- 73 14-56 1502 12.72 14-74 14-35 1455 14.62 10.30 12.09 10.30 14.60 12.24 14.30 11.50 14.77 14.56 14-62 14-43 13.72 12.18 11.88 10.40 1469 14.30 14.00 11.02 12.61 14.87 12- 34 15.09 13-22 6.80: 9-5o: — O.I9 — 0.09 1 o. 201 O.3O 0.38 0-45 0.24I 0.79I O. 21 0.21 0.21 O.16 O.76 O.82 0. 41 0.66 0.27 0.60 0.98 0.96 0.09 0.43 0.57 0.52 i 951 I.36 1. 28 1.44 0.06 0.20 o.is:d 1.38 1-33 0.88 0.04 0.34 •Si 1.16 094 0.97 0.96 0.05: 1.46 1.17 1-45 1.05 0.12 0.36 0.26 1.04 2.13 0.65 o. 10 0.27 1.23 1.16 2.60: 0.04 i-391 1-461 1.27 2.18 1.25 1.50 2.42 07 06 86 97 20 53 20 IS 255 252 251 250 247a 247 254 253 249 248 247b 246 245 244 243a 242 240 239 243 241 238 237 236 235 234 233 232 231 230 229 228 227 226 225 220 No. 224 223 222 221 219 218 217 216 215 212 214 211 209 206 213 210 208 207 205 204 203 202 GALACTIC CLUSTERS69 16.07 1449 13.46 1549 15.36 13.89 15-92 14.06 14.40 1510 15-55 13.64 15.89 15-45 13-81 11.80 13.40 1593 13.48 14.68 1581 15.64 12.91 15.29 16.69 15.96 17.14 16.09 15-88 15.88 16.51 14.46 16.37 12.16 12.92 13 01 13-77 15-57 13.40 12.15 16.21 16.50 16.41 16.40 10.80 14.89 15-70 13.81 16.04 13-34 15.57 14.65 12.70 14.58 12.91 12.68 14.61 13.90 16.34 15-28 13-54 1302 15-53 15-67 10.97 1568 13-88 15- 6 14.71 ii.18 14- 95 13.99 12.49 Messier 50 NGC 2324 "pg 14.98 13.64 1405 14.28 15-43 13 05 14.40 13-50 14- 93 1503 13- 54 14.12 14.66 1501 13-53 14-65 10.93 13.98 14.61 13-59 13.07 14.71 13-61 14.89 14.26 14.02 14-93 14.60 14-23 1502 IS 04 10.28 14.04 11.24 12.91 13.34 14-53 12.88 ii .91 14.09 14- 7 3 14.85 14.90 10.50 14.18 13.24 14.86 13- 3 5 14.71 14.49 13.91 12.42 1392 12.45 ii .69 13-51 1506 13.89 14.40 14.72 13.43 13.32 12.88 ii .19 14- 7 13- 45 14- 54 14.02 ii .00 13- 94 13-31 12.15 93 —0.22 -0.05 -0.16 -0.08 -0.06 0.33 0.17 0.54 0.14 0.52 0.51 0.64 0.00 0.87 0.44 0.33 0.98 0.70 o. 10 1.44 3 08 312 0.42 1.64 0.43 0.52 0.24 1.24 1.20 0.30 2.05 I 03 1.22 1.07 1.16 1.28 1.65 1.49 0.84 0.46 1.88 1.68 1-33 o. 71 o. 10 0.74 0.28 0.66 1.04 2.12 0.46 1.77 1.50 0.99 0.72 0.39 0.88 1.56 1-33 0.81 0.14 1.08 0.22 O.43 0.91 0.69 1.28 0.68 0.34 0.18 2.24 1.12 1.01 308b 308a 308 307 301 306 305 304 303 302 300 298 299 297 293 296 295 294 292 291 290 289 288 287 286 285 284 283 282 280 279 278 281 277 276 275 274 273 No. 272 271 270 269 268 267 266 265 264 263 262 261 260 259 258 257a 257 256 40 37 36 35 45 41 39 38 34 47 46 44 43 42 33 32 13-41 15-82 15.24 15-80 15-38 15-91 15 •10 15-52 13-30 13-55 16.06 14.90 16.02 15-45 16.21 14.58 16.61 15-74 14.74 1587 14.05 15-66 1307 15-67 11.84 13 04 11.24 1575 11.46 14.76 11.39 1517 15.78 12.38 14.19 13-20 15-77 15-61 14.46 12.91 1595 16.08 16.03 15.89 15-24 13-26 1333 16.13 15-91 16.16 12.35 1581 12.39 1539 16.31 ii .61 14.19 13 01 13-60 14.94 16.38 15.ii 14.86 14.66 15-33 15-50 16.24 13.98 12.28 17.04 15.81 14.89 "Pg 15-25 14.82 12.85 15- 32 14.94 1510 1510 1508 13.29 1348 1518 14.65 1505 14- 3 0 14.08 13- 6 8 14.75 14.96 14.64 14- 57 13.89 14.36 10.52 14.68 11.76 12.81 11.46 ii .01 13-81 14.94 13-51 14.52 ii.13 14.29 12.26 13.11 14.69 13-66 14.64 11.38 14.88 13-68 13.96 14.56 14.40 12.44 13-26 14- 5 5 1503 14.81 12.48 12.34 14.74 14.46 13- 68 12.94 11.42 14 •88 1332 14.00 14.96 14.09 13-95 1376 14-31 14.36 14.87 13.29 12.14 14.29 14.69 14.19 -0.13 -0.22 0.42 0.561 0.70I 0.16 0.44 0.57 0.28 0.59 0.01 0.07 0.88 0.50 o. 16 0.25 0-49 o. 10 0.99 0-97 0.99 0.08 0.23 0.81 0.45 0.95 1.91 0.26 0.68 0.88 0. I2d 1.30 2.93 2- 5 0.80 0.97 0.09 0. 821 0.07 I 0.93 0.05 1. 26 1.08 0.84 0.51 0.07 0.19 0.28 0.91 1- 53 2.40 0.94 1.07 2.07 1-33 1.36 0.90 0.69 1. 10 1-35 i .07 1.43 0.14 0.70 1.42 i .02 i .02 1.14 1.37 2-75 i .12 30 194lApJ 94. . .55C 70 JAMESCUFFEY No. 127 ios 103 101 100 109 108 107 106 104 102 126 125 124 123 120 118 117 116 US 114 113 112 in no 122 121 119 SOS 65 60 85 84 83 81 69 68 67 66 64 63 62 61 49 48 90 96 95 94 93 92 91 89 88 87 86 82 80 71 59 53 52 51 50 56 55 54 99 98 97 79 78 74 73 72 70 58 57 77 76 75 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 2S CATALOGUE OFSTARSINMESSIER46,50,ANDNGC23U*—Continued 14. 26 1300 13.64 14.84 15-43 10.50 15-78 16.12 15.04: 16.19: 15- 63 13.98 16.37 15- 95 14.68 15.34 14.26 12.80 13- 65 13-30 11-95 14.72 15.04 16.26 15.69 15.78 1504 14- 39 13- 45 13-43 14.86 I5-32: 15- 81 15.23 14- 59 14.69 15-62 14- 65 14.26 I5-38 13.96 16.02 15-33 14.56 15.46 12.65 13- 63 15-72 15.46 15- 4 7 13.89 13- 9 9 14- 31 14.71 13-68 1518 15.78 16.37 16.33 15.40 1413 15- 85 1305 14.79 14.62 15-87 14.81 16.08 14.24 14- 4 3 15-57 13-88 14.81 15.48 1566 15-73 13.76 14.24 1311 15- 4 5 13.92 14- 43 'PS 14- 30 13- 23 14- 59 1464 14.46 10.37 1512 14.76 1516 14.91 15- 3 14- 7 15 00 15- 12 14- 34 14.92 15-39 12.82 1390 13- 5 11-34 13-20 13-21 14-74 1496 15.34 14.65 14.10 13- 5 11.62 14-73 14.41 1311 1512 14-54 14-35 15- 21 1500 14.04 14- 3 15 03 12.41 12.30 1463 1508 12.71 14.40 14.63 13.78 14.48 15- 45 1539 14.22 12.98 12.69 1529 14.68 15-38 14.09 1519 14.74 15.28 1299 14.40 14.58 15- 3 0 12.64 14.46 14- 5 3 14-43 14- 3 5 13.45 13.29 14-56 14.97 1506 1318 14.97 14.32 1395 1516 13-88 -0.361 -0.09 -o. 10 -0.25I -0.25I -0.04 -0.23 -o. 10 -0.36 -0.09 -0.08 -0.24 -o. 12 -0.08 -0.03 0.20 0.97 0.43 0.30 0.73 0.44 0.39 0.13 0.13 0.66 0.561 065I 0.32 o. i8| 0.79 0.27:0 0.61 0.29 0.50 0. 51 0.04 0.57 0.38 0.66 0.83 0.39 0. 08 o. 7od 039 0.50 0.98 0.46 O. 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II 0.38 0.41 0.23c 0- 43 0.24 0.43 0.73 095 0.25 0.51 0.60 0.39 0.04 0.57 0.47I 035I 0.92 0.00 0.57 1.67 1- 581 1-52 i.81 1. igx 1. 18 2.36 1-44 1-33 1.16 1.04 i .11 1.25 1.25 No. 156 155 154 153 149 144 167 166 165 164 163 162 161 160 159 158 157 152 151 150 148 145 143 142 141 140 203 202 200 175 169 168 147 146 139 138 135 186 185 184 183 182 181 180 179 178 177 176 174 173 172 171 170 137 136 134 133 131 130 129 201 195 190 189 188 187 199 197 196 194 193 192 191 128 204 198 s 29s 19s 18s 17s 4 3S 15-31 1392 14- 53 16.44 1516 16.07 14.62 16.04 15-86 16.64 14.29 16.37 15- 9 4 14- 9 3 16.22 15-63 14.58 14.46 13- 30 13.46 16.18 12.65 1518 14.44 14.91 16.53 14.19 14.78 14- 7 7 I5-56 15-55 11.88 1506 I3-78 14.10 15 05 13-85 15.21 14.21 16.15 16.32 16.19 15- 56 16.00 15- 9 4 14- 7 3 15-99 16.51 15- 9 3 14.08 15-71 15-73 1576 14.66 13-79 14.86 16.56 15-26 16.49 13- 79 15-81 12.90 15.46 15-29 15-76 12.24 15-71 15.58 15 10 14.19 14.76 14.47 14- 7 7 15.56 1539 14.56 14.71 15-77 15-71 15-68 16.10 12- 37 NGC 2324 'pg 15- 0 14.27 15- 40 14- 56 I5-36 14.74 15- 2 8 13- 9 9 15-52 15- 3 4 14- 5 7 12.79 15-45 13- 79 1504 13-94 14.47 13-39 13-63 12.76 14.89 14-37 12.34 15-59 12.53 1509 15-07 12.00 14- 35 15-37 15-47 15- 59 1500 1463 12.31 14- 3 1 15- 3 9 14.66 IS 18 15 04 14- 5 4 14-93 14-51 14.89 1507 15-32 15.46 12.80 14- 5 5 14.48 14 03 14.65 12.79 14.64 14-35 1507 15- 3 1 11-55 14- 9 5 14- 9 5 14.74 12.05 14.36 1396 14.61 14-59 1509 14.72 12.63 15.13 11-93 1518 1507 1398 14.61 14.98 15- 3 1 1514 13.72 1506 15 06 1518 -0.01 -0.09 -0.17 -o. II -0.14 -0.15 -0.04 0.26 0.60 0.71 0.83 0.59 0.64 0.32 0.29 025I O.S9I 0.54I 0.921 0.90 0. 72 0.78 0.85 0.60 0.56 0.47 o.4S| 0.61 0.49 0.76 0.52 0.30 0.36 0.85 0.60 0.36 0.77 0.32 I 0.69 o. 27 0.39 0.29 0.63 0.24 0.44 0.53 0.51 0.72 0.88 0.73 0.33 0.91 0.36 0.65 i .02 0.62 0.63 0.14 0.42 0.49 0.41 0.67 1.04 i -45* 1.971 1. 26 i.881 1.36c i 13 I-73 I 1-34 1.88 i .40 05 46 88d 19 64CL 67CÍ 10 53 No. 240 220 255 254 252 250 249 248 247 246 245 244 243 241a 241 237 236 230 222 221 219 209 208 253 251a 251 242 24id 241c 241b 239 238 235 234 233 232 231 229 228 227 226 225 224 223 218 217 216 215 211 210 207 206 214 213 212 205 28s 20s 21S 273a 27s ios 20sa 26s 25sa 24s 23s 22s 16s 13s I2S ns 25s 15s 14s 6s 7s 9S 8s 5s R 12.51 1501 15-72 15-91 16.14 13-31 I5-56 13-31 15-91 15-86 12.97 16.29 15-70 16.25 13-99 15-57 15- 37 14.29 15-39 13-56 11.88 16.62 14.01 15.69 15.96 13-37 12.23 11-54 14- 9 3 13- 2 5 14.64 15.48 15-94 13-20 15-74 15.46 14.87 15-34 15.42 13.92 16.13 16.21 15-85 13-58 15-72 14.80 14.29 13.67 13-55 17.17 12.63 13.90 13.84 ISIS 1518 1343 1500 13 09 15-63 16.15 1439 15- 9 16.23 1514 14. ii 15-47 15.46 14.12 13-33 I7-38 15.51 16.55 14.68 16.13 14- 95 15-80 13.42 1301 16.14 9.7: *pg 14 79 -0.04t -o. 26 -0.13 0.63I 0.88 0.12t 0.17t 0.90t 0.97t o.oot O.4: t O.32 0.70t O.gSt O.9I O.9I 0.70t O.84 O.75 0.52 0.57 0.68 0.47 0.66 O. 20f O. 22 0.72 0.79 0.15 0.51 o. i8| 094 0.23 0. 6 4 0.23 i •37I i .86t i .86t 1.25t 1.46t I.89 0. 6 9 117t I-83t i .00 I-25t 1.64 1.30 1.02 1.23 1. 26Id 1.31 1.01 1. 22 02 92 65 65 57 63 So 52 58 75 78