1964AJ 69. . 4 90E THE ASTRONOMICALJOURNAL principal objectivesofthestudywere: THE Harvardmaser-equipped60-ftantennawas can usethisdistributiontodeterminetheHicontent correlation withmorphologicaltypeandothercharac- and systemicvelocityofeachgalaxy. atomic hydrogen(Hi)ineachgalaxyobserved.We profiles similartotheobservedand(b)estimate motions, orientation,andangularsize,thevariations teristics ofthegalaxies. models; tousethesemodels(a)generateHiline of thepredictedHiemissionfromaseriesgalaxy galaxies donotappearaspointsourcestotheHarvard antenna. Wehavereportedtheseinvestigationsina the errorsthatresultfromfactobserved reduced results.SectionHIdiscussesthedetermination separate paper(Epstein1964). section concludeswithatabularpresentationofthe of theHimassesandtotalmassestimates; galaxies. SectionIVpresents statisticalsummariesof results ofallcurrentlyavailable 21-cmstudiesof College Observatoryissupported bytheU.S.NationalScience Foundation. * TheAgassizStationRadioAstronomy ProjectofHarvard Section IIpresentstheobservationalprogramand (2) TotesttheHiradiationdataforpossible (1) Toobtainthevelocitydistributionofneutral, (3) Tostudy,asfunctionsofassumedinternal © American Astronomical Society • Provided by theNASA Astrophysics Data System used tostudyatomichydrogeningalaxies.The investigated withtheHarvardmaser-equipped60-ftantennaand8galaxiespreviouslyelse- where. Hiemissionwaspositivelydetectedfrom3Sb,13Sc,andIrgalaxies;forthegalaxieswhich nitely tendtohavehighervaluesof911#i/L,i/91Z,and -26 2 S (10 W/M /CPS) S .10 “W/MVCPS. 493 1964AJ 69. . 4 90E 494 © American Astronomical Society • Provided by theNASA Astrophysics Data System + 400300200+1000-100-200 -300-400 -»-400 +500+600+700 EUGENE E Fig. 1(continued) KM/SEC KC/SEC KM/SEC (h) (g) (I) EPSTEIN c/> b S (10"26 W/M2/CPS) 1964AJ 69. . 4 90E © American Astronomical Society • Provided by theNASA Astrophysics Data System ATOMIC HYDROGENINGALAXIES + 100+200 Fig. 1{continued) KM/SEC KM/SEC KM/SEC KM/SEC (m) (j) (I) (k) 10.0 4.0 o 8.0 o? 0.0 2.0 « s o -26 s 26 2 s (10 W/m7cPS) (10- W/M /CPS) 495 1964AJ 69. . 4 90E 496 ,;K AT 0.20 ’ 0.10 a © American Astronomical Society • Provided by theNASA Astrophysics Data System Í-4-4—* i-i- 4-4500 4-1500 +200 EUGENE E.EPSTEIN * i'.t.1■, +300 +400 Fig. 1(continued) KM/SEC KM/SEC KM/SEC KC/SEC (n) 4-300 (P) (o) (q) +300 +400 z : 2.0 - 4.0 to. o S (10 26 W/M2/CP$) 1964AJ 69. . 4 90E © American Astronomical Society • Provided by theNASA Astrophysics Data System id 4- uj 6- O Q ce Q cn ¿ 8- £ I io- SE £ 12- c 14 - 16- +600 +700+800+900+1000 NGC 4486(E) ATOMIC HYDROGENINGALAXIES Fig. 1{continued) + 1200 KM/SEC KM/SEC KM/SEC KC/SEC (r) (U) (S) (t) 0 t-1300 + 1300 26 T 3.9 X10"W/M/CPS J L_ RELATIVE POSITIONERROR + 1400 0°.20 K AT- a 26 2 26 2 S (10“ W/M /CPS) S (10-" W/MVCPS) s ho w/m /cps) 497 1964AJ 69. . 4 90E 498 © American Astronomical Society • Provided by theNASA Astrophysics Data System (°K) 0.00 0.10 0.20 0.30 4-400 4-5004-6004-7004-800 4400 +500+600+700800 NGC 4456/4631 i r + 1000 f1 ■ *-'nr-l.. EUGENE 5 , ...r**,,» } UL CZZiLlZ-4I Fig. 1{continued) + 500 KM/SEC KM/SEC KM/SEC KM/SEC KC/SEC KC/SEC E (w) (w,) (V,) (v) 2 2 EPSTEIN + 700 + 800 -6.0 o £ 1964AJ 69. . 4 90E © American Astronomical Society • Provided by theNASA Astrophysics Data System ATOMIC HYDROGENINGALAXIES Fig. 1{continued) KM/SEC KM/SEC KM/SEC (z) (y) 2.0 ^ 4.0 f 6.0 I 0.0 8.0 ^ to Q_ co o 00 o 26 2 S (10- W/M /CPS). 499 1964AJ 69. . 4 90E 500 © American Astronomical Society • Provided by theNASA Astrophysics Data System OBSERVED DISTANCE(MINUTESOFARC)EAST(•)ANDWEST(O) OBSERVED DISTANCE(MINUTESOFARC)EAST(•)ANDWEST(o) OBSERVED DISTANCE(MINUTESOFARC)EAST(•)ANDWEST(O) (c) (b) EUGENE E.EPSTEIN (a) in NGC55,300,and3109.Abscissa: procedures aredescribedinAppendix width (seeSec.IIIB).Datareduction A5. sight. Theestimateduncertaintiesand line profile,uncorrectedfortheinchnation ative totheadoptedcentervelocityof Ordinate :radialvelocity(orfrequency)rel- of theplanegalaxytoline ter, measuredintheeast-westdirection. observed distancefromtheadoptedcen- the antennabeamandreceiverband- the observationsareindicated.Nocorrec- tions havebeenmadeforsmearingby the receiverbandwidth(ß)usedduring Fig. 2.Rotationalvelocitiesobserved 1964AJ 69. . 4 90E h eav b bav a f f 2-1 d c f c au i hav b d c a The Galaxy 55 3031(M81) 598(M33)* 3109 3034(M82) 224(M31*) 300 247 *10 4631 2403 4244 Holmberg II account fornonnegligibleopticaldepth,wehave is theareaunderlineprofilein(Wm~cps) 4214 *1613 if (7«1.Thevaluesoffusedarethoseestimated included thecorrectionfactorC,definedby 4449 LMC 628(M74) SMC values ofCinColumn27. 3109 andNGC4244havef>0.4;forf<0.4,Cwas estimating procedureandtheerrorsinobser- by Epstein(1964).Becauseoftheuncertaintiesin where 5isthedistanceofgalaxyinMpcand 5457(M101) 5194/5(M51) Sextans A *3428 set equaltounity.Theestimatesoffarelistedin only whenf>0.4(correspondingtoC>1.2).OnlyNGC vational data,weusedfincalculatingCfromEq.(2) radiation forthereasonspresentedinAppendixCl.To 6822* 4656 6946 224.VandeHulst,Raimond,and vanWoerden(1957). Notes forTableIIIappearbelowandonthefollowingpages, *2574 IC1613.AlsoobservedbyMiss VoldersandHogbom(1961). SMCandLMC.KerrdeVaucouleurs (1956). 5236 (M83) IC10.AlsoobservedbyRoberts (1962b). Column 26ofTableIIIandtheadoptedorderived X (km/sec).Wehavedisregardedeffectsofcontinuum NGC © American Astronomical Society • Provided by theNASA Astrophysics Data System *IC (1) cg Sc—/Ir II Sc/SBb df Type Ir Sei Sb Sb- Ir Sc Ir I Ir I Ir Ir I Irl Ir I Sc— Sc+ Sei Ir I Sc- Sc— Sc-f" Ir I Ir I Iri Ir II Sei Sc+ Sc+ Sb- C=f/[l-exp(-f)]; (2) (2) Notes toTableIII k k p cv 332?75 314.61 302.90 299.14 279.49 121.17 118.96 246.24 262.10 113.84 104.84 140.22 138.16 138.61 133.63 129.87 102.04 142.60 136.83 154.57 140.13 141.38 142.09 144.28 150.57 160.30 Table III.DataforgalaxiesfromwhichHiemissionhasbeendetected. 25.38 95.71 11 (3) l ATOMIC HYDROGENINGALAXIES cv k k -18.37 4-10.58 4-31.96 4-84.72 4-84.23 4-39.92 4-23.07 4-40.57 4-40.90 4-32.71 4-29.18 -75? 72 4-68.56P 4-72.41 4-77.16 4-78.07 4-43.59 - 3.32 4-11.66 4-59.78 -45.70 -31.33 —60.55 -79.41 -21.57 —32.84 —44.40 -83.54 11 b (w—Tí)o(Mpc)i (4) V V V V r r r 1 V X q n m r ab r r 26.7 26.4 27.6 27.6 27.6 27.6 29.5 24.3 24.2 24.2 26.8 27.6^ 27.6 27.6 27.6 26.5 26.7: 26.9 27.8 28.0 27.& 28.6 25.0 23.4° 18.4 28.1 27.7 18.8 (5) (6)(7)(8) CZ ae aa ah 0.72 0.69 3.3 3.3 3.3 2.2 0.69 2.3 3.3 3.3 3.3 2.2: 3.3 0.048 2.0 0.057 2.4 Jew 3.6 4.0 3.3 3.3 7.8* 1.9 5.2 4.2 0.48 3.5 e h k g m 0 D f 8 r q 1 db s 1 ac am 598.Mrs.Dieter(1962a).AlsoobservedbyMissVolders 3031,3034,and6822.MissVoldersHogbom(1961). SMCandLMC.ThecentroidsoftheHidistributionsdeter- IC342.Mrs.Dieter(1962b). 4631.MemberofUMaIIgroup(Sersic1960).Sersic’smodulus j 55,300,IC342,and3109.Humason,Mayall,Sandage 4ah p 5194/5.ThesecoordinatesgivethepositionofNGC5194. 6822.ApparentmodulusofSandage(1962)correctedfor 5194/5.MemberoftheM101group(Sersic1960).Sersic’s 628,2403,and4244.Roberts(1962a). 35e LMC.Feast,Thackeray,andWesselink (1961). 224,SMC,IC1613,598,LMC, and5457.Sandage(1962). 247.MemberoftheSouthGalacticPolegroup(deVaucouleurs 5194/5.Heidmann(1961). 35 57 84° * 628.Distancederivedfrom+780 km/sec[theIIiradialveloc- 59 54 27 4244.MemberoftheUMaIgroup(Roberts1962c).See 46 7.5:^ 86 60 84 75 75 31 9.67 35 27 8.20 2 1 hmb1 mined byKerr,Hindman,andRobinson(1954)areat«wbo Note y. has beencorrected(seeNoteq);theaverageobscurationis modulus hasbeencorrected(seeNoteq);theaverageobscura- km/sec/Mpc. galaxies andobtainedbytheaddition of300cos(J—55°)cosb ity correctedforsolarmotionwith respecttothelocalgroupof modulus. km/sec to+654km/sec]and a Hubbleconstantof100 obscuration bythecosecantlaw. tion is—0^29. the averagecosecant-lawobscurationforgroupmembers Sersic (1960)hasbeenmultipliedby1.11(Sandage1962),and (1959). 1959). Thedistancederivedfromtheapparentmodulusof -0?26. (SMC). =0535, ¿i960——68?5(LMC)andawso—0120ôigso^—72?5 (1956). (—0^25) hasbeenappliedtoobtainthetabulatedcorrected cdc ak af ah ag a aj 10.00 10.4:*' 10.48 10.12 10.91 11.55 10.5 : 11.14 13.68 10.74 8.7 9.74 6.19 4.33 9.20 0.50 9.47 9.90 8.80 9.71 7.85 2.668 9.21 8.65 ymQae cb r r 1 er r r -0^26 -1.3: 0.26 0.25 0.38 0.62 0.37 0.45 o!3Í 0.35 0.13 0.25 0.25 0Í60- 2 I 0.25 0.26 0.36 0.38 0.50 0.38 0.24 0.25 0.27 0.73 0.29 0.49 J ^y.cz,dc AWrv (9) -1^3 ap -0.05 (10) 0.10 0.06 0.06 0.17 0.12 0.40 0.29 0.03 0.06 1.03 1.23 1.04 1.03 &A 10 08 dc (10Z o)dimensions 0.17 0.43 6.7 O.OU: 0.21 0.33 0.17 0.08: 0.46 0.2 0.41 0.0076 0.049 0.093 0.019 0.96 0.27 3 0.098 0.082 0.013 2.3 1.6 1.7 1 1.2 1.6 1.0 (ID Zpg Optical daat aw aoaq ao,a(l aocw ,ao,aq a0 aitay ba az od 40X33- 300X180“-“ 83X53“ 23X23 35X26- 28X10 23:X3: 5X3’ 47'X9 9.3X8.6 35X14.4 29X15 197X92“* 20x18 720X640 12.0X12.0 20X20 28X28 8.9X7.4 10.1X8.7 18X2.9 10.6X10.6 13.4X8.5 16X8.0 11.0X8.9 14.5X4.1 19X4.4 14.4X12.6 14.2X9.5, (12) 501 1964AJ 69. . 4 90E bav a c c d f eav h h f 1 f au v u w hav ab ad x ac aa ae 2 ai ah ag af al am ak a an 502 247 224(M31’) *10 LMC 300 SMC 55 The Galaxy Holmberg II *1613 628(M74) 598(M33)' 3034(M82) *342« 3109 3031(M81) 2403 6946 5194/5 (MSI) 4656 4449 4244 4214 5457(M101) 5236 (M83) 4631 2403,HolmbergII,3031,3034,andIC2574.Membersofthe *2574 Sextans A 3109.Inderiving3TIfromEq.(3),wehaveassumedthat3109 3109.VandenBergh(1960). 6822- ^ 55,IC10,300,3109,and5236. Thesearethedimensionsgiven 6946.VandenBergh’s(1960)luminosityclassificationindicates IC10,598,628,342,2403,4244,and5457.Theintegrated y 4214,4449,and4656.MembersoftheUMaIgroup(Sersic SextansA.Arp(1961). SMCandLMC.KerrdeVaucouleurs(1955). 5236.DerivedfromthecorrectedHIvelocityof355km/sec 55.deVaucouleurs(1961b). 5194/5.Roberts(1962a). SMCandLMC.deVaucouleurs(1960b). 300.deVaucouleursandPage(1962). SMCandLMC.CalculatedfromtheasymptoticB(B—V) IC10.MeasuredbyPettit(1954)withanapertureof2Í3 598.Thisfluxisthevaluecorrected forsourcesize(Heeschen 5457.MissVolders(1959). 3109and5236.deVaucouleurs (1961c). ¿ 5194/5.Thisvalueisthecombinedmagnitudeof5194and 224.Heidmann(1961). is rotatingandseen“edge-on.” fluxes andHimassesofMrs.Dieter(1962a,b,d)Roberts Jkfpg~ —19.7.CombiningthisvaluewiththemgandAw average obscurationis—O^ó. M81 group(Sersic1960).Themodulusisthatof2403(Sandage of +387km/secindicates(w—3f)=28.O. values leadsto(m—M)~28.1.ThecorrectedVhi(seeNotet) values ofdeVaucouleurs(1960)andEq.(30) diameter. 1962). 5195. 1960) .Sersic’smodulushasbeencorrected(seeNoteq);the by deVaucouleurs(1961c)but, to makethemequivalent (see Notet)andaHubbleconstantof100km/sec/Mpc. the dimensionsofHolmberg(1958), multipliedbythefactor 1961) . (1962a,b) havebeenreviseddownwardby3.5%. P (1961a). 0 0 NGC © American Astronomical Society • Provided by theNASA Astrophysics Data System *IC (1) +0 +0 Main body (13) CV c cp cq 48p 32 47 18 23 19 lOcq 13 nebula b cb +0.77 +0.37 : bk cq cp cp bd cp bd bc bf be cq Entire 0.56 0.30 0.29 0.36 0.30 0.71 0.18 0.35 0.49 0.61 0.21 0.20 0.14 0.72 0.23 0.48 0.43 0.16 0.18 0.18 0.22 0.32 (14) Co' ac b s b bx cf bi +168 + 12 +561±50 +248±40 +210±50 + 70±40 -278±25 -343±12 +403 ±40 +220±30 +260db2 - 28±35 +491 ±30 +490±25i +206±50 +306±30 + 28±60 -189±15 —238=bl0 + 38±50 +247±30 +721±60 +265±60 +441 ±20 +275 +591±65 - 45 - 35±20 (km/sec) Voptical EUGENE E,EPSTEIN (15) Table III{Continued) ac ac + 56±5 +654±5 +161 +156±15 +131±5 +159±12 +137±5 +276 +145±10 —300±3 —347±7 + 95±30 +474±30 +204±10 +289±5 + 47±10 +325±8 —186±5 —236±3 +268±5 +530±15 +240±10 +403±10 +184±15 +660±30 +570±80 - 40 - 62±5 (km/sec) VhI Ftfl—TopticalAF* (16) aq ap ar bb ba au at as aw av ay ax az 55,300,and3109.Theobservedeast-westHidimension 5194/5.Thiscorrectionappliesonlyto5194. 224.TheHimajoraxisisatleast300'long(vandeHulst, IC10.Pettit(1954)measured a C.I.of+0.91through2Í27 6822.TheHidimensionalong thelineperpendicularto 5457.Mrs.Dieter(1962d).AlsoobservedbyMissVolders IC342.TheoverallHidimensions,correctedforantenna 598.TheoverallHidimensions,correctedforantennabeam IC1613.MissVoldersandHogbom(1961)statethatthe 224,598,and6822.Recentresults(inabstractform)of21-cm LMC.KerranddeVaucouleurs(1956)detectedHiouttoan SMC.KerranddeVaucouleurs(1956)detectedHiouttoan 5457.TheoverallHidimensions, correctedforantennabeam 1 for spiralgalaxiesobservedbyHolmbergandhimself). rotation curveinFig.2)isapproximatelyequaltotheoptical Raimond, andvanWoerden1957). magnitude systemwithEqs.(25) and(31)ofdeVaucouleurs beam broadening,are108'X85'(Dieter1962b). broadening, are145'X100'(Dieter1962a). dimension alonganeast-westline. 1.5 (determinedbydeVaucouleursfromacomparisonofdata Leiden antennabeam(half-powerwidth=34').Ifthe observations havebeengivenfor224(Burke1963),598 observed Hidistributionisabout6%broaderthanthe Holmberg’s opticaldimensions,thatis,25'X25'. beam patternandtheobservedHidistributionareGaussian, diameter aperture.Thisvaluewas convertedtotheHolmberg axis ofrotationisapproximately 28'(VoldersandHogbom average radiusofapproximately440'. average radiusofapproximately340'. assumed thattheoverallHidimensionsare6%greaterthan H idistributionis~12'.Toestimatetheopticaldepth,we then Eq.(A-28)ofSeeger,Westerhout,andvandeHulst broadening, are81'X73'(Dieter 1962d). (determined fromthemostdistantreliablepointson 1961). (Turner, Tuve,andBurke1963),6822(Burley1963). (1959). (1956) canbeusedtoinferthatthehalf-powerwidthof + 2 +184 + 44 + 93 + 3 + 57 + + + - 7 - 27 - 4 + 21 + 39 -103 - 79 - 16 + - 27 - 2 - 61 - 21 (17) 61 67 38 91 78 16 15 17 19 5 bh 210±20 500±30 230 256±20 240±20 190 120: 105±15 110 160±20 190±20 140±25 230±60 130±10 150±20 160±20 150±10 140±20 150±30 68 ±10 25±3 80±7 63 ±6 60±6 75±8 (18) (km/sec) df bg bg 310 230 bg 200: 220 230 125 130^ 130 115 120 130 160 110°^ 100 100: 170: (19) Vm 60«^ 80: 60 90 30 70: 70 75 bt bp be ci CW ct 43 h ant 20 cm ci 19 12 18 12 10 0.1 3.0 0.27 3.5°* 0.30*^ 0.14“ 2.1 0.69« 0.96 6.4 0.026 0.81 0.33 2.5 7.0°° 2.8±0.5 5.3 2.1 1.4±0.3 1.4 1.4 1.8 1.9 (109Ko) (20) (solar units) (21) 23 18 12 15 12 10 16 14 11 4 3 3 6 4b q. 8 4 4 8 5 6 2 8 2 9 7 2 2 5 y co’ Lg P 1964AJ 69. . 4 90E f a bk c bBT bi 1 k f eav d bh bf be haT k bd aa f bg 4631 4244 4656 4449 4214 300 *10 The Galaxy IC342.Pettit(1954)measured aC.I.of+0.95through LMC° SMC 247 224(M31*) 55 3031.Opticalradialvelocityfrom Munch(1959). *2574 3109 hj 5194/5.Thisvalueisthearithmetic averageofthevelocities 5194/5 (MSI) 3034(M82) Holmberg II 628(M74) 598(M33)« *1613 55.Thehalf-intensitylevelwastakenasone-halfofthe 5236.Pettit(1954)measuredaC.I.of+0.67throughan 5194/5.Thisvalueisthecolorof5194only(p.32,Holmberg 6822- 5236 (M83) Sextans A 3031(M81) *342g SMCandLMC.Theasymptotic(B—V)colors(deVaucou- h® 247.Pettit(1954)measuredaC.I.of+0.67throughan8Í8 6946 5457(M101) 2403 55,300,and3109.Themaximumvelocitiesforthesegalaxies ignored. was obtainedasdescribedinNotebe.(Pettitalsomeasured 2!27 diameteraperture;Eqs.(25) and(30)ofdeVaucouleurs according toMayallanddeVaucouleurs (1962). were determinedfromthemostdistantreliablepointson lines existintheverybright,smallnucleus(deVaucouleurs low Galacticlatitudemakestheusualextinctionformula of 5194and5195.Theaverage velocityis+444km/sec 8Í6 diameteraperture,thatis,anaperturewhichincluded have beentransformedtoHolmbergcolorswiththeaidof inappropriate. amplitude ofthelow-velocityshoulderinlineprofile corrections, beingunnecessary,werenotapplied. only thecentralportionofgalaxy.Thetabulatedvalue Eq. (30)ofdeVaucouleurs(1961a). leurs 1960),reducedbytheexcessesgivenSandage(1962), average valueforScgalaxies. Eq. (2)ofHolmberg(1958),withßsetequalto0.093,the [Fig. 1(a)],thatis,thepronounced asymmetricalpeakwas rotation curves(Fig.2)andnot(intheusualmanner)from C./. =+0.59witha0Í7diameteraperture.)Strongemission obtained byusingthecosecantlawforGalacticreddeningand on theHolmbergmagnitudesystem.Thetabulatedvaluewas the extrapolatedwingsoflineprofiles.Randommotion diameter aperture.Equations(25)and(30)ofdeVaucouleurs 1961a). 1958). Thecolorof5195is+0.91(Holmberg (1961a) andisuncorrectedforselectiveextinctionbecausethe (1961a) wereusedtoconvertthisvalue+0.61,the NGC © American Astronomical Society • Provided by theNASA Astrophysics Data System *IC (1) -2-1 bo bn bn dd bn W mcps) ^ 1.8db0.2 <1.4 <1.4 <1 5J0.6 <0.8 <0.8 <0.6 <0.7 <0.4 <0.8 <0.6 <2 <1 <1.2 <1.0 <0.8 <1.0 <1 z al 2: 2.8=h0.2 8.8±0.2 1.8zb0.2 5.7 26 (io- (22) 5c ad 2-1 ad ad ad 104 W m~cps ad ad ad bm bI 35.5 24.5zt2.5 bm 36.2 20.Ü2.0 21.5±2.1 18.1d=4.5 16.0=b2.9 12.8±1.5 Xkm/sec) 6.3±1.5 8.0±2.0 3.0±0.8 5.0±1.0 9.5±1.8 6.2±1.5 3.8±0.6 5.3±1.6 2.3d=0.3 5.7rfc3.0 5.6±1.1 6-^12 5.2zh2. l 7.9Ü.8 5.9±4.4 7.0=bl.4 24 fSvdV ATOMIC HYDROGENINGALAXIES (10- (23) 2 W m“cps“ 26 (IO- 38 22 12: 12 (24) Sy 2.7 2.4 2.0 2.3 5.0 2.6 3.8 2.4 3.1 2.2 8.4 3.1 2.9 1.6 7.1 7.4 1.2 1.9 1.8 Table III{Continued) l ) fSvdV e e 0.19 0.36 0.22 0.20 0.22 0.10 0.14 0.07 0.18 0.22 0.07* 0.14 0.12* 0.06 0.27 0.23 0.02« 5AF C (25) . .de by b(l br b bo b bw bu bt bs bv bn bm bl LMC.ThisHimassincludesthe Hiouttoanaverageradius TheGalaxy.Thisvalueof9îl/Tgreferstoacylinderperpen- TheGalaxy.VandeHulst,Raimond,andvanWoerden(1957). P TheGalaxy.Brandt(1960b). 6946.BecauseofthelowGalacticlatitude,someconfusion * 3034.ThisvelocityisMayall’s averagevalue;itdoesnot SMC.DeVaucouleurs(1962). 224.OE#iestimatefromHeidmann(1961);itincludesaself- 224.Brandt(1960a). TheGalaxy.outerlimit(15kpc)oftheHiradialdistri- SMC.This9E#ivalue(Kerr, Hindman, andRobinson1954) IC1613,5457,and6822.Continuumfluxupperlimitsfrom 4631 and4656.TothebeamofHarvardantenna,these 55and6946.Theerrorestimatesincludeallowancesforpossible P ch ch <0.28 <0.28 include thesingleMt.Wilsonobservation. positively identifiedasacontinuumsource.However,Heeschen with theGalacticbackgroundexistsandthisgalaxycannotbe includes theHiouttoanaverage radiusof5?7(Kerrandde continuum source. of 7?3(KerranddeVaucouleurs 1956). Vaucouleurs 1956). and vanWoerden1957). dicular totheGalacticplaneinvicinityofsun(Oort in thevelocitydomain.Thesignalseparationprocedureis absorption correctionfactorof1.13(vandeHulst,Raimond,, bution givenbyvandeHulst,Raimond,andWoerden Cooper etal.(1960). described inAppendixA4. two galaxiesappeartooverlap;theHisignalsalsooverlap confusion fromGalacticHi. have beenmade.(PettitalsoobtainedaC.I.of+0.96with 1960) andperhapsshouldbeincreasedbyafactorof^2 system. NocorrectionsforinternalandGalacticreddening (1961), usingahigherresolutionantenna,liststhisgalaxyasa. ek cl (1957) hasbeenusedastheradiusofgalacticplane. (Belton andBrandt1962). 1'. 19aperture.) ek ck ck (1961a) wereusedtoconvertthisvaluetheHolmberg (26) (27) 0.23 0.06 0.49 0.04 0.05 0.05 0.58 0.05 0.14 0.10 0.05 0.15 0.09 0.34 0.35 0.14 O.U 0.06 0.04 0.20 0.09 0.13 bu 1 1.13 1[cw 1 1 1 1 1 1 1 1 1.26 1 1 1 1 1 1 1 1 1 1.32 1 1 1 1 bv ad ^ 0.6 CW ad b ad ci ca ad ad bu br ad ca 10.3 0.2 4.6 3.1 0.14 0.98 0.28 0.62y 4.1 0.056 0.72 2.2 0.84 2.0 2.0 9.0 5.4 1.5 4.9 3.8 2.4 1.3 1.4 1.9 1.8 1.7 1.5 —>2.9 1.5 (lO^o) (28) c2 JIZ//i/9TC units)g/cm) ^ 0.20 CW (29) (30) 0.01 0.12 0.10 0.30 0.10 0.28 0.07 0.012 0.21 0.2 0.10 0.012 0.19 0.14 0.07 0.04 0.04 0.12 0.04 0.04 0.11 0.04 0.12 0.14 0.09 0.22 0.013 0.06 2flTfiri/Lpg Gm -3 ^1.2 (solar (IO* 0.2 0.18 0.24 0.39 0.10 0.48 0.23 0.86 0.08 0.61 0.58 2.4 0.74 0.17 0.08 0.2 2 0.56 0.32 7 de 1 1.1 1.5 1.5 1.5 1.0 1.1 eQ! (31) 0.8 0.83 0.70‘ 0.50 0.92 0.41» 4.8 4.8 ¿J.CW 3.4 2.1 0.5 3.0 6.8 2.6 2.9 3.2 1.9 2.5 2.3 1.2 1.6 1.8 1.6 1.2 1.7 1.1 1.6 503 1964AJ 69. . 4 90E cb ca cd ch <3f cc 06 c ci7n0 cm cl ck cj 00 cr cn 1 b e 6946.TheGalacticextinctionandreddeningcorrectionsare 3031and5194/5.Negligibleopticaldepthwasassumedin 4214.Therotationcurve,ofverylowaccuracy,suggestsan 504 SMCandLMC.Opticaldepthupperlimitscomputedfrom 4631.G.andA.deVaucouleurs(1963)suggestthatFpticai= 6822.Totalmassestimatebasedonanassumedinclination 3034.Theanomalouslyredcolorofthisirregulargalaxyhas p 224,IC1613,and598.TocorrectforGalacticreddening,we IC1613.Thisvalueof(5.5±1.1)X109TCoisig°d LMCand4631.G.A.deVaucouleurs(1963). 6822.OpticaldepthestimatebasedonassumedHidimensions IC1613,598,342,and5457.Opticaldepthestimatesbased 598,IC342,and5457.TotalmassesfromMrs.Dieter 5194/5.9Tl/ZpgvalueforScgalaxiesfromRoberts(1963).We ^ 628and5457.BecauseHolmberg’s(1958)(b/a)valuesequal 4826(M64) 4258 IC10.Thisestimate(deVaucouleurs1961c)ofthetotal a 5194/5.Avalueof14'waschosenforthemajoraxisthis 4736 (M94) 4725 4565 Coma Cluster® 0 4486(M87) 4382 (M85) 2903 Fornax 5128 5055 (M63) 4594(M104) 1023 Notes forTableIV appearonpage505etseq. 1097 221(M32) 253 185 147 7 45 3031. Munch(1959). within NGC3034. deriving theseHimasses(VoldersandHogbom1961 east-west Hiextentof«15'. angle of45°(VoldersandHogbom1961). Heidmann 1961). been explained(Mayall1960)asduetoselectiveextinction uncertain becauseofthelowGalacticlatitude. agreement with(5.9±0.6)Xl02(Tlo,thevalueobtainedby the Tbupperlimitof30°K(Kerr,Hindman,andRobinson E(B-V)~E(C). leurs (1961a)indicatesthatforsmallcolordifferentials from Holmberg's(1958)colorCbecauseEq.(30)ofdeVaucou- assume that¿11(5195)isnegligiblerelativeto2(11(5194). of 28'X25'(seeNoteba). Miss VoldersandHogbom(1961). 5236. Sandage(1961). Eq. (6)wasusedtocomputetheinternalselectiveextinctions. Holmberg’s Eq.(5)with^>=0.20andi=35°(628)ori—Tl° unity, aninconsistencywiththenonzerovaluesofinclina- have simplysubtractedtheE(B—V)valueofSandage(1962) on theHisizes(seeappropriatenoteslistedinColumn12). obscuration ofthevisibleportionisbasedonassumption equal thesumofareasindividualgalaxies. +630 km/sec. the inclinationangleasdefinedbyHolmberg);thenHolmberg’s tion angle,wecomputed“equivalent”(b/a)valuesfrom double galaxysystemsothattheareaofwould 1954) andanassumedTsof125°K. (1962a,b,d), butreducedtothedistancesadoptedhere. (5457) (notethatourinclinationangleisthecomplementof © American Astronomical Society • Provided by theNASA Astrophysics Data System NGC (1) d d d d Type E Ep Ep Sc Ep Sc Ep Sb+ E Sb+ SO Sb- Sb- Sa Sb+ SO Sb+ Sc- SBb (2) Table IV.DataforgalaxiesfromwhichH1emissionhasnotbeendetected. 309.49 315.74 230.74 237.31 295.93 283.78 267.63 208.69 226.91 298.43 138.31 145.00 106.04 123.31 121.16 120.77 119.81 11 97.33 55.88 (3) l +19.43 +74.30 +84.42 +76.02 +68.84 +88.35 +86.45 +51.15 +74.49 +44.53 +79.23 -19.08 -65.72 -80.64 -64.66 -87.97 -21.97 -14.48 -14.25 EUGENE E.EPSTEIN 11 b (4) (5) al ba k ba ay ba ay ah f av f 34.1 28.5 28.6 27.8 : 27.6 30.2 24.2 30.7 30.4 30.7 21.& 29.8 26.9 24.2 24.2 26.9 29.2 30.4 21.3 30.7»y cu ct 08 cw cv cz dc db da cy cx 224.Thisvalueistheintegratedcontinuumflux(Leibacher 4656.BecausetheHubbleAtlas(Sandage1961)photograph IC10.Computedfromw=10::,deVaucouleurs’(1961c) IC10.Weassumethatfor10,2dljyi/9flt=0.2(theaverage IC1613.Computedfromtheopticalrightascensionand IC342.ProvisionalestimatesmadebydeVaucouleurs(Dieter IC342.Thevalueof?álni/L(adistance-independent 598.MayallandAller(1942). IC342.ShapleyandSeyfert(1935). 598,IC342,and5457.Mrs.Dieter(1962e).Broadeningbythe 598,IC342,and5457.ValuescomputedbyMrs.Dieter 0 pg hI1r 2 -3 32 -26 2621 have assumedthatthegalaxyisseen“edgeon.”Using The centroidoftheHidistribution,«1950=0102î4±03and suggests rotation,wehaveusedEq.(3)toestimate2fTland estimate oftheunobscuredmagnitudeentiregalaxy. ôi95o=+01 °50'±02'(VoldersandHogbom1961),isingood estimate. that is,(£—F)o«+0.4. that theunobscuredcolorofIC10isatypicalIrgalaxy, motions arepresent.Then$=1.0Mpc(TableII,Roberts agreement withtheopticalposition. virial theoremrelation,Eq.(6),wouldhavedoubledthe2(11 STCtf i/LpgforScgalaxies(seeTableVI).Thisfactsuggests g/cm, theaveragevalueforother12Irgalaxies.The image maybeobscured,weassumedthattheunobscured galactic latitudeandredcolorsuggestthatpartoftheoptical value forIrgalaxies—seeTableVI)andthatonlyrandom declination withtheaidofLundtables(Torgard1961). adjusted areais6timesthegivenbyColumn12 adjusted theopticaldimensionsuntilan1equaled4X10 optical dimensionsaregreaterthanthoseinColumn12.We dimensions; ifthisadjustedareaisthe^correctarea,thenour than thenextlargestvalueforanIrgalaxy.Sincelow 5457, respectively;inthecaseof598,thisfluxisapproximately optical depthestimatesyieldf<3ClandC—l. 1964). correction of10km/secforrandommotionshasbeenincluded. 80 kc/secbandwidthhasbeentakenintoaccount,anda the observedvalue. too low,orboth.ThevalueoftheH1arealdensity ATOMIC HYDROGEN IN GALAXIES 509 reduced to i= 0°. The absolute photographic magnitude Table V. Numbers of observed and detected galaxies. KO of the sun was taken to be +5.37 (Stebbins and Kron 1957). Number from which Column 12. The major and minor optical dimensions, Number continuum in minutes of arc, from Holmberg (1958). The notes from which emission in to the column contain the H i dimensions, when Number H i line the vicinity observed emission of 21 cm available. Galaxy for H i line has been has been Column 13. The color Co', for spirals only, of the type emission detected detected “main body” (Holmberg 1958) of the galaxy. It is on E 6 0 2 the Holmberg system and is reduced to both i=0° and SO 2 0 0 Sa 1 0 0 outside the Galaxy. Sb 10 3 3 Column 14. The color Co'. This value is for the entire Sc 16 13* 7 nebula, on the Holmberg (1958) system, reduced to Ir 13 13 1 outside the Galaxy, and, for spirals only, also reduced Totals 48 29* 13 to i=0°. a These numbers should be increased by one because of the recent de- Column 15. The optical velocity, Fopticai- The tection of NGC 253 (Table IV, Note ac). quantity Fopticai is equal to the optical cA\/X and is expressed as the radial velocity with respect to the sun ; to the sun Fui and its estimated error (derivation the estimated error (Humason, Mayall, and Sandage described in Appendix A5). If one assumes that the H i 1956) is also included. For those galaxies where velocities in a galaxy is symmetrically distributed about the for the nucleus have been given by both Humason and center of mass of the galaxy, then Vhi equals the Mayall, the arithmetic average is tabulated (the systemic velocity of the entire galaxy. systematic difference of 28 km/sec between the values Column 17. The difference VhFopticai- of Humason and those of Mayall is not taken into account). Column 18. The velocity interval AF§, the full width Column 16. The Hi systemic velocity with respect of the line profile at one-half of the peak intensity, and its estimated uncertainty, both determined from Fig. 1. We based the uncertainty estimate on the amount the dotted line could be shifted and still be a reasonable fit to the data. Column 19, The quantity Fw, one-half of the approxi- mate total velocity width of the line profile at zero H i signal level as estimated from the extrapolated profile wings. This quantity is equivalent to the average maximum radial velocity (with respect to the systemic radial velocity) of the 171 in the galaxy. Allowance has been made for bandwidth broadening and, for spirals only, a 10 km/sec correction has been made for random motions. Column 20. The estimate of the total mass Sfll. This quantity is computed from Eq. (3), or, for NGC 4214, NGC 4449, IC 1613, IC 2574, Holmberg II, and Sextans A, from Eq. (6). Two significant figures have been retained in the values to avoid compounding roundoff errors in subsequent computations. Column 21. The total mass-to-photographic lumi- nosity ratio 9ill/Zpg. Column 22. The continuum flux, 5c, of the galaxies observed at Harvard, determined from observations made at a frequency several megacycles removed from the H i line frequency. Column 23. The total H i line flux, fSvdV. We converted the values for the galaxies observed at Leiden from J'ATßdV, where ATB is the brightness temperature, by noting that AZ^Vir ^4) = 31.2°K for Fig. 3. The H i mass STfei plotted as a function of morphological the Leiden antenna (Westerhout 1961) and that type. The type classification is that of Holmberg (1958) or Hubble 25 2 -1 (Humason, Mayall, and Sandage 1956). The derived value of 5(Vir A) = 21.3X10“ W m~ cps (Roberts 1962a). Sntffi depends on the square of the distance estimate. Column 24. The average H i line profile flux Sv © American Astronomical Society • Provided by the NASA Astrophysics Data System 1964AJ 69. . 4 90E 2 -26-2-1 Sift#!. Iff>0.4,Chasbeencomputedfromfwiththe factor C.ThisisusedwithEq.(1)toobtain 510 is computedfromone-halfof thelargeropticaldimen- plane ofthegalaxy.Itisequalto917#i/7r7£,whereR in fSydV. aid ofEq.(2);iff<0.4,wesetC=1(Sec.IIIA). is forthegalaxiesobservedatHarvardthatwere information representsamore reliableandhomogeneous optical dimensionsinsteadof theobservedorassumed optical dimensionforirregulars; wehaveusedthe sion forspiralsandellipticals andfromtheaverage H ifluxaSf,asdescribedbyEpstein(1964). error infSydVwhichexiststhereisanundetected ratio, 9T7#i/Tg(solarunits).Thisquantityisin- errors in917#iareproportionallythesameas correction factorsadoptedhere.Theobservational depth f._Wecomputedthisvaluefromtheaverage undetected inthecontinuumandisameasureof one projectstheentireHimassontofundamental dependent ofsthedistanceestimate. other workershavebeenadjustedtothedistancesand The totalprofileextentattheamplitudeofScisAFc. continuum signalScequalto0.6X10Wmcps (Epstein 1964)Hidimensions becausetheoptical (approximately equaltotheaverageScupperlimit). P y 6 d b a IC10omittedbecauseoftheuncertaintiesindistance,luminosity,andapparentsizeestimates. TheGalaxyomittedbecauseoftheunknownluminosity. NGC5194/5omitted. IC342omittedbecauseofthelargeuncertaintiesinluminosity. Column 31.ThemeanHiarealdensityahi,when Column 29.TheHimass-to-totalmassratio917#i/917. Column 28.TheHimass,2flT#i.valuesgivenby Column 27.Theadoptedvalueofthecorrection Column 30.TheHimass-to-photographicluminosity Column 26.Theestimatedweightedaverageoptical Column 25.TheratioofScAFctofSydV.This -32 32 © American Astronomical Society • Provided by theNASA Astrophysics Data System Average 9ÏI#i(solarmasses) Average 9H/Tp Range of911(solarmasses) Average 911#i/L Number ofgalaxies Number ofgalaxies Range of9H#i/Tp Range of9TC.iri/91Z Average 9ÍI(solarmasses) Range of911#i(solarmasses) Average ahi(10g/cm) Range of 512 EUGENE E. EPSTEIN worth testing for. The table also gives a qualitative KO estimate of the degree of correlation shown in each test performed; the paucity of data did not warrant the actual computation of correlation coefficients. We discuss below some of the more interesting tests. Figure 6 displays a plot of the #imass Wlm against the color Co' of the entire nebula (Holmberg 1958). (Using Holmberg’s “main body” colors instead does not significantly alter this or the subsequent figures.) The colors of the Ir galaxies have not been corrected (as the colors of the spirals were) for reddening as a function of inclination angle. However, if reddening Fig. 6. Plot of i? i due to inclination exists in irregulars, it is probably mass SHThi against small because their blue colors indicate relatively little color Co'. dust. The anomalously red irregular in Fig. 6 is the unusual galaxy NGC 3034 (Co'=+0.72). There is a suggestion in Fig. 6 that the Sc and Ir galaxies follow separate trends, with the largest values of WZffi on each trend line occurring in the bluest galaxies. We treat this suggestion with considerable caution because of the uncertainties in the 9iït^i values resulting from the (distance)2 dependence and because of the paucity of detected red galaxies in this sample. Figure 7 compares two distance-independent quanti- from which continuum emission in the vicinity of 21 cm has been detected. Table VI summarizes the ranges and average values of the pertinent parameters of the galaxies from which H i emission has been positively detected. The quanti- ties 9TCtfi/Lpg and SHIhi are independent of the distance estimates. The sequences of the values of Sfîl# i, 9iït, and i/STC within each morphological type are presented in Figs. 3, 4, and 5, respectively. The three Sb galaxies represented in Figs. 4 and 5 are NGC 224 (M31), NGC 3031 (M81), and the Galaxy. These systems are considered to have unusually large masses. Table VII summarizes the ranges and average values of the pertinent parameters of the galaxies from which H i emission has not been detected. Many of the upper limits are not meaningful because of the great distances of the galaxies concerned. (Upper limits determined with other telescopes will vary directly with system noise temperature and inversely with antenna aperture.) B. Correlation Tests of the H i Data Because of the large number of parameters involved 0m.l 0m .2 0m .3 0m .4 0m .5 Om .6 Om.7 0n'.8 in this study, we anticipated many possible correlations COLOR C'0 between the various parameters. Some correlations Fig. 7. Plot of two distance-independent quantities: the color would be due to intrinsic physical relationships and Co' and the mean Hi areal density-3 œbi. (For2 comparison, the others would be due to systematic observational effects. B i areal density near the sun is ^lO g/cm .) The color of NGC 5236 (Sc), which lies well away from the sequence formed by the Table VIII itemizes the correlations between H i data, other galaxies, is uncertain for che reason given in Note bf„ morphological type, and so forth, which we thought Table III. © American Astronomical Society • Provided by the NASA Astrophysics Data System •o g American Astronomical Society •Provided bythe NASA Astrophysics Data System b c 2 d e f f R. circular velocity,occurs,andGisthegravitational from opticalstudies(andHiinthecaseof the Holmbergopticalsemimajoraxis.TableIIlists by Holmberg(1958)forwhichvaluesofRareavailable the valuesofR/R^forthosespiralgalaxiesobserved NGC 224).TheaveragevalueofR/Ruis—0.3. for bandwidthsmearingand,spiralsonly, rotation. Equation(3)wasthensolvedbysetting estimates. Weemphasizethatthemassesobtainedin overestimation resultingfromthepresenceofun- random motions;noallowancewasmadeforpossible extent ofthelineprofile.(CorrectionstoVweremade study whoseopticalappearancessuggestsystematic estimated bydeVaucouleurs (1961b)andG.A.de here, 3X10and5Xl02n7o,respectively,agreewell from theextrapolatedwingsofprofiles(exceptfor detected continuumradiation.) estimates ofthesamegalaxy, wehaveconsideredthe to thedistanceadoptedhere inthecaseofNGC4631). Vaucouleurs (1963)bydifferent methods(andcorrected with 4X10and2.8Xl03ííí ©,respectively,thevalues the valuesdeterminedforNGC55,300,and3109from expression, (2)settingR—\R^and(3)determining certainties involvedin(1)applyingtheLohmann p the rotationcurves).Inviewoftheseuncertainties, this mannerareonlyestimatesbecauseoftheun- the totalmassesofNGC55and4631estimated P Vc= csa,whereFisone-halfofthe_totalvelocity p p0 p0 Fmc, whichentersthemassestimateassquare, m p m We haveadoptedtheLohmann(1954)methodof The quantityRmaybeexpressedintermsofRho, We assumedR=!Rhoforthosegalaxiesinour Table HI,Column20,liststheresultingmass To makeanothercomparison ofdifferentmass p p 2 Wl=%RVc/G (3) pm 507 1964AJ 69. . 4 90E , 2 2 3 that 2T+$>=0;wemaythenwriteanexpressionof pression : p=po exp(—r/2a),wherepoisthecentraldensity,r STCüieter isthetotalmassestimatedbyMrs.Dieter is included.Incontrast,9fl7/2fTCBrandt~0.5forNGC224, The resultingmassestimates aretabulatedinTable For astationaryensemble,thevirialtheoremstates intensity (TableHI,Column18). constant equalto0.425AF^,thequantityAF*being between vandv-\-dv,Sillisthetotalmass,&a where dfflZisthemasswithline-of-sightvelocities 0.50R andthemassestimateswouldbeonlyabout masses oftheirregulargalaxiesNGC4214,4449, where ^EßrandtisthetotalmassestimatedbyBrandt the form the fullwidthoflineprofileatone-halfpeak 0=0.41R. (Ifwehadchosenpoe~=O.14p,awouldequal is thecentraldistance,andaconstant. in thisanalysisforrotatinggalaxies. estimates andtheothermassconsidered respectively. Theaveragereducesto~1.2ifNGC5005 value of9í1I/9TCbbpforNGC157,2903,and5055,is ably well-definedrotationcurvemaxima.Theaverage galaxies NGC157,224,598,2903,5005,and5055 radius wherep=poe~=0.05;thisdefinitionleadsto assume thatthesegalaxiesarestationaryensembles IC 1613,2574,HolmbergII,andSextansA.We systematic differencesexistbetweentheEq.(3) of magnitudeestimatesbecause theirregularappear- HI, Column20;atbest,they areprobablyonlyorder given by Eq. (3)andbyBurbidge,Prendergast, 508 and 25% greater.) H ilineprofile. Miss VoldersandHogbom(1961)toestimatethe the velocitydistributionofallparticlesingalaxy. wherein : 0 (1962a). Thesecomparisonsindicatethatnoconsistent « 2.0;2fTland9Ebbparethetotalmassesestimatedwith (1960a), andSTC/SfTCDieter^1-0forNGC598,where (references citedinTableII),allofwhichhavereason- The potentialenergy$andthekineticTare We useavirialtheoremproceduresimilartothatof (3) Sphericalsymmetryexists. (6) Thevelocitydistributionisgivenbytheex- (5) TheaverageHolmbergopticalradiusRisthe (4) Thedistributionofthetotaldensitypisgivenby (1) Randommotionsdeterminethewidthof (2) Theshapeofthelineprofileisrepresentative © American Astronomical Society • Provided by theNASA Astrophysics Data System 2 2 9fll= 6Tr^(ab/G)=(const)£R(AFi) /G]. (6) (2 d3K—[pXi/b{2Tr)^\ exp(—^/2¿>)^, 2 4>=-G2ííl/27r^ (4) 2 T=%bm,. (5) EUGENE E.EPSTEIN Ea 1 m I1 and —l33forSb’sthe Sa. minor tomajoraxes<0.35, themaximumA^4values computed fromtheexpressionAw=—0.25esc¡bor to outsidetheGalaxy,and, forspiralsonly,also estimated byHolmbergwere used:—l03forSc’s inclination effectsbyreducingthephotographicmagni- accounts forextinctionintheGalaxy,andiseither magnitude wg(Holmberg1958). perpendicular tothelineofsight. galaxies. Forgalaxieswith i>73°, orwithratiosof angle betweentheplaneofgalaxyand not listedinTable14,wecomputedthecorrectionfrom spirals only;itaccountsforinternalextinctiondueto taken fromthereferencecited. have beenused,theyarespecificallynotedinthetables. in thecolumndescriptionsbelow;whenotherreferences for theobjectsfromwhichHiemissionhasnotbeen positively detected;TableIVliststhesameinformation galaxies :6E’s,2SO’s,1Sa,9Sb’s,SBb,16Sc’s,and Holmberg’s Eq.(7):A^4=—«(seci—1),wherea However, forNGC224,628,3031,5457,andgalaxies between Columns4and5ofHolmberg’sTable14. data fortheobjectsfromwhichHiemissionhasbeen presently available21-cmlinestudiesofgalaxies tude toi=0°.Thecorrectionisequalthedifference defined here,intheconventionalmanner,asacute ing distance. for previouslyobservedgalaxies. right ascensionandcontainsthefollowingitems: detected. Themostfrequentlyusedreferencesaregiven taken fromthedataofDanver(1942);angleis of jETiintheGalaxy.]TableHIlistsopticaland21-cm Messier number,andthereferencesforHidata Shklovsky (1960)havegivensummariesofthestudies distribution isalsoincorrect. resolved irregularssuggeststhattheassumedvelocity ances ofthegalaxiesindicatethatassumptions are incorrect.Inaddition,thelimitedinformationfor spherical symmetryandGaussiandensitydistribution 13 Ir’s.[Oort,Kerr,andWesterhout(1958) pg = +0ï28forScgalaxiesand+0^43SaSb P (including theGalaxy).Includedaredatafor48 (corrected forgalacticextinction)ands,thecorrespond- (de Vaucouleurs1961c). 11 Column 11.Thephotographic luminosityZreduced Column 10.Thecorrection,A^4.Thiscorrectionisfor Column 9.Acorrectiontowg,Aw.This Column 8.Theintegratedphotographicapparent Columns 5and6.Thedistancemodulus(m—M)o Column 1.TheNGCorICnumbername,the Table HIliststhegalaxiesinorderofincreasing Column 7.Theinclinationanglei.valuesare Columns 3and4.TheZ,bgalacticcoordinates Column 2.Themorphologicaltype(Holmberg1958). Tables HIandIVsummarizetheresultsofall pg Ppg C. SummaryoftheHiData o