195 9ApJS. . . .4. .257S in thecatalogue.Anattemptwasmadetoexcludereflectionnebulaeonbasisofa respect toionizedhydrogenisdetermined. with themarelisted.TheapparentdistributionofHnregionsisdiscussed,andthegalacticpole vious catalogues,adiscussionoftheapparentdistributionHnregions,anddeter- requires judgmentastowhetherseveralisolatedpatchesofnebulositybelongthe in termsofthehotstarswhichareresponsibleforionization.Itwasaccordance comparison oftheredandbluephotographs. detached portions.Thosefewcasesinwhichanambiguitystillexistsarenotedassuch tion isusuallysufficienttodeterminethis.Thedistributionoffieldstarscanoftenreveal same Hnregion.Knowledgeofthepositionshotstarsresponsibleforioniza- with thisprinciplethatthepresentcataloguewasassembled.Thismethodofcataloguing nebula.” AnHuregionisanentitydefinednotonlyintermsoftheionizedgasbutalso as asourceofdiametersandbriefdescriptionsHnregions. declination —27°.Theseresults,incorporatingthoseofPaperI,arepresentedhere.This mination ofthegalacticpolewithrespecttoionizedhydrogen. the existenceofforegrounddarklaneswhichdivideanHiiregionintoseveralapparently catalogue isdesignedtoserveasafindinglistforradioandopticalastronomerswell of thegalacticcircle.Thatsurveywasbasedonaseries48-inchSchmidtplates.As between galacticlongitudes315°and105°extendingseveraldegreesoneitherside cent. more nearlycoincidingwiththecenteroflight. tinued onthebasisofSkyAtlasprints,anditnowcoversentireskynorth however, containslargevariationsinbrightness, anattemptwasmadetogiveaposition mation: the NationalGeographic-PalomarSkyAtlasbecameavailable,cataloguewascon- these objects,thediametersgivenheremayhave anuncertaintyoftheorder20per to anearbyBDstar,generallyrefersthegeometric centerofthenebula..Ifnebula, table. In anearlierpaper(PaperI,Sharpless1953)acataloguewasgivenofHhregions Column 6.—Maximumangulardiameter.Owing tothediffusenatureofmany The catalogueisgiveninTable1,thecolumnsofwhichcontainfollowinginfor- The term“Hnregion”(Strömgren1948)isusedhereinsteadofthe“emission A catalogueisgivenof313Hregionsnorthdeclination—27°.Knownearly-typestarsassociated Column 7.—Classificationastoform(1=circular, 2=elliptical,3irregular). Columns 4,5.—Equatorialco-ordinatesfor1900. Theposition,measuredwithrespect Columns 2,3.—Galacticco-ordinatesbasedon the Lundpole. Column 1.—Arunningnumber.Anasteriskhereindicatesaremarkattheendof The followingsectionscontainadescriptionofthecatalogue,comparisonwithpre- © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem A CATALOGUEOFHnREGIONS Received September10,1959 Stewart Sharpless U.S. NavalObservatory II. THECATALOGUE I. INTRODUCTION ABSTRACT 257 195 9ApJS. . . .4. .257S 50 49* 42 41 39* 48 47 44 29* 46 43 40 38 37 36 31 28 27* 25* 45* 35 32 22 34 26 24 23 21 20 30* 33 18 16 14 19 17 15 11 13 12* 10 No. 9* 7* 8 5 4 2 3 6 1* © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 344.6 344.5 342.8 342.9 339.4 3418 335.0 328.3 344.4 340.4 336.3 32a4 342.9 340.4 340.2 339.2 336.2 335.1 3412 3410 339.6 334.8 334.7 334.1 333.8 327.8 334.1 332.1 327.8 327.6 333.0 319.2 338.6 315.3 334.2 332.2 328.0 326.2 324.8 317.8 317.4 316.8 323.7 3211 316.1 316.1 320.3 315.2 323.5 319.0 - 2.2 * b - 0.7 - 0.3 - 13 - 18 + 18 - 16 +34.9 - 3.9 - 19 - 2.2 - 1.1 - 3.8 - 0.7 - 3.7 - 19 - 16 - 2.5 - 3.2 +34.9 - 3.1 - 18 - 2.0 +22,1 - 12 - 2.5 - 1.2 - 3.0 +29,4 - 19 - 12 - 15 + 0.7 - 0.0 - 15 - 0.7 +2a2 - 2.2 - 2.0 - 3.5 + 0.6 +15.7 +210 +19,0 - 0.9 - 0.4 - 2.0 + 0.7 - 2.5 - 10 18 00,5 18 15.0 18 10,7 18 110 18 10,6 18 04.5 18 16.7 18 10.0 A CATALOGUEOFHllREGIONS 18 13.0 18 06.2 18 10.9 18 019 18 19.8 16 00.4 18 09.9 18 00.4 18 05.2 17 57.5 18 04.4 17 519 17 59.3 16 05.7 18 118 15 54.7 18 04.8 17 56.6 16 31.7 16 08.0 17 48,9 17 19.9 17 419 17 23.9 17 24.0 17 114 17 414 17 29.4 16 15.1 17 119 16 57.3 17 45.3 17 43.0 17 39.8 17 41.5 17 44.1 17 14.7 15 54.4 17 013 17 13,2 17 06.9 15 52.8 h m R. A. TABLE 1 -18 17 -15 39 -14 10 -16 50 -23 19 -17 46 + 040 -21 40 - 649 -14 00 -14 38 -16 46 -18 41 -20 17 -23 40 -23 49 -23 35 -24 24 -31 14 -33 59 -14 46 -16 13 -17 26 -18 16 -19 42 - 120 -30 11 -31 29 -23 01 -24 01 -10 22 -25 01 -28 49 -32 32 -35 56 -28 38 -29 05 -29 13 -29 16 -34 07 -37 00 -39 14 -25 50 - 807 -28 52 -25 21 -38 23 -22 40 -38 21 -38 00 Dec. 258 Diom 480 240 120 120 150 eter 100 35 90 40 25 35 20 40 20 60 20 20 20 90 15 45 90 30 50 25 90 80 60 15 60 40 60 10 90 10 12 30 60 12 8 8 3 3 3 5 5 4 5 2 4 Form Struc- ture Bright- ness Stars 14 10 6 2 1 1 1 1 195 9ApJS. . . .4. .257S 100 82 71* 89 88 87 85 84 80* 78 77 70 69 55 99 98 97 96 94 92 86* 83 81 72 67 53* 52* 95 93 91* 79 75 73 68 62 57 51 76 66 61 60 58 56 74 64* 59 54* 90 65* 63 No. © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 356.8 354.5 356.7 353.0 35(X8 350.6 344.7 359.6 35a4 345.1 35a2 35£2 349.7 34a 0 346.4 358.3 355.1 354.1 345.9 33.6 32.5 31.8 33.7 31.9 309 23.6 2X3 38,0 37.8 34.6 31.7 35.8 29.2 27.1 25.0 2Z8 30.7 28.6 17.9 14.5 ns 16J a4 3.8 8.1 7.9 7.6 4.1 5.0 2.7 I - 1.3 + 5.7 + 0.6 - 0,8 - 08 ~ L8 - 6.7 + 0.0 - 01 + 6.1 - L5 + 01 - 2.6 -23.7 + 0.6 + 08 - 0,4 + 3.4 - L2 - L3 + 7.9 - 5.0 + 2.0 + 2.5 - 2,7 +43.1 - 3.1 - LI + 2.1 - L8 + 0.5 - 06 - L0 - L2 - L8 -13.5 + 1.1 + 4.8 F 2.1 - 09 + L2 -109 - 2.8 -2Z4 ■F 03 - L4 + 9.9 - 0.0 - 2.1 - 2.2 A CATALOGUEOFHllREGIONS 19 57.0 19 58.0 19 52.1 19 44.6 18 12.3 19 54.8 19 24.9 18 26.6 19 4L8 19 5L0 19 45.9 19 42,2 19 38.9 18 59.2 19 25.9 18 54.4 18 25.1 18 19.6 19 24.0 19 50.9 19 3L6 19 45.1 19 4L8 16 06.8 18 58,8 18 09.8 18 39.3 18 20,1 18 40,3 18 26.4 18 25.6 18 35.0 19 07.0 19 18.7 18 58.6 19 43.2 18 44.2 18 4L7 19 52,1 18 3L3 18 26.0 19 42.6 18 5L6 19 03.9 18 57.0 18 22.3 18 27.6 18 3L6 19 20.2 19 56.5 h m R. A. TABLE 1(Continued) -11 50 -16 39 - 741 - 832 - 841 -11 46 -13 17 - 947 -23 20 + 210 + 048 - 206 +33 13 +30 00 +29 23 +23 03 +11 31 + 054 + 659 +22 08 - 023 - 228 - 505 +33 14 +25 06 +24 23 +25 41 +18 09 +20 36 +18 04 +13 47 +13 59 + 527 + 201 + 702 - 159 -14 23 - 355 - 647 +31 09 +31 16 +26 57 +28 00 +26 14 + 741 - 351 +29 02 +16 42 +26 37 +32 29 Dec. 259 Diam- 140 120 eter 20 55 25 20 75 35 40 20 50 25 25 15 40 10. 25 25 15 10 10 12 15 10 10 2 2 3 8 7 5 2 8 3 5 7 4 8 7 8 5 2 9 2 6 5 1 6 4 1 S Form |ure Stars 195 9ApJS. . . .4. .257S 101 104* 103* 102 110 108* 111 107 106 124 123 112 126* 125 122 121 114 113 109* 105* 144 142* 135 130 128 127 120 116* 115 143 141 133 119 118 148 140 139 137 134* 132* 131* 117* 147 146 138 136 129* 145 150 149 No. American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 39.2 42.0 39.2 43.1 45.9 44.1 4Z5 59.0 47.6 47.2 73.1 62.2 53.2 45.2 72.3 765 75.4 73.3 71.5 63.5 62.3 sai 57.9 55.4 52.5 5L6 49.3 75.5 74.4 74.3 73.5 72.4 70.5 57.9 55.4 52.6 52.1 51.4 764 761 761 760 75.9 75.0 74.9 669 662 63.9 66.0 65.1 + 1.9 + L6 - 9.2 - 0.3 - 4.5 - 62 - 4.4 -12.9 - L4 + 3.3 - 8.9 + 2.6 + L0 - 68 - 68 - 1.6 + 3.9 - as -17.7 - LI + 7.7 + LI + 2.4 + 9.4 + 3.5 +12.4 + 2.8 + 2.2 + 1.2 - 9.5 - 0.6 - LI - LI + 65 + 5.2 + L5 + 61 + 5.7 + 0.8 - 61 + 62 + 7.7 -17.2 - 5.9 - 1.9 - LO + 3.2 +13.1 —41,6 - 15 A CATALOGUEOFHllREGIONS 20 27.7 20 064 20 46.4 19 562 20 14.0 21 17.2 21 37.5 20 19.0 20 369 20 23.7 21 33.0 21 166 20 360 20 55.2 20 3L3 21 168 20 30.5 22 15.1 20 4L2 21 29.0 21 25.5 21 14.7 20 29.1 22 25.0 21 35.9 21 09.2 21 49.7 21 38.5 22 4L0 21 54.4 21 0L9 21 065 22 18.6 22 27,9 22 52.1 22 5L4 22 45.5 22 22.3 22 462 22 43.6 22 15.9 22 3L2 22 269 21 15.0 22 oai 21 267 22 29,0 22 52.3 21 34.8 23 03.8 h m R. A. TABLE 1(Continued) +35 01 +32 02 +38 03 +30 33 +30 16 +38 17 +45 19 +37 04 +40 00 +39 56 +35 59 +36 26 +37 40 +46 32 +29 39 +39 46 +47 01 +62 52 +55 25 +44 05 +49 15 +49 29 +43 31 +43 56 +63 48 +59 22 +54 11 +49 54 +14 23 +57 59 +57 32 +61 08 +62 47 +67 50 +63 52 +55 38 +46 48 +57 11 +57 42 +58 55 +57 02 +59 33 +38 04 +57 56 +64 13 +58 00 +59 24 +57 58 +58 14 +64 36 Dec. 260 1080 Diam- 210 480 240 180 160 160 160 170 140 eter 20 40 50 50 18 70 90 15 15 80 90 40 90 40 90 13 30 30 15 10 7 3 5 9 3 2 5 2 9 1 1 2 2 4 5 1 2 4 1 1 horm ture P-__ Struc- Bright- J,ura St s ness 195 9ApJS. . . .4. .257S ' 180 152 155* 172 159 156 186 185* 184* 175 174 170 168 163 162* 160 157* 154 153 151 199* 188* 187 183 176 173 169 166 164 161 158 200 197 190* 182 177 171* 165 195 192 189 181 179 167 196 194 178 198 191 193 No. © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 102.5 105.1 104.2 103.7 104.0 103.8 104.0 103.8 103.6 105.7 105.2 7M 76.5 77.8 77.8 765 8Z3 79.3 79.0 766 85.3 83.5 82.3 79.2 82.6 81.3 79.5 863 864 83.6 817 79.5 94.4 89.4 92.6 917 910 860 87.5 87.2 860 79.9 95.9 968 864 90.5 90.3 963 88.1 99,2 + 3.3 + 63 - 66 - 14 - 64 + 2.7 + 0.3 +25.6 - 0.0 +167 - 11 - 16 - 15 + 18 + 2.8 + 16 + 3.2 + 0.4 - 5.2 + 2.2 + 4.9 + 2.5 - 67 + 63 + 61 + 3.2 - 3.7 + 67 + 0.4 + 3.2 + 2.7 + 2.8 - 15 - 5.9 + 2.2 - 0,7 + 4.8 + 0.9 4.1 Z6 Z8 61 66 10 69 16 11 11 64 63 A CATALOGUEOFHllREGIONS 23 114 23 09.4 23 018 23 117 23 010 22 568 23 35,1 23 16.3 23 112 22 54.5 23 59,5 23 49.0 23 30.8 23 267 22 52.8 22 55.1 22 34.1 23 566 22 47.5 23 23 37.4 23 33.7 23 48.1 h m 0 42,8 0 25.9 0 34,6 0 261 0 0 47,8 0 43,2 0 0 162 0 44.2 0 53.9 0 47.0 R.A. 217 468 39.4 42.4 34.4 43.4 39.5 39.7 42.6 32.6 25.8 29.2 04.6 24.2 164 166 02.5 02.5 TABLE 1(Continued) +64 08 +56 32 +60 58 +60 36 +59 43 +58 15 +60 14 +60 39 +61 19 +60 39 +58 12 +80 23 +62 05 +60 42 +61 23 +59 30 +64 40 +56 44 +64 09 +61 11 +59 49 +59 25 +64 12 +62 23 +87 15 +66 36 +64 04 +64 18 +60 25 +62 36 +60 27 +56 04 +65 10 +62 19 +61 55 +59 55 +61 31 +61 35 +61 34 +61 00 +57 51 +61 20 +61 49 +59 12 +63 42 +62 26 +59 13 +59 13 +60 00 +59 17 Dec. 261 Diom 420 180 150 120 eter 120 20 40 80 60 60 55 90 40 30 40 20 10 10 10 35 10 10 10 15 10 15 2 2 5 3 7 5 7 2 2 1 4 2 2 2 1 9 2 1 1 3 2 9 5 6 Form Struc- ture Ä" Stars 195 9ApJS. . . .4. .257S 235 14134*4.1 229* 139.7-0.9 225 135.7+4,3 223 133.44-3.7 218 127,04-12,4 214 125,4-2,8 249 1567+5.5 242 150,14-16 237 14164-16 230* 140,74-0,0 227 136,44-2.3 216 126.3+L9 215 126.1-4.6 205* 116.2-I-0.7 203 1U2-L0 248* 15674-4.3 247 15664-2,3 245 154.3-32.9 243 1518-2.7 239 146,8-ia7 238* 144,1-19,6 236* 1413-C14 233 14114-3.7 232 14114-4.6 228 136.94-0,4 221 128,44-3.8 219 127,04-3,7 217 126.84-4.4 202 108,2+2.7 201 106.1+Z4 250 157.4 -23.4 246 154.8-15.1 244* 152.3-4.4 241 14a64-5.5 240* 147.94-0.1 234* 14114-12 231 1410+3.9 226 136,24-0.3 224 133,84-5.7 220* 12a0.-Ill 213* 124,8-2.5 212 123,1-I-3.6 211 122.3+3.5 207 118,9-f3.1 206 118,3+0.0 222 133.2-7.8 210 120.4+3.9 209 119,34-0.7 208 119,0+3.0 204 113,4+3.8 No. Ib © American Astronomical Society A CATALOGUEOFHllREGIONS 5 215+3421 3 54,1+3620 4 565+1357 5 160+3316 5 32.0+3544 5 35,7+3609 5 lOll44206 4 23.6+3503 3 47,7+5708 3 10,9+5916 3 57,3+51 5 32.6+3552 5 15,9+3402 5 09,7+3421 5 20.0+4032 5 33,3+5208 4 37.6+4638 4 14.5+4408 4 29.3+5044 4 23,2+5220 3 465+5254 3 14,5+5431 5 28.5+2153 5 45,6+2659 5 34.7+2803 4 16,0+1918 5 34.3+3548 5 13.0+3851 4 166+4222 4 33.0+5011 4 03.5+5054 4 12,3+5254 4 34.8+710 5 33.3+2314 5 06,8+3720 5 04.3+3752 5 20,1+4253 4 48,7+4714 4 13,6+4441 4 12.0+5244 3 55,7+5103 h mof 6 14.9+2308 5 57,7+3015 4 25,5+1754 5 24,8+3412 4 54.3+4612 4 513+4751 2 55,34-6005 6 10.6+2232 6 02.5+2138 R. A.Dec. TABLE 1(Continued) Provided bytheNASA Astrophysics DataSystem 262 horm Diam- FormStruc- 720 32 120 32 320 32 300 32 170 32 120 32 180 13 eter ture 70 32 70 21 50 32 20 32 40 2 40 32 55 32 65 32 80 32 20 31 45 12 80 32 30 -33 14 32 10 32 50 23 65 31 10 32 10 32 12 31 10 32 12 32 4 12 5 32 7 32 2 3 3 2 5 12 7 12 3 2 5 23 6 32 13 2 2 3 8 32 6 32 2 3 9 2 4 11 112 5 32 9 11 13 2 Bri 3 3 3 3 2 2 3 2 2 3 2 2 2 2 2 2 2 3 1 3 3 2 1 2 3 3 3 2 3 3 2 2 2 3 3 2 3 2 2 2 2 3 1 1 1 1 1 3 1 1 Star, 5 8 4 4 2 2 6 1 1 1 1 1 1 1 1 195 9Ap JS 4. . 257S 298* 300 299 292* 294 296 289 291 290* 288 297* 295 293 287 286 285 280 278 271 283 282 276* 274* 284 281* 279 277 275* 273* 272 268 269 262 256 270 267 266* 265 264* 261 258 260 259 257 255 263 254 253 251 252* No. © American Astronomical Society 198.9 195.5 192.2 192.1 198.7 193.2 191.9 191.9 19L4 188.2 185.0 177.7 187.1 1864 1865 178.5 1767 181.5 185.8 179.7 1706 164.1 1764 174.4 172.9 165.5 165.5 176.1 175.0 164.5 164.2 174.6 162.4 161.8 1603 163.9 163.4 IbZS 160.3 160.2 174.0 162.8 162.4 16L2 1606 1604 157.7 1603 159.9 157.7 - 02 + 08 + 02 - 0.6 + 06 + 08 - 04 - 3,5 - 05 - 3,4 + 2.1 - U - 08 + 3.2 + 3,0 + 01 -2L5 + 01 -100 -19.0 +307 - 3.1 - 1,2 -17.6 +15.7 + 3.7 - 08 + 03 - 06 - 08 - X6 - 02 -105 -15.3 - L4 + 1.4 -15.3 -105 - 05 + 09 -25.7 —HI -21,2 + 1.5 + 3,4 + L5 + 5.1 + 1.4 + 1,3 + 2,0 o A CATALOGUEOFHUREGIONS 6 401 8 408 7 03.6 6 308 6 501 6 33.3 6 39.9 6 54.6 6 49.6 5 14.9 5 35.7 5 300 6 29.1 5 304 5 205 6 264 6 35.3 7 23.5 6 09.3 6 03.7 h m 6 09.4 6 07.0 6 07.3 6 19.8 4 27.5 4 49.8 6 05.8 6 068 6 07.7 6 06.5 R.A. 265 500 261 14.0 01.1 006 57.1 50.6 59.7 108 29.7 04.6 04.6 009 13.1 13.2 102 163 004 03.2 TABLE ](Continued) Provided bytheNASA Astrophysics DataSystem -15 12 -15 05 -13 01 -12 11 -11 19 -11 10 -11 04 - 754 + 918 - 409 -10 18 - 714 - 916 - 423 - 440 - 023 - 532 + 048 + 136 + 020 +13 21 + 818 + 5 +10 00 +12 22 +12 23 +12 50 + 720 + 952 + 602 +15 49 +13 28 +13 51 +14 18 +15 19 + 530 +17 28 +17 57 +20 05 + 539 +18 00 +17 58 +18 00 +18 04 +20 31 263 Dec. 37 52 46 30 03 00 1200 Diam- 200 390 120 250 100 eter 22 21 80 11 35 60 17 11 40 20 50 60 22 12 22 20 35 70 45 40 11 3 8 7 7 8 1 3 6 1 1 2 3 2 4 8 1 4 5 1 1 1 3 1 rorm ture Form Struc- Bright ness - Stars 10 11 1 1 1 1 1 3 1 1 4 9 9 1 1 1 1 1 1 195 9ApJS. . . .4. .257S 301 311 304 307 302 305 313 309 308 306' 303 312* 310* No. © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 210.9 202.5 2014 20013 272.5 219.2 204.9 202.3 202.3 202.0 20019 199.1 2015 - B.2 - 5.3 - a9 + GL9 -112 + 2.1 + 11 + 2.1 - 3.1 +39.6 +H0 + 14 + 10 A CATALOGUEOFHllREGIONS 12 4a2 6 39.3 7 27.2 h m 7 25.7 7 05.4 7 4a2 6 49,8 8 54.8 R.A. 27.7 sao 311 2&2 oa9 TABLE 1(Continued) -22 19 -25 18 -26 11 -24 25 -19 13 ■23 49 ■18 32 ■18 54 ■18 19 ■24 02 ■22 18 ■16 46 •18 19 264 Dec. Diam- 200 720 480 eter 90 45 35 21 30 12 12 9 4 6 SrU F°"" !urS-Ä"Star, 195 9Ap JS 4. . 257S 312. Sizeuncertain duetosouthernlimitation ofPalomarAtlas. 244. TheCrabNebula. 238. TTauriNebula. 108. -yCygniNebula. 104. MaybepartofIICygassociation. 103. TheNetworkNebulainCygnus. 310. Incompletering.Sizeuncertain duetosouthernlimitationofPalomarAtlas.Contains cluster 252. NGC2174-75.InIGemassociation. 240. Peculiarfilamentarynebula.Radiosource. 236. IC410.ContainsclusterNGC1893. 234. MaybepartofIAurassociation. 220. NGC1499.Sourceofexcitation:£Per.PartIIPerassociation. 205. PartofICamassociation. 109. TheCygnusNebula.greatsizeandgrossfilamentarystructureofthisnebulasetitapartfrom 105. NGC6888.Peculiarfilamentarystructure.MaybepartofIICygassociation. 298. Containspeculiarringstructure; similartoNo.162. 274. NGC2237-38.Crescent-shaped;similartoNo.188. 266. Maybeplanetary. 264. Sourceofexcitation:XOri. 248. IC443.Highlyfilamentary;radiosource. 230. Nos.229and234appeartobesuperposedonthisnebula. MaybepartofIAurassociation. 229. IC405. 213. Incluster. 131. IC1396.PartofICepassociation. 129. PartofICepassociation. 126. PartofILacassociation. 117. NGC7000. 116. Maybeplanetary. 297. Maybeconnectedwith No. 296. 292. IC2177.Maybeconnected withNo.296. 290. Maybeplanetary. 281. NGC1976,82.TheOrion Nebula. 276. TheBarnardLoop.Several detachedportionstoNEandSW. 275. PartofIMonassociation.ContainsclusterNGC2244. 273. NGC2264.AppearstobeconnectedwithNo.275by lanesofnebulosity. 134. IsolatedpatchesofnebulosityaroundXCep. 132. PartofIICepassociation. 157. Small,verybrightcondensationinnebula. 155. PartofIIICepassociation. 142. PartofIICepassociation.ContainsclusterNGC7380. 171. NGC7822. 162. NGC7635.Peculiarellipticalstructurenearcenter;similartoNo.298. 199. IC1848. 190. IC1805. 188. Crescent-shaped;similartoNo.274. 185. 7CassiopeiaNebula. 184. NGC281. 49. M16.PartofISerassociation.ContainsclusterNGC6611. 91. Verylong,thinfilament. 80. Maybeplanetary. 86. NGC6820.Containscluster.PartofIVulassociation. 64. Appearstobehighlyobscured. 54. PartofIISerassociation.ContainsclusterNGC6604. 53. Aboutsixdetachedportions. 45. Ml7.Twodetachedportionsapparentlyseparatedbyforegrounddarklane. 39. MaybepartofIIISgrassociation. 30. M20.PartofIISgrassociation. 25. MS.AppearstobeconnectedwithM20.PartofISgrassociation.ContainsclusterNGC6530. 65. ContainsclusterNGC6823. 52. Maybeplanetary. 29. AppearstobeconnectedwithM8. 27. Sourceofexcitation:Oph. 71. Maybeplanetary. 12. ContainsclusterNGC6383. 9. Sourceofexcitation:trSco. 7. Sourceofexcitation:ôSco. 1. Sourceofexcitation:ttSco. Like IC443,theCygnusNebulaisalsoastrongradiosourceandhashighinternalmotions(Courtes American Astronomical Society• Providedby theNASA Astrophysics DataSystem any knownHnregion.Thefilaments,especiallyintheregionillustratedbyMinkowski(1955), bear astrikingresemblancetothefilamentsofIC443exceptforgreatdifferenceinangularsize. 1955). EvidentlythisnebulacannotbeconsideredtoanormalHnregion. NGC 2362. NOTES TOTABLE1 266 STEWART SHARPLESS
Column 8.—Classification as to structure, ranging from 1 = amorphous to 3 = filamentary. Column 9.—Classification as to brightness on an arbitrary scale, from 1 = faintest to 3 = brightest. Column 10.—The number of associated stars as identified in Table 2. Stars which are associated with these regions and are responsible for their ionization are listed in Table 2. Magnitudes and spectral types are taken from the Henry Draper Catalogue or its extensions. Some stars are listed with no spectral type. Most of these were taken from the finding list of OB stars of Nassau and Morgan (1951), while a few of them are central stars in circular H n regions and are probably the exciting stars although no spectra are available. In the case of regions associated with large aggregates of early-type stars, e.g., Orion, only a partial list of associated stars is given.
III. PREVIOUS CATALOGUES Table 3 contains descriptions of previous Ha surveys. The first column gives the refer- ence to the investigation. The next four columns describe the equipment and the spectral region employed for comparison with the Ha plates. Succeeding columns give the interval of galactic longitude covered by the investigation, the number of entries contained there- in, and the symbol used here to designate each catalogue in Table 4. Each of the entries of these catalogues, in the respective region of overlap, has been accounted for in terms of the present catalogue numbers in Table 4. Most of the previous surveys were compiled on the basis of principles similar to those used here. The close agreement of these catalogues with the one given here attests the validity of the cataloguing procedure, especially in view of the large differences in aper- ture involved. Many of the H n regions listed in Table 1 were not found in the earlier surveys on account of the smaller apertures employed. In general, those regions missed by the earlier surveys are those having diameters less than 15' and low surface brightness. A few discrepancies between the present catalogue and earlier ones result from the fact that some of the previous investigations listed occasional planetary nebulae, reddened extragalactic nebulae, or clusters, since the true nature of these objects was not recogniz- able on the small-scale plates on which they were found. All such objects are properly identified in Table 4 as follows: 1 = reflection nebula; 2 = galactic cluster; 3 = plane- tary nebula; 4 = globular cluster; 5 = extragalactic nebula; 6 = not visible on Palomar Atlas. Several regions listed in Paper I are not included in Table 1. These were visible on original 48-inch Schmidt plates but were not found on the prints. These were omitted for the sake of homogeneity of the catalogue.
IV. THE APPARENT DISTRIBUTION OE H II REGIONS The apparent distribution of H n regions is shown in Figures 1 through 5. The Net- work Nebula, the Crab Nebula, and IC 443 have been included, although these are not typical H ii regions. The larger regions are represented by hatched areas, while, the smaller regions, regardless of shape, are represented by circles. The features of the apparent distribution discussed in Paper I are even better defined here. The decrease in average angular diameter from ¿ = 315° to / = 5° is in keeping with an inner spiral arm (Sagittarius arm) going off in perspective in the direction of Scutum (Morgan, Whitford, and Code 1953); and the increase in angular sizes from l = 15c to ¿ = 55° agrees qualitatively with the curvature of our own spiral arm (Wes- terhout 1957). The relative scarcity of nebulae between l = 92° and 102°, and between l = 56° and 66°, is indicative of a rather spotty distribution of H n regions in the Perseus arm. The second gap is apparent also in the distribution of OB stars (Nassau and Morgan 1951) and red supergiants (Nassau and Blanco 1954).
© American Astronomical Society • Provided by the NASA Astrophysics Data System 195 9ApJS. . . .4. .257S Nebulae 25 22 11 10 15 13 12 7 9 8 5 2 1 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 315033 315031 317846 323019 317858 317837 317828 323110 323025 319701 315034 315032 314701 317842 319703 319702 319699 323016 323015 315023 314704 314700 317844 319881 315026 315024 317861 317845 156327 147165 323117 143018 318406 161853 143275 156688 165052 164906 164865 159176 157038 164947 162978 162718 161839 158186 157504 156468 153919 164816 164794 Star A CATALOGUEOFASSOCIATEDEARLY-TYPESTARS 10.2 U8 10,0 9.4 3.08 6,30 7.14 3.00 8.0 5.71 6*73 8.3 7.9 Z54 9.0 6.13 9.0 5.86 6.81 ao 6.79 Mag. Sp. Oa BO B5 B Od Oa BO BO B2 B8p B3 B5 B Oe 5 B5 B5 0e5 B1 B5 B B3 B5 B3 0e5 B3 B3 B5 B5 B5 B5 B B B2 B5 B2 BO B5 B5 BO BO B3 B5 B5 B5 B BO B B B B3 BO TABLE 2 267 Nebulae 27 32 29 44 30 49 48 47 41 37 35 34 31 50 54 46 45 -llo4586 -15o 4914 -14o 5037 312973 314031 315035 312974 165921 166107 166056 312875 164492 149757 165516 166192 168015 312989 167379 166033 168607 167771 167412 167411 313098 167815 167263 168206 168112 168207 167543 165319 168625 168163 167336 167722 167971 167834 168504 168183 168075 167451 168894 168302 167657 167633 167478 168137 167519 167497 168726 168987 Star 10.1 10.1 10.1 10.3 7.7 7.64 7.59 2,70 6.02 9.0 a7 a9i 9.7 6.22 a9 9.7 9.4 9.4 7.34 9.4 9.7 9.2 9.1 9.4 6.37 8,87 9.2 9.2 8.3 a9 as 7.9 8.1 a6 8.7 9.4 a9 9.9 a7 a3 as Mag. Sp. BO 0e5 B5 BO B9 B5 B B5 B5 B3 Oa B2 Oe 5 B5 B1 B1 B BO B 0e5 B5 B5 B2 B3 BO BO B3 B3 B B BO B5 B B B5 BO B B B B BO B2 BO B5 B3 B5 B8 B3 195 9ApJS. . . .4. .257S Nebulae 107 112 105 125 119 101 117 131 126 132 130 129 137 155 151 140 142 134 55 69 57 85 82 86 87 84 88 92 98 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem - 8®4623 —12o 4982 -12 o4970 -llo 4665 +45o 3216 +46o 3474 +54o2726 231616 344775 338916 338936 173371 344776 214680 332737 177347 187282 331626 332755 344783 187323 227018 332757 205794 205196 202214 186943 211853 203064 192163 211564 206773 205948 199579 211880 208904 206267 197460 216532 208682 197911 217035 215605 210839 240171 215835 215806 217061 216898 216658 216711 Star A CATALOGUEOFASSOCIATEDEARLY-TYPESTARS 10,7 11.07 6.80 8.0 Mag. Sp. 6.93 6.01 7.44 9.5 9,98 4.91 5.06 8.6 7.60 5.65 9.0 5.64 8.3 8.7 7.36 7.9 6.98 9.1 8.5 8.6 5.19 7.76 5.85 9.4 8.0 9.4 9.5 ao a4 B6 B8 B0 B9 B5 Oa Oa B B B B5 B2 B B5 Oe 5 Oe 5 0b B9 B0 Oe 5 B2 Oe 5 B B5 Ob Oc B5 B2 Od BO TABLE 2(Continued) B8 BOp B B2 B B8 B3 B2 B3 B B B5 B B B 268 Nebulae 157 162 160 171 170 166 169 165 177 173 184 185 190 199 202 200 +60o 2522 +66©1661 +60© 498 +61o 2494 -1-66© 1675 +59© 2786 +60© 497 +60© 39 +63© 2093 +60© 501 +60© 2607 4*1© 105 +60© 586 +60© 512 +60© 493 +62© 524 217463 217312 217086 219460 240234 219287 219286 220057 218723 240250 219063 218323 224938 237012 237011 237007 237015 237019 237090 237121 237091 Star 15558 15570 15629 17520 20134 17505 18326 20959 20898 19820 19441 2928 5394 5005 7.7 8.9 7.70 7.8 9.2 8.6 8.5 *62 a6 Mag. 6.82 7.22 9.1 7.30 B9 7.82 7.7 2.25 8.7 7.91 ao 7.11 8.4 9.2 8.7 9.4 9.0 7.51 9.4 7,66 7.09 ao 9.0 9.3 a2 as a3 BO B2 B8 B BO Oa B B BO B5 B5 B5 BOp B2 B B B B BO Oe 5 B B B B B B5 B5 B8 B5 B8 B3 B8 B2 195 9ApJS. . . .4. .257S Nebulae 232 224 220 206 216 205 229 247 273 248 245 236 234 263 261 249 237 252 254 264 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem +42 ©1286 +50o 886 +34© 1074 242926 254577 242935 242704 255055 242908 245203 255134 254346 242855 253247 37767 29997 35653 34078 24912 47839 46883 35619 37737 24431 47777 43703 35633 45995 43582 25340 35652 47732 46783 46005 37035 36881 34989 43836 43078 41690 25558 36895 41997 42088 43818 43753 46075 37051 36894 36822 36862 Star 36861 A CATALOGUEOFASSOCIATEDEARLY-TYPESTARS 10.0 10.0 8.9 4.05 6,70 0e5 9.6 9.0 7.50 8.4 ao 5.81 7.8 7.7 7.7 9.1 9.6 Mag. Sp. 7.92 7.03 8.0 5.25 9.5 a6 7.79 7.7 8.7 9.0 5.33 7.65 5.83 a9 5.59 4.53 5.71 as 7.40 7.03 ai 9.5 ae 8.7 a4 4.68 9.2 9.6 6.46 a7 5.56 7.9 3.66 0e5 B5 B8 B3 BOp B5 B1 B0 B3 B8 B 0e5 BO 0e5 B3 B9 0e5 B1 BO B2 B3 B5 BO B0 B B3 BO B9 B2 B3 BO B2 BO B9 0e5 B2 B2 B8 B8 B8 B8 BO B2 B8 B8 B8 B9 BO TABLE 2(Continued) 269 Nebulae 275 277 289 298 297 296 292 279 281 280 310 306 295 311 302 293 282 308 47961 47887 46149 46056 46966 46223 46202 46150 48977 47129 46485 37742 46559 37018 46573 37043 37022 46573 59986 59961 53623 53755 46847 46711 Star 56925 53975 53948 53756 53456 52721 53367 47432 57060 59813 54439 54306 54025 53857 52942 48979 37041 50896 59548 59442 59934 53974 57061 60146 64568 64315 59960 10.1 7.27 7.66 7.02 7.14 7.3 5.84 aso 6.06 a3 a 16 7.96 as ai Mag. Sp. 9.7 5.36 2.05 7.20 7.01 ai 4,65 Z87 5.17 a9 a9 9.1 9.3 9.2 5.28 67 657 ai3 9.1 7.8 as 640 7.8 9.3 9.3 as 8.4 as 638 9.7 as 4,90 64 689 4,40 655 B3 B3 BO B5 B2 B2 B2 B2 B2 AO 0e5 0e5 BO B2 B2 Ob B1 B5 B3 BOp Ob B3 B2 B9 BO B B B Oe B5 B5 B5 BO B B9 B9 B9 B8 B5 BSp B3 B5 0e5 B8 B9 B8 B5 B3 B3 B5 B5 195 9ApJS. . . .4. .257S pole. Sincetheyareextendedobjects,theirdiscoveryislessinfluencedbyinterstellar some limitingmagnitude. ing intonegativelatitudes. biased byirregularobscurationthanapolebasedonvarioustypesofstarsselectedto absorption, andagalacticpolebasedonHiiregionscanthereforebeexpectedtoless an idealtypeofobjectonwhichtobaseacomputationtheco-ordinatesgalactic 270 fits theapparentdistributionofHnregions: L andBaretheco-ordinatesofnewpolein theprovisionalsystem,and90°+ÿis where Sharpless andOsterbrock(1952). Strohmeier (1950) and wherelbaretheco-ordinatesofanH iiregionrelativetoaprovisionalpole, H. M.Johnson(1955) Bok, Bester,andWade(1954)... Sharpless (1953) 336°
TABLE 4
CTi COMPARISON OF PREVIOUS CATALOGUE DESIGNATIONS CTiLO WITH THOSE OF TABLE 1
Str - S Y - S E - S E - S YM - S YM - S
1 6 13 49 52 60 111 163 35 4 94 205 2 302 14 25 53 59 112 164 36 6 95 205 3 305 15 27 54 113 165 37 45 96 206 4 6 16 12 55 69 114 166 38 45 97 207 5 i 56 66 115 168 39 46 98 211 6 6 E - S 57 65 116 169 40 6 99 212 7 298 58 76 117 170 41 53 100 216 8 294 59 75 118 3 42 54 101 217 9 296 1 2 60 78 119 6 43 4 102 219 10 296 2 3 61 74 120 172 44 56 103 i 11 301 3 6 62 80 121 173 45 58 104 226 12 296 4 10 63 79 122 175 46 59 105 228 13 296 5 4 64 83 123 6 47 60 106 233 14 296 6 5 65 86 124 177 48 64 107 232 15 296 7 8 66 88 125 6 49 65 108 235 16 297 8 11 67 87 126 179 50 66 109 237 17 296 9 14 68 92 127 180 51 68 110 240 18 292 10 13 69 90 128 181 52 69 111 241 19 296 11 12 70 89 129 182 53 71 112 242 20 i 12 17 71 93 130 185 54 4 113 244 21 273 13 16 72 95 131 6 55 3 114 247 22 273 14 18 73 97 132 186 56 82 115 248 23 273 15 20 74 98 133 187 57 86 116 252 24 273 16 19 75 101 134 188 58 88 117 254 25 273 17 15 76 105 135 189 59 90 118 255 26 273 18 21 77 104 136 190 60 92 119 257 27 280 19 22 78 108 137 191 61 93 120 256 28 273 20 26 79 109 138 195 62 95 121 261 29 275 21 28 80 116 139 197 63 97 122 263 30 252 22 30 81 112 140 194 64 101 123 267 31 261 23 25 82 115 141 192 65 103 124 269 32 2 24 34 83 109 142 193 66 104 125 264 33 276 25 46 84 109 67 105 126 272 34 276 26 38 85 109 YM - S 68 109 127 2 35 264 27 29 86 117 69 112 128 6 36 277 28 42 87 120 70 116 129 273 37 277 29 32 88 121 10 3 71 119 130 273 38 281 30 31 89 13 4 72 125 131 i 39 264 31 40 90 124 14 6 73 124 132 3 40 244 32 35 91 132 15 8 74 129 133 274 41 264 33 41 92 135 16 8 75 147 134 i 42 264 34 43 93 138 17 8 76 152 135 1 35 44 94 139 18 8 77 153 136 i 36 i 95 144 19 9 78 156 137 i 138 277 Y - S 37 39 96 142 20 11 79 157 38 i 97 146 21 11 80 158 139 278 39 37 98 143 22 11 81 162 140 280 1 296 40 47 99 154 23 11 82 164 141 276 2 276 41 54 100 147 24 12 83 165 142 2 3 275 42 49 101 148 25 13 84 168 143 289 4 264 43 45 102 149 26 15 85 169 144 i 5 236 44 48 103 155 27 16 86 170 145 292 6 229 45 53 104 152 28 18 87 5 146 295 7 220 46 50 105 153 29 17 88 173 147 298 8 199 47 57 106 156 30 19 89 175 148 301 9 190 48 56 107 158 31 29 90 6 149 302 10 131 49 58 108 159 32 31 91 188 150 305 11 117 50 55 109 157 33 37 92 i 151 307 12 54 51 61 110 162 34 43 93 1$4 152 309
271 © American Astronomical Society • Provided by the NASA Astrophysics Data System vOOO-^ioui-P»^>ir\it—iovOOO'^iCTsui4^v>)roi—•ONDCX)'^joun4^v>)r\jh-‘ov00o-«joui4^v>>roh-'0'ûoo~^losai^v>)ro(—•OvOOo»Njo^ui4^v>JhJf-j C -S 219 230 229 228 230 230 263 229 226 217 216 211 210 209 236 207 220 206 212 208 205 201 202 199 197 199 190 191 196 198 193 194 190 184 190 190 188 187 192 185 177 175 173 179 © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem 116 298 111 296 108 296 104 275 113 296 112 288 107 295 103 273 118 9 117 310 114 296 109 292 106 293 102 273 101 282 COMPARISON OFPREVIOUSCATALOGUEDESIGNATIONS 105 100 273 115 294 110 297 97 275 99 273 98 280 77 240 95 248 78 232 76 235 93 267 92 269 73 231 96 249 94 248 87 252 86 261 72 71 233 90 257 85 247 83 242 79 75 230 74 240 70 91 255 89 256 88 254 81 80 277 65 281 84 252 82 264 69 230 67 279 66 281 63 264 62 237 60 234 68 281 64 264 61 230 C -S WITH THOSEOFTABLE1 172 89 168 88 163 82 158 66 177 109 173 93 167 87 164 160 170 84 169 92 165 162 78 159 65 154 60 152 64 149 68 136 43 176 109 175 101 174 109 171 90 156 69 153 61 151 58 148 50 147 53 144 45 135 41 131 42 130 29 161 71 157 155 59 146 48 142 49 140 37 138 39 137 44 134 35 133 40 132 126 25 166 86 150 56 145 45 141 54 139 128 46 127 124 28 119 8 143 49 129 34 125 30 123 22 121 12 122 120 11 C -S TABLE 4(Continued) 272 223 117 219 109 228 103 224 103 215 109 220 109 218 109 213 109 234 117 233 109 232 103 231 103 229 117 226 109 225 109 221 103 211 109 208 109 205 109 230 117 227 103 222 103 217 109 216 109 214 109 212 112 210 109 209 116 207 109 206 109 204 109 201 109 236 117 203 109 202 109 235 200 109 192 109 190 109 197 109 194 109 191 109 187 109 185 105 199 109 198 109 195 104 193 109 188 109 186 109 184 109 180 109 179 109 196 109 189 109 183 109 181 109 178 109 182 109 C -S 285 171 284 170 282 171 280 165 279 164 277 162 274 157 265 148 251 135 283 171 281 168 275 159 272 158 268 163 254 252 132 286 171 278 163 276 157 266 155 263 143 259 126 258 126 247 273 161 271 160 270 156 269 151 264 154 262 146 260 139 257 126 256 141 253 135 250 140 248 134 246 125 245 131 267 152 261 142 249 135 244 124 242 114 240 119 239 109 238 129 237 109 243 118 241 136 255 145 C -S G -S 3 297 2 296 4 298 1 292 34400 49 34101 44 33402 {ll 32801 16 32701 18 32100 11 31500 2 34600 54 34401 48 34201 46 33201 22 32603 15 32301 12 31800 8 35201 60 34202 45 33903 37 32300 13 80 46 78 37 84 54 76 30 75 29 74 28 73 27 85 54 82 48 71 22 81 45 77b 35 77 a34 72 25 69 15 68 13 58 83 49 79 44 70 16 67 12 64 63 60 65 62 61 57 2 66 11 59 G -S 7 307 9 311 8 310 6 302 5 301 B -S 195 9ApJS. . . .4. .257S © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem + I 273 o ro O ro ro OJ O ro O O ro m o O o O o o o lo "Sb X) ro LO rtí H En # d tfl