The Caldwell Objects

More documents

Recommendations

Info

17 & 18 lower approach speeds as mere coincidence, but in a 1994 Astrophysical Journal paper, Halton C. Arp (Max Planck Institute for Astrophysics, Germany) announced that 22 major companions to Local Group galaxies — his entire sample — have recession velocities, or redshifts, that are positive with respect to their respective "parent" galaxies, as is the case with NGC 147, NGC 185, and M31. The chance that this can be an accidental configuration of velocities, Arp contends, is only 1 in 4 million, implying, to critics of the Big Bang, that galaxy redshifts have nothing to do with the universe's expansion. Until I took on this project, I had never considered looking for the "other" companions to M31. Now I'm glad I did. To my surprise NGC 147 and NGC 185 both are visible in the same 7x35 binocular field (with effort) from a dark sky. The 9th-magnitude galaxies are separated by about 1°, with NGC 147 being the more difficult to see. The clarity of the night has a profound effect on NGC 147's visibility; even the slightest drop in transparency will 76 steal the galaxy from view. Because of its slightly brighter apparent magnitude and its more concentrated light profile, NGC 185 has a greater chance of withstanding the atmospheric whims. Locating these challenging objects is simple. Look for a north-south-oriented chain of three roughly 5th-magnitude stars 6° to the north of M31. The brightest of these stars, Omicron (o) Cassiopeiae, marks the northern end of the chain. NGC 185 is about 1° west of Omicron, and NGC 147 is 1° farther to the west-northwest. As mentioned above, NGC 147 is the more challenging target. On one seemingly clear night I could not detect NGC 147 with binoculars, though I could see its companion quite clearly. The following night NGC 147 suddenly appeared to stand out. Light pollution will certainly kill either object. Through the Genesis both galaxies can be viewed in the same low-power field. Two bright field stars bracket NGC 185 to the west and northeast. The galaxy is surprisingly easy to see at 23x, appearing as a slightly elliptical uniform glow that gradually brightens toward Deep-Sky Companions: The Caldwell Objects
the center. A faint outer halo is also suggested. At 72x the galaxy's core looks tight, though not stellar. The Γ-wide core also seems elongated and mottled. Christian Luginbuhl and Brian Skiff found that through a 6-inch telescope the eastern edge of the galaxy's halo has a "granular" texture and with a 10-inch the galaxy "looks like an unresolved globular cluster." NGC 147, however, is a demon at 23x. The region contains several clumps of field stars that mimic hazes, and only after careful plotting did I recognize NGC 147's true glow. (Do rely on both the chart and the photograph provided here to pinpoint it.) Dark skies are an absolute must for this dim galaxy. NGC 147 clearly looks more oval than NGC 185. Long and careful study of NGC 147 at 23x revealed hints of an elliptical center surrounded by a large, albeit faint, lens of light. Many times my eye caught the lens-shaped core of this ellipti- The Caldwell Objects 17 & 18 cal system quite clearly; at other times, a larger, extended halo appears to round it out. The outer halo is contained within a sharp diamondshaped pattern of bright field stars. At 72x the galaxy seems to scintillate with minute sparkles of light. Perhaps this is an illusion created by stars superposed on the galaxy. The more nights I spent observing this galaxy, the easier it became to pick out its faint glow on successive nights. This underscores how experience can make us better — and more efficient — observers. M31 and its four brightest companions (NGC 147, NGC 185, M32, and Ml 10) are all members of the larger Coma-Sculptor Cloud of galaxies. In a 1998 Astronomical Journal article Sidney van den Bergh (Dominion Astro-physical Observatory, Canada) stated that NGC 147 and NGC 185 probably form a stable binary system, orbiting M31 together like affectionate siblings. NGC 147's linear diameter is 12,000 light-years, while NGC 185 measures 11,000 light-years across; you could fit fully 10 galaxies the size of either dwarf across the length of the Great Andromeda spiral. In 1995 astronomer Paul Hodge (University of Washington) announced spectral evidence for some ongoing star formation in NGC 185. But in 1999 a trio led by David Martinez-Delgado (Astrophysical Institute of the Canaries, Spain) found that most of NGC 185's stars were formed at an early stage in the galaxy's evolution. "After that," these researchers write, "star formation proceeded at a low rate until the recent past, the age of the most recent traces of star formation activity detected in the galaxy being some 100 million years." They found no evidence for stars younger than a billion years beyond the galaxy's innermost few hundred light-years. "Since the larger concentration of stars of any age lies in the central part of a galaxy," Martinez-Delgado and his colleagues con- 77
Page 5 and 6:
DEEP-SKY COMPANIONS The Caldwell Ob
Page 7 and 8:
DEEP-SKY COMPANIONS The Caldwell Ob
Page 9 and 10:
Contents Foreword by Patrick Moore
Page 11 and 12:
to be more difficult than others, s
Page 13 and 14:
years of thought and observation ar
Page 15 and 16:
XII position, type, angular size, a
Page 17 and 18:
sky and share its splendors. There
Page 19 and 20:
CHAPTER 1 About This Book O N ONE S
Page 21 and 22:
times vog can back up and cause a s
Page 23 and 24:
when there is moisture in the air.
Page 25 and 26:
Herschel's original observations, p
Page 27 and 28:
we use today and to one another? I
Page 29 and 30:
SIMBAD (Set of identifications, Mea
Page 31 and 32:
Caldwell 26. The objects in the Cal
Page 33 and 34:
tion near the edges of the charts).
Page 35 and 36:
nights of observing. Unless otherwi
Page 37 and 38:
CHAPTER 2 The Caldwell Objects 1 1
Page 39 and 40:
Because of its location far from th
Page 41 and 42:
as strongly energized as would be e
Page 43 and 44: suggested by the patchiness of NGC
Page 45 and 46: 4 NGC 7023 Type: Reflection Nebula
Page 47 and 48: astronomers found direct evidence o
Page 49 and 50: and his contemporaries. Why then wa
Page 51 and 52: 6 Cat's Eye Nebula NGC 6543 Type: P
Page 53 and 54: Eighth-magnitude NGC 6543 is locate
Page 55 and 56: 7 NGC 2403 Type: Mixed Spiral Galax
Page 57 and 58: according to theory, the gas densit
Page 59 and 60: 8 Ghost’s Goblet NGC 559 Type: Op
Page 61 and 62: One other thing adds to the cluster
Page 63 and 64: RA: 22 h 56.8 m Dec: +62° 37' Mag:
Page 65 and 66: nebula is a near impossibility, eve
Page 67 and 68: 1 0 The Horseshoe Cluster NGC 663 T
Page 69 and 70: heart of the cluster, dividing it i
Page 71 and 72: appears to be the edge of a rapidly
Page 73 and 74: 1 2 NGC 6946 Type: Mixed Spiral Gal
Page 75 and 76: to the west by a row of similarly b
Page 77 and 78: the south-southwest. NGC 457, howev
Page 79 and 80: photographs. The cluster's bright "
Page 81 and 82: play begins at 8:00 p.m., when my e
Page 83 and 84: ightness by summing the contributio
Page 85 and 86: jewels. Here are sapphires, rubies,
Page 87 and 88: 15 outer shell falls upon the retin
Page 89 and 90: "knots" have also been noted by exp
Page 91 and 92: tight gathering of a half-dozen rou
Page 93: 1 7 NGC 147 Type: Elliptical Galaxy
Page 97 and 98: 1 9 Cocoon Nebula IC 5146 (nebula)
Page 99 and 100: trickle into the pool surrounding t
Page 101 and 102: 2 0 North America Nebula NGC 7000 T
Page 103 and 104: egion's size and mass extreme when
Page 105 and 106: The Caldwell Objects 20 87
Page 107 and 108: 2 1 Box Galaxy NGC 4449 Type: Irreg
Page 109 and 110: fuse but obvious glow of patchy lig
Page 111 and 112: qualifier—the word "light" — ha
Page 113 and 114: with a sheen of light, especially a
Page 115 and 116: 1003, NGC 1023, and NGC 1058 (a nic
Page 117 and 118: Way) that pop in and out of view as
Page 119 and 120: RA: 03 h 19 m 48 s Dec: +41° 30.7'
Page 121 and 122: Through the 4-inch, NGC 1275 is les
Page 123 and 124: (300,000 light-years), Pal 4 (360,0
Page 125 and 126: 26 Silver Needle Galaxy NGC 4244 Ty
Page 127 and 128: 2 7 Crescent Nebula NGC 6888 Type:
Page 129 and 130: Observatory, England) still lists a
Page 131 and 132: pie refractors and inefficient spec
Page 133 and 134: 29 NGC 5005 Type: Mixed Spiral Gala
Page 135 and 136: s h a edges. r p However, Christian
Page 137 and 138: ulars; challenge yourself and your
Page 139 and 140: NGC 7331 is extended much farther t
Page 141 and 142: away" stars escaped the confines of
Page 143 and 144: sweep the telescope in a north-sout
Page 145 and 146:
highly suspect by some. However, in
Page 147 and 148:
33 Network Nebula; Bridal Veil Nebu
Page 149 and 150:
A quarter-second later, the star en
Page 151 and 152:
under the dark skies of Seagrave Ob
Page 153 and 154:
35 NGC 4889 Type: Elliptical Galaxy
Page 155 and 156:
magnitude 12.2 some 18' to the east
Page 157 and 158:
36 NGC 4559 Type: Mixed Spiral Gala
Page 159 and 160:
Comae Berenices, the obvious northe
Page 161 and 162:
3 7 NGC 6885 Type: Open Cluster Con
Page 163 and 164:
pressed, stars of magnitude 6 to 11
Page 165 and 166:
of Herschel's telescope. W then e e
Page 167 and 168:
see the dark needle near the third
Page 169 and 170:
sion of a "thin flat ring of enormo
Page 171 and 172:
(which does not appear on Sky Atlas
Page 173 and 174:
not be found in planetary nebulae,
Page 175 and 176:
star in a large naked-eye triangle
Page 177 and 178:
4 0 NGC 3626 Type: Lenticular Galax
Page 179 and 180:
40 NGC 4546 in Virgo, NGC 4138 in C
Page 181 and 182:
Northern Hemisphere, and people cel
Page 183 and 184:
magnitude field star 2' to the nort
Page 185 and 186:
this state of affairs.) The Hyades
Page 187 and 188:
4 2 NGC 7006 Type: Globular Cluster
Page 189 and 190:
each square arcminute of its disk s
Page 191 and 192:
4 3 Electric Arc NGC 7814 Type: Spi
Page 193 and 194:
hook as my "train route." Start at
Page 195 and 196:
230 billion Suns and a physical dia
Page 197 and 198:
4 5 NGC 5248 Type: Mixed Spiral Gal
Page 199 and 200:
of the field. Those living under da
Page 201 and 202:
1" in a mere four days. Clearly, La
Page 203 and 204:
porarily) even the most practiced o
Page 205 and 206:
Page 207 and 208:
stragglers are stars that appear to
Page 209 and 210:
4 8 NGC 2775 Type: Spiral Galaxy (S
Page 211 and 212:
with a CCD camera — discovered a
Page 213 and 214:
this wreathlike network of dust and
Page 215 and 216:
fuzzy patch of light with the unaid
Page 217 and 218:
known as NGC 2244; and NGC 2239 sho
Page 219 and 220:
At a glance the two stars at the cl
Page 221 and 222:
On four plates taken with the Bruce
Page 223 and 224:
years. A total of 43 star-cluster c
Page 225 and 226:
5 2 NGC 4697 Type: Elliptical Galax
Page 227 and 228:
northeast of the sixth star in the
Page 229 and 230:
53 The Spindle NGC 3115 Type: Lenti
Page 231 and 232:
and the 100-inch telescopes atop Mo
Page 233 and 234:
Page 235 and 236:
emerge, followed by a diffuse outer
Page 237 and 238:
perfection than is actually the cas
Page 239 and 240:
jets, like a stream of water from t
Page 241 and 242:
5 6 Pac-Man Nebula NGC246 Type: Pla
Page 243 and 244:
the triple-alpha process, wherein t
Page 245 and 246:
5 7 Barnard's Galaxy NGC 6822 Type:
Page 247 and 248:
to show how the galaxy's western re
Page 249 and 250:
Page 251 and 252:
core and limber arms, which, he wro
Page 253 and 254:
esembles Jupiter . . . '" Smyth's f
Page 255 and 256:
years" and suggests amateurs monito
Page 257 and 258:
6 0 Ringtail Galaxy; Rataail Galaxy
Page 259 and 260:
war. X-ray images taken by the Rosa
Page 261 and 262:
W. Sinnott's NGC 2000.0 has a visua
Page 263 and 264:
62 Milkweed Seed Galaxy NGC247 Type
Page 265 and 266:
through the narrow haze. But give t
Page 267 and 268:
was more readily seen in binoculars
Page 269 and 270:
Society. Accepting that distance, w
Page 271 and 272:
any large telescope that can provid
Page 273 and 274:
ought it to our attention in the Fe
Page 275 and 276:
inch the cluster shows a pyramid of
Page 277 and 278:
NGC 253 is the brightest member of
Page 279 and 280:
magnitude stars, one just to the ea
Page 281 and 282:
6 6 NGC5694 Type: Globular Cluster
Page 283 and 284:
you see its core dancing? Its starl
Page 285 and 286:
cosmologist Halton Arp (Max-Planck
Page 287 and 288:
and kinked. All this detail is wrap
Page 289 and 290:
telescope. But seeing it takes more
Page 291 and 292:
streamers begin to appear, but they
Page 293 and 294:
tounding, because NGC 6302 is a mag
Page 295 and 296:
70 Southern Pinwheel NGC300 Type: S
Page 297 and 298:
would John Herschel suddenly fault
Page 299 and 300:
Dunlop discovered NGC 55 with his 9
Page 301 and 302:
even when crossing the meridian. Co
Page 303 and 304:
"nebulous clusters" (Class II); and
Page 305 and 306:
galaxy's disk and halo. NGC 2477 ap
Page 307 and 308:
condensed, almost to the very margi
Page 309 and 310:
The asymmetry remains at high power
Page 311 and 312:
other popular nickname, the Eight-B
Page 313 and 314:
longed look, the object displays a
Page 315 and 316:
times larger than the full Moon. In
Page 317 and 318:
emains of a globular cluster that w
Page 319 and 320:
he classified them accordingly. NGC
Page 321 and 322:
NGC 6231). Under averted vision the
Page 323 and 324:
7 7 Centaurus A NGC5128 Type: Pecul
Page 325 and 326:
Harvard College Observatory's 24-in
Page 327 and 328:
at 16 million light-years. If you s
Page 329 and 330:
78 NGC 6541 Type: Globular Cluster
Page 331 and 332:
seems to fragment into tiny stars,
Page 333 and 334:
sense, evinced by any known cluster
Page 335 and 336:
12th-magnitude double star. The clu
Page 337 and 338:
original with Bayer, but goes back
Page 339 and 340:
Omega Centauri is generally regarde
Page 341 and 342:
glitter all come to mind as the clu
Page 343 and 344:
shattered remains of their diminuti
Page 345 and 346:
It's a nice even disk of l0th-magni
Page 347 and 348:
with the fiery reddish light of hyd
Page 349 and 350:
nebulosity when he viewed the regio
Page 351 and 352:
the two jets of radio-wave-emitting
Page 353 and 354:
pair of tweezers. A fairly bright s
Page 355 and 356:
suggest that our universe may be on
Page 357 and 358:
8 5 Omicron Velorum Cluster IC2391
Page 359 and 360:
Nicolas Louis de Lacaille, however,
Page 361 and 362:
much sky as does the full Moon, tho
Page 363 and 364:
Page 365 and 366:
timates, making it 2 billion years
Page 367 and 368:
NGC 5822. Don't be surprised if you
Page 369 and 370:
89 S Normae Cluster NGC 6087 Type:
Page 371 and 372:
fact, if you look about 7' southwes
Page 373 and 374:
lowing night fell clear, when Hersc
Page 375 and 376:
NGC 2867 is a nitrogen-rich planeta
Page 377 and 378:
halfway between M37 in Auriga (200
Page 379 and 380:
9 2 Eta Carinae Nebula GC 3372 Type
Page 381 and 382:
anch of cold, dark material. Indeed
Page 383 and 384:
stretch 16 billion km from the cent
Page 385 and 386:
the object was known to some civili
Page 387 and 388:
east, and a dim lip of gas to the s
Page 389 and 390:
1 0 1 NGC 6744 Type: Barred Spiral
Page 391 and 392:
have been identified in NGC 6752's
Page 393 and 394:
ightest spiral arm(s) to the north,
Page 395 and 396:
his maiden voyage of discovery in 1
Page 397 and 398:
simply takes much too much effort t
Page 399 and 400:
Page 401 and 402:
very wide double of near-equal inte
Page 403 and 404:
went out and looked at the cluster
Page 405 and 406:
NGC 2516 is 60 million years young
Page 407 and 408:
and contains some 1,890 members, wh
Page 409 and 410:
9 8 Coalsack Cluster NGC 4609 Type:
Page 411 and 412:
it near the Swan? There is a still
Page 413 and 414:
with the naked eye is a challenge.
Page 415 and 416:
1 0 0 Lambda Centauri Cluster Colli
Page 417 and 418:
position updates to (2000.0) R.A. 1
Page 419 and 420:
Eta Carinae Nebula. But remember th
Page 421 and 422:
9th magnitude. Of the latter, 23 ha
Page 423 and 424:
103 1 0 3 Tarantula Nebula; True Lo
Page 425 and 426:
southern-sky explorer Abbe Nicolas
Page 427 and 428:
Page 429 and 430:
ters it has had thus far with the g
Page 431 and 432:
ly east of NGC 362 we find the magn
Page 433 and 434:
the eye ever inward and takes your
Page 435 and 436:
1 0 5 Southern Butterfly NGC 4833 T
Page 437 and 438:
stars"). Lacaille also likened NGC
Page 439 and 440:
is about 7' in length, and nearly 2
Page 441 and 442:
Page 443 and 444:
evealed a significant blue-straggle
Page 445 and 446:
ightest stars shine around 4th magn
Page 447 and 448:
egion looks cold and disturbing, no
Page 449 and 450:
The galaxy received some incidental
Page 451 and 452:
This entry is obviously in error, b
Page 453 and 454:
7 N G C 4 0 4 T y L p e n : G t a i
Page 455 and 456:
pointed her 7x35 binoculars toward
Page 457 and 458:
13 NGC 288 Type: Globular Cluster C
Page 459 and 460:
your telescope on Eta Sculptoris an
Page 461 and 462:
19 N G C 6 2 8 1 T y O p e C : n l
Page 463 and 464:
C Name Type Con. R.A. Dec Mag. Size
Page 465 and 466:
C Name Type Con. R.A. Dec Mag. Size
Page 467 and 468:
Appendix B Why Messier Did N o t i
Page 469 and 470:
A typical pattern for evening hunti
Page 471 and 472:
Earth turns, the cluster would clim
Page 473 and 474:
Initially Herschel made his living
Page 475 and 476:
of the heavens with it. For his swe
Page 477 and 478:
tube's front end. This meant that t
Page 479 and 480:
Star in Collo Ceti" about the star
Page 481 and 482:
years, Herschel would observe some
Page 483 and 484:
fluid, but added that ages of obser
Page 485 and 486:
Appendix D Photo Credits in order o
Page 487 and 488:
A Abell426, 101 Acrux, 388, 392, 39
Page 489 and 490:
index Caldwell 44, 173, 176-178 Cal
Page 491 and 492:
and nebulae, 271, 274, 362 and open
Page 493 and 494:
Hevelius, Johannes, 72, 81, 452 Hip
Page 495 and 496:
M103, 49-50, 58-59 M110, 77 MACHOs.
Page 497 and 498:
NGC 3324, 369 NGC 3372 (Caldwell 92
Page 499 and 500:
Perseus Cluster, 101 Phi Cas Cluste
Page 501 and 502:
Τ Tarantula Nebula (Caldwell 103),
show all

The Caldwell Objects

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?