The Caldwell Objects

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5 5 IC 342 Type: Mixed Spiral Galaxy (SABcd) Con: Camelopardalis RA: 03 h 46.8 m Dec: +68° 06' Mag: 8.4; 7.9 (O'Meara) Dim: 16.1' χ 15.5' SB: 15.0 Dist: 13 million light-years Disc: William F Denning, . ~1890 H ERSCHEL: None. GC/NGC: None. IC: Pretty bright, very small in angular size, a star of 12th magnitude close to the north. A LTHOUGH MANY OF THE BIGGEST AND brightest deep-sky objects visible from the Northern Hemisphere — such as the Great Orion Nebula (M42), the Andromeda Nebula (M31), and the Pleiades (M45) — can be found in the Messier Catalog, some seemingly obvious telescopic objects are conspicuous by their absence. Of course, the Double Cluster in Perseus is the most glaring omission (see Appendix B). Another is the 8th-magnitude spiral galaxy IC 342 in Camelopardalis — one of many surprises you'll find in the Caldwell Catalog. IC 342 is a moderately open, clumpy, lowsurface-brightness spiral whose classification suggests a barred galaxy in transition. William F. Denning first spied the galaxy's sharp central glow and amorphous halo around 1890. But the spiral nature of the "nebula" remained unnoticed until Edwin P Hubble . and Milton L. Humason noted, in 1934, the galaxy's beautiful pinwheel pattern on plates taken from California's Mount Wilson. In shape and form IC 342 looks similar to the open-faced spirals M74 in Pisces and M101 in Ursa Major. Quantitatively, too, the three galaxies share comparable visual characteristics. IC 342's apparent diameter of 16' is about midway between that of M74 (10' across) and M101 (29'). IC 342 is a full magnitude brighter than M74 and half a magnitude fainter than M101. And IC 342's surface brightness (15.0 magnitudes per square arcminute) nearly matches those of M74 (14.4) and M101 (14.8). These data clearly suggest that IC 342 should have been within the visual range of Messier 30 Deep-Sky Companions: The Caldwell Objects
and his contemporaries. Why then was it not noticed until the late 19th century? Perhaps its anonymity resulted from the combination of IC 342's far-northern declination (+68°, an unlikely region for comet hunting), low surface brightness, and isolation (being in a region devoid of any especially bright stars or conspicuous asterisms). Unfortunately for us, IC 342 lies only 11° above the plane of our galaxy, where dense gas and dust dim the extragalactic spiral's light by nearly 3 magnitudes. Does that mean the galaxy is not worth investigating through small instruments? In his famous Celestial Handbook, Robert Burnham Ir. certainly gives that impression. He writes that IC 342 is "difficult for small telescopes" and while it "may be observed in an 8-inch glass under good conditions," it "appears as a small fuzzy 12th-magnitude The Caldwell Objects 5 nucleus surrounded by a very large and faint hazy glow." This may be accurate for a view through an 8inch telescope at moderately high power, which would diminish the view of such a large, low-surfacebrightness object. But the beauty of IC 342 can be appreciated in a richfield telescope with a low-power eyepiece. Roger Clark suggests that optimum magnifications for detecting IC 342 are 14x with a 4-inch telescope and 27x with an 8-inch. Under a very dark sky, IC 342 is easily seen in 7x35 binoculars. Just look 3¼° south of 4.6-magnitude Gamma (γ) Camelopardalis for a large, diffuse glow. Nothing else of that nature is within several degrees of your target. The galaxy looks so obvious in binoculars that I have tried to detect it with the unaided eye but without success. I would not be surprised, however, if someone with younger eyes does see it without optical aid. I'm also suspicious of IC 342's listed magnitude of 8.4 and believe that it may be at least a half magnitude brighter. The galaxy's position against the outer reaches of the northern Milky Way adds to the visual splendor; unlike M74, which is a large and dim glow in a star-poor region of the sky, IC 342 is seen against a sky background littered with starlight. At 23x the galaxy's core looks like a 12thmagnitude star trapped in a tight cocoon of nebulosity just south of a pair of similarly bright stars. Even at that low power there are immediate suggestions of appendages indicative of spiral structure. By scanning the field while sitting in a relaxing position, I was able to trace out three major spiral arms to nearly 31
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: astronomers found direct evidence o
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 and 94: 1 7 NGC 147 Type: Elliptical Galaxy
Page 95 and 96: the center. A faint outer halo is a
Page 97 and 98: 1 9 Cocoon Nebula IC 5146 (nebula)
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trickle into the pool surrounding t
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2 0 North America Nebula NGC 7000 T
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egion's size and mass extreme when
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The Caldwell Objects 20 87
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2 1 Box Galaxy NGC 4449 Type: Irreg
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fuse but obvious glow of patchy lig
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qualifier—the word "light" — ha
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with a sheen of light, especially a
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1003, NGC 1023, and NGC 1058 (a nic
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Way) that pop in and out of view as
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RA: 03 h 19 m 48 s Dec: +41° 30.7'
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Through the 4-inch, NGC 1275 is les
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(300,000 light-years), Pal 4 (360,0
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26 Silver Needle Galaxy NGC 4244 Ty
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2 7 Crescent Nebula NGC 6888 Type:
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Observatory, England) still lists a
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pie refractors and inefficient spec
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29 NGC 5005 Type: Mixed Spiral Gala
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s h a edges. r p However, Christian
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ulars; challenge yourself and your
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NGC 7331 is extended much farther t
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away" stars escaped the confines of
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sweep the telescope in a north-sout
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highly suspect by some. However, in
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33 Network Nebula; Bridal Veil Nebu
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A quarter-second later, the star en
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under the dark skies of Seagrave Ob
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35 NGC 4889 Type: Elliptical Galaxy
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magnitude 12.2 some 18' to the east
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36 NGC 4559 Type: Mixed Spiral Gala
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Comae Berenices, the obvious northe
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3 7 NGC 6885 Type: Open Cluster Con
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pressed, stars of magnitude 6 to 11
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of Herschel's telescope. W then e e
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see the dark needle near the third
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sion of a "thin flat ring of enormo
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(which does not appear on Sky Atlas
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not be found in planetary nebulae,
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star in a large naked-eye triangle
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4 0 NGC 3626 Type: Lenticular Galax
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40 NGC 4546 in Virgo, NGC 4138 in C
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Northern Hemisphere, and people cel
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magnitude field star 2' to the nort
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this state of affairs.) The Hyades
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4 2 NGC 7006 Type: Globular Cluster
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each square arcminute of its disk s
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4 3 Electric Arc NGC 7814 Type: Spi
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hook as my "train route." Start at
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230 billion Suns and a physical dia
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4 5 NGC 5248 Type: Mixed Spiral Gal
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of the field. Those living under da
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1" in a mere four days. Clearly, La
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porarily) even the most practiced o
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stragglers are stars that appear to
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4 8 NGC 2775 Type: Spiral Galaxy (S
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with a CCD camera — discovered a
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this wreathlike network of dust and
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fuzzy patch of light with the unaid
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known as NGC 2244; and NGC 2239 sho
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At a glance the two stars at the cl
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On four plates taken with the Bruce
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years. A total of 43 star-cluster c
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5 2 NGC 4697 Type: Elliptical Galax
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northeast of the sixth star in the
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53 The Spindle NGC 3115 Type: Lenti
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and the 100-inch telescopes atop Mo
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emerge, followed by a diffuse outer
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perfection than is actually the cas
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jets, like a stream of water from t
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5 6 Pac-Man Nebula NGC246 Type: Pla
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the triple-alpha process, wherein t
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5 7 Barnard's Galaxy NGC 6822 Type:
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to show how the galaxy's western re
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core and limber arms, which, he wro
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esembles Jupiter . . . '" Smyth's f
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years" and suggests amateurs monito
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6 0 Ringtail Galaxy; Rataail Galaxy
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war. X-ray images taken by the Rosa
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W. Sinnott's NGC 2000.0 has a visua
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62 Milkweed Seed Galaxy NGC247 Type
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through the narrow haze. But give t
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was more readily seen in binoculars
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Society. Accepting that distance, w
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any large telescope that can provid
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ought it to our attention in the Fe
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inch the cluster shows a pyramid of
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NGC 253 is the brightest member of
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magnitude stars, one just to the ea
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6 6 NGC5694 Type: Globular Cluster
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you see its core dancing? Its starl
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cosmologist Halton Arp (Max-Planck
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and kinked. All this detail is wrap
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telescope. But seeing it takes more
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streamers begin to appear, but they
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tounding, because NGC 6302 is a mag
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70 Southern Pinwheel NGC300 Type: S
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would John Herschel suddenly fault
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Dunlop discovered NGC 55 with his 9
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even when crossing the meridian. Co
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"nebulous clusters" (Class II); and
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galaxy's disk and halo. NGC 2477 ap
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condensed, almost to the very margi
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The asymmetry remains at high power
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other popular nickname, the Eight-B
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longed look, the object displays a
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times larger than the full Moon. In
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emains of a globular cluster that w
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he classified them accordingly. NGC
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NGC 6231). Under averted vision the
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7 7 Centaurus A NGC5128 Type: Pecul
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Harvard College Observatory's 24-in
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at 16 million light-years. If you s
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78 NGC 6541 Type: Globular Cluster
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seems to fragment into tiny stars,
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sense, evinced by any known cluster
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12th-magnitude double star. The clu
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original with Bayer, but goes back
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Omega Centauri is generally regarde
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glitter all come to mind as the clu
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shattered remains of their diminuti
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It's a nice even disk of l0th-magni
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with the fiery reddish light of hyd
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nebulosity when he viewed the regio
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the two jets of radio-wave-emitting
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pair of tweezers. A fairly bright s
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suggest that our universe may be on
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8 5 Omicron Velorum Cluster IC2391
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Nicolas Louis de Lacaille, however,
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much sky as does the full Moon, tho
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timates, making it 2 billion years
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NGC 5822. Don't be surprised if you
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89 S Normae Cluster NGC 6087 Type:
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fact, if you look about 7' southwes
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lowing night fell clear, when Hersc
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NGC 2867 is a nitrogen-rich planeta
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halfway between M37 in Auriga (200
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9 2 Eta Carinae Nebula GC 3372 Type
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anch of cold, dark material. Indeed
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stretch 16 billion km from the cent
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the object was known to some civili
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east, and a dim lip of gas to the s
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1 0 1 NGC 6744 Type: Barred Spiral
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have been identified in NGC 6752's
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ightest spiral arm(s) to the north,
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his maiden voyage of discovery in 1
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simply takes much too much effort t
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very wide double of near-equal inte
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went out and looked at the cluster
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NGC 2516 is 60 million years young
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and contains some 1,890 members, wh
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9 8 Coalsack Cluster NGC 4609 Type:
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it near the Swan? There is a still
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with the naked eye is a challenge.
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1 0 0 Lambda Centauri Cluster Colli
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position updates to (2000.0) R.A. 1
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Eta Carinae Nebula. But remember th
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9th magnitude. Of the latter, 23 ha
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103 1 0 3 Tarantula Nebula; True Lo
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southern-sky explorer Abbe Nicolas
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ters it has had thus far with the g
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ly east of NGC 362 we find the magn
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the eye ever inward and takes your
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1 0 5 Southern Butterfly NGC 4833 T
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stars"). Lacaille also likened NGC
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is about 7' in length, and nearly 2
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evealed a significant blue-straggle
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ightest stars shine around 4th magn
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egion looks cold and disturbing, no
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The galaxy received some incidental
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This entry is obviously in error, b
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7 N G C 4 0 4 T y L p e n : G t a i
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pointed her 7x35 binoculars toward
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13 NGC 288 Type: Globular Cluster C
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your telescope on Eta Sculptoris an
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19 N G C 6 2 8 1 T y O p e C : n l
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C Name Type Con. R.A. Dec Mag. Size
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C Name Type Con. R.A. Dec Mag. Size
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Appendix B Why Messier Did N o t i
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A typical pattern for evening hunti
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Earth turns, the cluster would clim
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Initially Herschel made his living
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of the heavens with it. For his swe
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tube's front end. This meant that t
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Star in Collo Ceti" about the star
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years, Herschel would observe some
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fluid, but added that ages of obser
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Appendix D Photo Credits in order o
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A Abell426, 101 Acrux, 388, 392, 39
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index Caldwell 44, 173, 176-178 Cal
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and nebulae, 271, 274, 362 and open
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Hevelius, Johannes, 72, 81, 452 Hip
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M103, 49-50, 58-59 M110, 77 MACHOs.
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NGC 3324, 369 NGC 3372 (Caldwell 92
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Perseus Cluster, 101 Phi Cas Cluste
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Τ Tarantula Nebula (Caldwell 103),
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The Caldwell Objects

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