The Caldwell Objects

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63 to the scrutiny of amateur telescopes? My 4-inch seems to perform just fine on it at 23x. The first impression I got was that of a ghastly, pale ring of ashen light trapped within a triangle of 10.0- to 11.5-magnitude stars. The northwestern and southwestern stars each have a roughly 12.5magnitude companion separated by some 3'. (The brighter member of the southwestern pair is a fine double star in its own right, though it is best seen at higher magnification.) The triangle's third star lies just to the east of the nebula and shines at about magnitude 11.5, though it looks much fainter in photographs. With averted vision, the Helix's edges appear sharply defined. The northwestern side looks thinner than the southeastern side. Look for two enhancements in the luminous ring; one, to the northeast, connects to another, to the southwest. Try averted vision and see if these enhancements don't look like a pair of ghostly lips blowing you a kiss. With time, they appear mottled. The central cavity is quite transparent at low power. With a lot of patience you can see a fair amount of detail in the nebula at 72x (the object all but disappears with anything much 252 higher). First, I suggest you draw the surrounding star field before you go out; use the photograph below as a guide. That way you can pencil in nebular details without having to worry about getting the stars right; you can later tweak the sizes of the stars to reflect their relative brightnesses in the eyepiece. Now, working your way from the inside out, first check the "hole" for the magnitude-13.4 central star. It takes time for me to see it with my 4-inch, but there's no mistaking it once I do. If you have a sturdy mount, try looking for the central star with a higher magnification, say 140x. You will not see the nebulosity, but that's not what you're after at this point. Next look for the dense inner ring with 72x; it's the brightest part of the entire nebula. The ring contains several background stars and nebulous enhancements, especially to the northwest and southwest. To see the outermost nebulosity, try placing the Helix outside your field of view, then slowly bringing it back (the eye is more sensitive to light in motion). The nebula's broad eastern portion has a dim but sharp edge that is not difficult to spot in this way. The most challenging part of the nebula lies to the west, where a tail of gas appears to curve northward from the southern rim of the inner annulus. This tail meets the 10th-magnitude star bordering the nebula to the northwest, then curves back to the inner ring and connects with its northern edge. This last wisp of gas is the most difficult portion to see, but if you can trace it you will have mapped the Helix's full "double twist." If you fail to see this dim wisp, return to low power and look again. Low power will condense its light and make it more apparent. Do not expect to see all this detail at once with a 4-inch. My drawing at upper left is a composite of the Helix as seen at low, medium, and high power. I have a special challenge for the owner of Deep-Sky Companions: The Caldwell Objects
any large telescope that can provide a wide field of view. Almost all photographs of the Helix reveal traces of the cometlike structures; yet I have heard no visual reports of them. I believe that if these structures can be photographed, they can be seen. So there's your challenge. Meanwhile, Arizona amateur Steve Coe has another: "If you are looking for a real observing challenge for your next observing session, the Helix can supply a toughie! The 63 picture of the Helix on page 195 in Robert Burnham Jr.'s Celestial Handbook shows a very faint edge-on galaxy at the edge of the Helix Nebula. It is located at the end of the Helix that opens up near a pretty bright star [the aforementioned l0th-magnitude star]. Using the 17.5inch on a night I rated 9/10 at 8,000 feet in the Central Mountains of Arizona, I could just pick it out at 300x." (This tiny galaxy is arrowed in the photograph above.) Good luck! The Caldwell Objects 253
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DEEP-SKY COMPANIONS The Caldwell Ob
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DEEP-SKY COMPANIONS The Caldwell Ob
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Contents Foreword by Patrick Moore
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to be more difficult than others, s
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years of thought and observation ar
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XII position, type, angular size, a
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sky and share its splendors. There
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CHAPTER 1 About This Book O N ONE S
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times vog can back up and cause a s
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when there is moisture in the air.
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Herschel's original observations, p
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we use today and to one another? I
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SIMBAD (Set of identifications, Mea
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Caldwell 26. The objects in the Cal
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tion near the edges of the charts).
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nights of observing. Unless otherwi
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CHAPTER 2 The Caldwell Objects 1 1
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Because of its location far from th
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as strongly energized as would be e
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suggested by the patchiness of NGC
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4 NGC 7023 Type: Reflection Nebula
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astronomers found direct evidence o
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and his contemporaries. Why then wa
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6 Cat's Eye Nebula NGC 6543 Type: P
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Eighth-magnitude NGC 6543 is locate
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7 NGC 2403 Type: Mixed Spiral Galax
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according to theory, the gas densit
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8 Ghost’s Goblet NGC 559 Type: Op
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One other thing adds to the cluster
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RA: 22 h 56.8 m Dec: +62° 37' Mag:
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nebula is a near impossibility, eve
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1 0 The Horseshoe Cluster NGC 663 T
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heart of the cluster, dividing it i
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appears to be the edge of a rapidly
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1 2 NGC 6946 Type: Mixed Spiral Gal
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to the west by a row of similarly b
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the south-southwest. NGC 457, howev
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photographs. The cluster's bright "
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play begins at 8:00 p.m., when my e
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ightness by summing the contributio
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jewels. Here are sapphires, rubies,
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15 outer shell falls upon the retin
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"knots" have also been noted by exp
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tight gathering of a half-dozen rou
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1 7 NGC 147 Type: Elliptical Galaxy
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the center. A faint outer halo is a
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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
Page 219 and 220: At a glance the two stars at the cl
Page 221 and 222: On four plates taken with the Bruce
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Page 229 and 230: 53 The Spindle NGC 3115 Type: Lenti
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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
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Page 251 and 252: core and limber arms, which, he wro
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Page 257 and 258: 6 0 Ringtail Galaxy; Rataail Galaxy
Page 259 and 260: war. X-ray images taken by the Rosa
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Page 265 and 266: through the narrow haze. But give t
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Page 269: Society. Accepting that distance, w
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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
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Page 295 and 296: 70 Southern Pinwheel NGC300 Type: S
Page 297 and 298: would John Herschel suddenly fault
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Page 309 and 310: The asymmetry remains at high power
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Page 315 and 316: times larger than the full Moon. In
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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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9 5 NGC 6025 Type: Open Cluster Con
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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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