The Caldwell Objects

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Malcolm J. Thomson of Santa Barbara, California, describes the planetary as having a curved dark area between the central star and the following (eastward) edge. Through a 12-inch reflector, Christian Luginbuhl and Brian Skiff also viewed this dark region as well as an uneven edge on the nebula's western limb. Images taken through large telescopes and various filters reveal greater details in the Blinking Planetary. Especially noteworthy is the presence of a dense elliptical inner disk and knots at either end of that ellipse embedded in an outer halo. Would an Oxygen-III filter help amateurs bring out further details in NGC 6826 with their moderate-sized telescopes? I have not seen any reports of this. In 1995 Austrian astronomer Gerald Handler (Vienna University) announced that several relatively cool central stars of planetary nebulae, including those of NGC 6826 and NGC 6543 (Caldwell 6), show brightness variations of up to 0.2 magnitude on time scales of several hours to days. Amateurs with access to large telescopes and photometers might want to try their hands at recording these fluctuations. With Mira, his 16-inch Dobsonian, Jay McNeil has recently made one of the most detailed visual studies ever performed on the Blinking Planetary. He spent a total of about 2½ hours studying and drawing this object on two separate nights. On both nights the seeing was better than 1" and the transparency quite good, and the most pleasant and revealing view came at 586x. A power of 855x was also used at times to glimpse even smaller, more intricate details. According to McNeil, the nebula's brightest part was an elliptical oval (roughly 30" x 25"), oriented east-southeast and west-northwest, around the central star. This oval ring was mottled near the tips of its major axis and, during moments of excellent seeing, McNeil detected a sharp 70 15 inner ring about 10" in diameter. The area between the inner ring and the central star was darker than any other part of the nebula but not as dark as the background sky. McNeil also sighted the southeastern FLIER complex, which appeared as a very slightly nonstellar nebulous "knot" less than 3" in extent at the very edge of the outer envelope's easternmost point. "With a Lumicon Deep-Sky filter applied at 586x," he says, "this [feature] became nearly as apparent as the nebula's filtered nucleus at times." He also sighted the much fainter northwestern FLIER complex, which looked like a diffuse knot. At 855x shell structure within the nebula seemed quite complex, and the view was reminiscent of NGC 7009, the Saturn Nebula (Caldwell 55). At times the FLIERs extended very slightly beyond the nebula's bright outer envelope "as if the very edges of the major axis consisted of small 'nipples.'" With extreme averted vision a low-surface-brightness halo surrounded the entire structure out to 35". The individual FLIERs or Deep-Sky Companions: The Caldwell Objects
"knots" have also been noted by expert observer Alister Ling in an 8-inch f/6 telescope at 500x. So they are definitely within the reach of deep-sky observers. The key is the proper use of extremely high magnification — and patience. The Caldwell Objects 15 71
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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
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: 15 outer shell falls upon the retin
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)
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
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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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