The Caldwell Objects

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24 24 Perseus A NGC 1275 Type: Peculiar Galaxy Con: Perseus 100 Deep-Sky Companions: The Caldwell Objects
RA: 03 h 19 m 48 s Dec: +41° 30.7' Mag: 11.9 Dim: 3.2' x 2.3' SB: 13.9 Dist: 230 million light-years Disc: Heinrich Louis d'Arrest, mentioned in the 1867 Siderum Nebulosorum Observationes Havnienses H ERSCHEL: None. GC: None. NGC 1275 is THE BRIGHTEST AND MOST CEN-tral member of the Perseus Cluster of galaxies, a dense nest of some 12,000 systems roughly 230 million light-years distant — four times farther from us than the far better known and easier-toobserve Virgo Cluster. To see the Perseus Cluster, which also is known as Abell 426, we must peer through a thicket of stars and dust in the Milky Way's outer reaches. By penetrating this thicket with radio telescopes, astronomers have discovered that NGC 1275 and its family are cutting through a fog of intergalactic material; this is evidenced by long "wakes" of plasma trailing several of the cluster's galaxies. The intergalactic fog was probably ejected over the eons by the active nuclei in the cluster's feistier systems, or torn free from spirals passing near the cluster's dense core. As with many spherical galaxy clusters rich in energetic ellipticals, the Perseus Cluster is also a strong emitter of X-rays. Four-fifths of the cluster's X-ray energy emanates from gases spread throughout the 3-million-light-year-wide cluster; the remainder comes from NGC 1275 itself. NGC 1275 long has been known as a strong source of radio emission. It is listed in the Third Cambridge Catalogue of radio sources as 3C 84; early radio astronomers referred to it simply as Perseus A. In addition, Carl K. Seyfert included it in his 1943 list of galaxies that display exceptionally bright or starlike nuclei. In photographs taken with the powerful 200-inch The Caldwell Objects NGC: Faint, small in angular size. 24 telescope on Palomar Mountain, NGC 1275's nucleus appears very tight, almost stellar. The galaxy's overall white-light appearance is that of a lenticular or elliptical system. A black "scratch" can be seen zigzagging across the galaxy's northern halo, and deep red-light images show a system of twisted filaments radiating in all directions. In a humorous way, these filaments suggest a child's drawing of an explosion in a spaghetti factory. The galaxy's filamentary "noodles" are fleeing into space with velocities on the order of 2,400 km per second. The enigmatic "scratch" has two parts: a bright streak that juts to the northwest before cutting sharply to the north, and a disjointed arc of matter that hugs the galaxy to the north, spirals to the east, then curves gently south. Bright ΗII regions and dark dust patches line both features. If we can free our imaginations and see this galaxy in three dimensions, the "scratch" looks like the flailing arms of an unseen spiral galaxy whose body has sailed obliquely into NGC 1275's "mouth." That scenario, in fact, is just what radio data suggest. As early as 1957 Walter Baade and Rudolph L. Minkowski proposed that NGC 1275 is an interacting pair of galaxies. The bright compact body appears to be that of an elliptical or lenticular galaxy, while most of the dust patches seem to be associated with the arms of a spiral system moving through NGC 1275 at a speed of 3,000 km per second. Tidal interactions have distorted the spiral's shape and may have ripped free the curved "tail" of stars to the east. 101
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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
Page 67 and 68: 1 0 The Horseshoe Cluster NGC 663 T
Page 69 and 70: heart of the cluster, dividing it i
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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
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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)
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
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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: Way) that pop in and out of view as
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
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Page 133 and 134: 29 NGC 5005 Type: Mixed Spiral Gala
Page 135 and 136: s h a edges. r p However, Christian
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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
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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
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Page 167 and 168: 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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5 4 NGC 2506 Type: Open Cluster Con
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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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