The Caldwell Objects

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13 1 3 E. T. Cluster; Phi Cas Cluster NGC 457 Type: Open Cluster Con: Cassiopeia RA:01 h 19.5 m Dec: +58° 17' Mag: 6.4 Diam: 20' Dist: indeterminate (see text) Disc: William Herschel, 1787 W. H ERSCHEL: [Observed 18 October 1787] A brilliant cluster of [bright] and very [faint] stars, considerably rich. (HVII-42) O F THE D OZENS OF OPEN CLUSTERS IN Cassiopeia, none inspires as many visual flights of fancy as NGC 457. Christian Luginbuhl and Brian Skiff rate it as "perhaps the most impressive of all the clusters in Cassiopeia," and Sky & Telescope's Alan M. MacRobert calls it "one of my favorites in the whole sky." Certainly NGC 457 is fast becoming one of the most popular showpieces at amateur gatherings. In his book Star-Hopping for Backyard Astronomers, MacRobert explains why: "This is one of those clusters that especially provoke the human tendency to see animals, faces, and monsters in random patterns." In photographs this roughly T-shaped pack of glittering suns looks like the stick figure of a man ready to greet you: two prominent stars at the cluster's southeastern end mark the figure's gaping eyes; two chains of stars on the northeastern and southwestern sides of the 58 GC / NGC: Cluster, bright, large, pretty rich, stars of magnitude 7, 8, and 10. cluster's tapered body extend outward like wideopen arms; and two isolated suns at the cluster's northwestern end mark the figure's comfortably spaced feet. The cluster looks like it is not only happy to see you but wants to give you a hug. Shining at magnitude 6.4, NGC 457 is Cassiopeia's third-brightest open cluster, following magnitude-4.4 Stock 2 (a little-known 1°wide cluster about 2° north-northwest of the Double Cluster's NGC 869) and Stock 5, whose brightest star is magnitude 4.9. Yet despite its prominence, NGC 457 is yet another one of those visual gems that tends to be lost in the shadow of fame surrounding a nearby Messier object, in this case M103. Both Μ103 and NGC 457 are in the Milky Way's Perseus Arm and can be found near Delta (δ) Cassiopeiae. M103 lies less than 1° northeast of Delta Cassiopeiae, while NGC 457 is 2° to Deep-Sky Companions: The Caldwell Objects
the south-southwest. NGC 457, however, hides in the glare of 5th-magnitude Phi (φ) Cassiopeiae. Not surprisingly, amateurs tend to point their telescopes more often to Μ103. But the celestial winds are fast changing. Classically, NGC 457 has been referred to as the Phi Cas Cluster. But this humdrum moniker fails to capture the cluster's spirit or to fire the observer's imagination. So, despite the fact that Robert Burnham Jr. spotlights NGC 457 in his Celestial Handbook, and despite repeated invitations from the late Walter Scott Houston to seek out the Phi Cas Cluster, interest in NGC 457 fell short of making it a national or international showpiece — until something magical happened. In 1982 Steven Spielberg introduced Ε. Τ The Extra-Terrestrial to the big screen. Five years later, NGC 457 mysteriously exploded onto the celestial stage. Amateurs began introducing NGC 457 to their peers, first byword of mouth, then through their telescopes set up under the shimmering Milky Way. By 1990 NGC 457 had become one of the preferred 13 telescopic targets at star parties across North America and, undoubtedly, in other parts of the world. I was first introduced to the cluster as recently as 1994 while attending StarFest, an annual summer gathering of amateur astronomers outside Toronto, Ontario. The sudden sensation can be traced back to 1987, though, when Tom Lorenzin and Tim Sechler compared NGC 457 with Spielberg's charismatic alien hob- bit in their book 1000+: The Amateur Astronomer's Field Guide to Deep Sky Observing. Of NGC 457 they write, "ET waves his arms at you, and winks!" A search of the pre-1987 literature reveals no widely recognized nickname other than "Phi Cas" for the cluster. As Ε. T. faded from the public scene, amateurs began personalizing the cluster. Over the years I have heard different telescope owners refer to NGC 457 as the Owl, Airplane, Stick Man, and Worry Doll Cluster. Some of these names may have been around a lot longer than Έ. T," but none of them had its universal charm or staying power. Ironically, Lorenzin and Sechler's popularization of the Ε. T. Cluster may be doing science a favor. The bright double star Phi Cassiopeiae (magnitudes 5.0 and 7.0; 134" separation) that marks E. T.'s eyes may not belong to the cluster. Brent Archinal notes that a 1961 article titled "Photometry of Stars in Galactic Cluster Fields" contains some of the first good combined photoelectric and photographic brightness measurements of stars in open clusters. "From the The Caldwell Objects 59
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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.
Page 25 and 26: Herschel's original observations, p
Page 27 and 28: we use today and to one another? I
Page 29 and 30: SIMBAD (Set of identifications, Mea
Page 31 and 32: Caldwell 26. The objects in the Cal
Page 33 and 34: tion near the edges of the charts).
Page 35 and 36: nights of observing. Unless otherwi
Page 37 and 38: CHAPTER 2 The Caldwell Objects 1 1
Page 39 and 40: Because of its location far from th
Page 41 and 42: as strongly energized as would be e
Page 43 and 44: suggested by the patchiness of NGC
Page 45 and 46: 4 NGC 7023 Type: Reflection Nebula
Page 47 and 48: astronomers found direct evidence o
Page 49 and 50: and his contemporaries. Why then wa
Page 51 and 52: 6 Cat's Eye Nebula NGC 6543 Type: P
Page 53 and 54: Eighth-magnitude NGC 6543 is locate
Page 55 and 56: 7 NGC 2403 Type: Mixed Spiral Galax
Page 57 and 58: according to theory, the gas densit
Page 59 and 60: 8 Ghost’s Goblet NGC 559 Type: Op
Page 61 and 62: One other thing adds to the cluster
Page 63 and 64: RA: 22 h 56.8 m Dec: +62° 37' Mag:
Page 65 and 66: nebula is a near impossibility, eve
Page 67 and 68: 1 0 The Horseshoe Cluster NGC 663 T
Page 69 and 70: heart of the cluster, dividing it i
Page 71 and 72: appears to be the edge of a rapidly
Page 73 and 74: 1 2 NGC 6946 Type: Mixed Spiral Gal
Page 75: to the west by a row of similarly b
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)
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
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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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