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RA: 06h 38m 34.4s
Dec: +10° 53′ 24″
Ch: MSA:203, U2:182, SA:12
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 21pn
Mag: B=?, V=10.8
Also known as Collinder 108, this open cluster is described in the NGC as "considerably rich, extremely compressed, irregular shape, stars extremely small." Darnley Wright calls this cluster "a rich cluster of about 25 stars."
Synonyms: H VI-028
Discovered in 1787 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a cluster of extremely compressed and eS stars, considerably rich, iF, the following and most compressed part round."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 3.5' and the class as 1 3 m.
Photo Index by Jim Lucyk: Vehrenberg's Atlas of Galactic Neb-1 (on photo p103).
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
The RNGC (Sulentic and Tifft 1973) notes that this is a 11.0 mag open cluster.
MacRoberts writes "I couldn't see a trace of it in the 6-inch [45x] through my suburban light pollution." A 10-inch under dark skies, as used by Luginbuhl and Skiff, reveals it as "granular to partially resolved at 200x." The cluster has 25 member stars, the brightest being 14th magnitude, and is spread out over 4.5', giving it a combined magnitude of 11.0.
Steve Coe, observing with a 13" f/5.6, notes: "is bright, pretty large, round, rich and very compressed at 100X. I resolved 15 stars against a very grainy backround at 220X. This is a nice, tight cluster, try some power."
Steve Coe (Glendale, Arizona, USA) observing with a 13.1-inch f/5.6 reflector, writes in The Webb Society Nebulae and Clusters Section Report No. 11, January 1993: "Bright, pretty large, rich, very compressed, and round at x100. Fifteen stars resolved against a very grainy background at x220. This is a nice, tight cluster. Try some power."
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "11M; 4' diameter; samll and rich; 25-plus 12M and dimmer members; difficult in 8-inch; easier with much larger aperture."
Observing site: Pinnacles overlook
[6h 38m 36s, 10° 53m 0s] A small, faint cluster of a few 11.5 mv stars and a cloud of around 50 14mv stars.
The Messier objects
The Bennett objects
The Caldwell list
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