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RA: 23h 49m 48s
Dec: +68° 02′ 0″
Ch: MSA:1057, U2:15, SA:3
Ref: SIMBAD, DAML02, Archinal&Hynes (2003)
Type: open cluster, 22m
Mag: B=?, V=11
Synonyms: H VII-055
Discovered in 1788 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a cluster of considerably small stars, iF, pretty rich and compressed, contains a vacancy in the middle." In the Philosophical Transactions, 1814, Herschel described it as "a pretty compressed cluster of very small stars; it is of an irregular figure, and has a vacancy in the middle. This appearance may be accounted for by supposing, for instance, three, four, or a greater number of preponderating attracting centres near each other, situated so as to inclose a certain space, the stars in which, then, cannot be accumulated, while the clustering power arising from the combined attractions will be exerted on the surrounding stars."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 11' and the class as 1 1 mU.
The RNGC (Sulentic and Tifft 1973) notes that this is a 10.0 mag open cluster.
Photo Index by Jim Lucyk: Vehrenberg's Atlas of DS Splendors (3ed) p11.
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.
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "11M; 15' diameter; 70-plus 12 thru 15M members; large and very, very faint; smaller, dimmer version of N7789 with about 1/10 the star count; bright star to SW is 5M SAO 20853; 1.5 degrees to ESE is cluster Ced-214."
15cm - lg mod f cl NE of m6 *. consp from general fld @ 50x as concen of f *s. 12' diam w/60 *s m12+. border irreg, but somewhat elong ~E-W. m7 * not far outside NE side; this is closer of two plotted on U2000 (where rel mags of the two are wrong). strong of 4-5 *s nr center. BS, 19Oct1992, Anderson Mesa.
25cm - lg, vf. on N side of br *. 20' diam w/20-30 *s res. gran bkgrnd haze.
30cm - really spread out for its size. 15' or so diam w/uneven sprinkling of *s m10.5+. *ism of 4-5 *s appears nebulous @ lox, but is res at hix.
The Messier objects
The Bennett objects
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