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RA: 00h 43m 36s
Dec: +61° 46′ 0″
Ch: MSA:49, U2:16, SA:1
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 31pn
Mag: B=7.43, V=7
Discovered by Caroline Herschel.
Synonyms: H VIII-078
Discovered in 1788 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a cluster of very coarsely scattered large stars, take up 15 or 20'. Discovered by Caroline Herschel in 1784."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "fine cluster, somewhat like the letter W; half way from Gamma to Kappa."
Trumpler (Lick Obs Bulletin, Vol 14, No. 420) gives the diameter as 14' and the class as III 1 p.
Vorontsov-Velyaminov, B. (1925) "Catalogue of integrated magnitudes of star clusters", Astron. Nach. 226.195. Comparing the brightness of the cluster with the extrafocal images of stars, he estimates the magnitude as 7.56.
Photo index by Jim Lucyk: Deep Sky #8 Fa84 p27.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.0 mag open cluster.
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes "7M; 14' diameter; w-shaped group just NW of midway between Gamma and Kappa CAS; 20-plus 9M and dimmer members"
Listed by the Herschel Club, described as "a large cluster, counted some 21 associated members. A nice arrangement of stars. Very rich and fanning out in all directions. 8-inch, 48x."
Houston notes that this cluster is a longtime favourite of amateurs. Estimates of the diameter range from 12' to 25'. He adds that about half of the score of stars seen in small scopes are brighter than magnitude 10.
8cm - easily ident and well res, incl string on E, but not really consp as cl. BS, 13Aug1983, Anderson Mesa.
15cm - br but sparse 10' diam cl W of string of five m9 *s plotted on U2000. bkgrnd nrly blank, few f *s in cl. 140x shows about 20 *s in main body W of S end of string, half of them m9-10, rest pretty f. BS, 10Dec1990, Anderson Mesa.
25cm - 8'x6'. 18 *s mostly m9. even spacing btwn *s. not condensed.
- 16' diam w/five m8.5 *s lined up N-S on E. cl loose w/20 *s to m13.5.
30cm - 30 *s counted in 20' fld, brtr ones come to 14. elong E-W. string to E noted.
Observing site: Little Tycho Observatory
[0h 43m 24s, 61° 47m 0s] A very loose grouping of a few 8-9mv stars with an almost invisible core of 11-12mv stars. Lackluster.
The Messier objects
The Bennett objects
The Caldwell list
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