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RA: 21h 44m 0s
Dec: +53° 43′ 0″
Ch: MSA:1087, U2:57, SA:3
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 13m
Mag: B=10.54, V=9.7
Synonyms: H VII-040
Discovered in 1787 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a cluster of small stars of several sizes, 3' or 4' diameter, pretty rich like a forming one."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 3.2' and the class as 2 2 p.
Photo Index by Jim Lucyk: Observer's Guide (Astro Cards) 9-10/87 p28.
The RNGC (Sulentic and Tifft 1973) notes that this is a 11.5 mag open cluster.
Houston observed with a 10-inch at 60x and saw half a dozen stars surrounded by a glow at the threshold of visibility. Increasing the power to 150x with a barlow added about 15 stars, but, surprisingly, the glow remained. He also wrote: "this cluster is scarcely as big in angular size as many planetary nebulae. It needs 100x to 150x in any telescope. Its brighter members remined me of a tiny replica of Auriga, with a background haze of fainter suns."
Listed by the Herschel Club, described as "some 20 stars were counted, very loose and poor. 8-inch, 43x."
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "9M; 2' diameter; 30-plus 10M and dimmer members; small, compressed and memorable! brighter members make small pentagon."
WDS: pair on SE = h3058: 11.1,12.2; 8".7; 264.
6cm - vsim to -27. sm w/br * on SE edge. sev sparkles.
15cm - sim to N7031 just obs'd in that it is a sm circlet of rel br *s in dk area. 140x: 15 *s incl m10 * on E side of circlet, others fntr. m12.0 approx = pair on W side. another f pair 10' W. BS, 21Jun1991, Anderson Mesa.
25cm - 15 *s, ten of which in a circlet incl two pairs, a triplet and three single *s. 2' diam, roughly octagonal.
30cm - neat, sm. circlet of about nine *s incl reddish br one, is like jeweled necklace hanging from cl which is about the NW side of the circlet. 10 *s plus circlet, all vf.
Alldays (22.50S, 20.12E, 770m).
12-inch f/10 SCT (95x, 218x)
This lovely small grouping share its space very cosy. Form a sort of ring in shape with various coloured stars. One outstanding yellow star on the SE tip. Barely 3' in size if I compare with the field of view. Clusters shows a teensy ring of five stars with one star acting like the Yellow jewel in the engagement ring and also being brighter than the rest.
The Messier objects
The Bennett objects
The Caldwell list
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