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RA: 07h 38m 23s
Dec: +21° 34′ 24″
Ch: MSA:152, U2:139, SA:5
Ref: SIMBAD, DAML02, Archinal&Hynes (2003)
Type: open cluster, 11r
Mag: B=9, V=8.3
Synonyms: H VI-001
Discovered in 1785 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a beautiful cluster of many large and compressed small stars, about 12' diameter."
(Lick Obs Bul, Vol 14, No. 420) gives the diameter as 6' and the class as 2 2 m.
by Jim Lucyk: Burnhams V2 p942, Observer's Guide (Astro Cards) 11-12/88 p33.
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
"cluster, coarse, unimportant."
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Journal BAA, 35, p159
S dense cluster of faint stars; about 6' diam.
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part II. M.N.R.A.S., 35(8), 280.
The RNGC (Sulentic and Tifft 1973) notes that this is a 10.0 mag open cluster.
Notes that this cluster is not large, being only 6' in diameter. Its 20 or so members gives it a total of 9th magnitude. In a 4-inch, the cluster appears as a fairly dim oval patch against a fine field of stars.
Described as "some 20 stars counted, intermediate rich, shows stars with some nebulosity surrounding. Very nice cluster. 6-inch, 48x."
Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "9M; 7' diameter; 50-plus 11M and dimmer members; looks very distant; this OPN CL straddles the ecliptic and is, at times, occulted by solar system bodies; 2 degrees ENE of PL NEB N2392."
Coe, observing with a 13" f/5.6, notes: "Bright, large, compressed. 30 stars counted at 100X. An unresolved backround of stars persisted even at 165X. A lovely curved chain of stars around the central clustering has the shaped of Corona Borealis, look for yourself."
:"This open cluster is about 10'x6', oriented north-south, with an arrowhead shape pointing to the east. I counted about 25 stars, with more stars hinted at due to its nebulous appearance. This object is fairly well detached, has a moderate range in stellar magnitudes, and is visible in the viewfinder."
6cm - broad 10' haze btwn two *s N&S. no res.
7cm - mod br, rich cl @ 30x, which shows hazy bkgrnd and sev *s. 50x: still hazy w/~15 *s easy to res + many more at threshold. circ, broad concen. brtst *s on W side of cl. BS, 15 Apr1993, Anderson Mesa.
15cm - mod br rich cl. 80x shows 15 brtr *s (m11-12) over unres haze 10' diam. un= pairs on W just outside core & off NW. 140x: 60 *s res incl threshold *s w/critically averted vis. grainy w/normal casual averted vis. brtr members give N-S elong, but underlying haze is circ. BS, 4Feb1991, Anderson Mesa.
25cm - mod br and compact. elong SE-NW, 6'x4'. at 180x about 20 *s res with a lot of unres haze which oocas sparkles through. perhaps 60 or more *s total.
30cm - 8'x6' in pa0. about 30 *s plus seven brtr ones (m11.5). brtst on W is m10.5
Alldays (22.50S, 20.12E, 770m).
12-inch f/10 SCT (76x, 218x)
This cluster appeared very rich with several stars packed into a rather small area. I have added this to my list for darker sky. The shape of Corona Australis or Beorialis in the middle section can be seen which is unique. Various magnitude faint stars.
Observing site: Little Tycho Observatory
[7h 38m 30s, 21° 34m 0s] I could make out 4 or 5 11th-12th mv stars, emmersed in a very faint cloud of dimmer ones.
Location:Blesfontein Guest Farm,Sutherland.
Sky Conditions:The most crystal clear sky possible.Dark moon and stars magnitude 6 and fainter are visible with the naked eye.Excellent clean sky,limited star flickering and brilliant objects.
This open cluster is fairly large which consists of 10th to 13th magnitude stars and that this cluster looks somewhat like a misty haze.The stars in this open cluster is well detached and that this cluster is strongly concentrated towardss each other.Most of the stars in this cluster are nearly the same brightness as each other.This open cluster measures 7.1'x5.4'.Chart No.213,NSOG Vol.1.
The Messier objects
The Bennett objects
The Caldwell list
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