sponsored by psychohistorian.org
RA: 06h 15m 9s
Dec: −18° 38′ 36″
Con: Canis Major
Ch: MSA:324, U2:317, SA:19
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 22r
Mag: B=9.35, V=8.6
Discovered by Caroline Herschel. William Herschel (1786) noted she used "an excellent small Newtonian Sweeper of 27 inches focal length, and a power of 30.".
Synonyms: H VII-013
Recorded in 1785 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a cluster of scattered stars, not very rich, above 15' diameter."
Burnham calls this a large, pretty rich open cluster, 10' diameter with about 20 faint stars.
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 9' and the class as 1 2 m.
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 9.5 mag open cluster.
Listed by the Herschel Club, described as "scattered, yellow-orange star visible within cluster. 8-inch, 48x."
AJ Crayon, using an 8" f/6 Newtonian, notes: "is an open cluster, is 10m 10' has 20 stars of 8m and 12m to the 14m limit of the telescope at 100x. Averted vison does not help, you must be dark adapted!
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "9M; 10' diameter; 60-plus 12M and dimmer members; fairly rich, though dim and poorly resolved; 6M star off NW edge is SAO 151274; 100' WSW of Mirzam (Beta CMA)."
Steve Coe, using a 17.5" f/4.5, notes: "Bright, pretty large, compressed, rich, 54 stars counted in the 13" f/5.6 at 220X. Several nice chains of stars with a backround of fainter members, easily seen at 100X. Years earlier I saw a "K" shape, 30 stars and a somewhat milky backround of stars with one orange 9th mag * to one side using the 17.5" at 100X."
25cm - vf. 20' diam elong E-W. 20 *s res w/much irresolved haze.
30cm - 140x: loose, barely distinguishable. 35 *s fntr than m12.5 in an irreg-
outlined 13' diam. enclosed in an E-pointing kite-shaped box 18' long.
one long string. w/o haze.
A 10-inch f/5 at 30x shows this as a very faint, elongated milky patch of light lying inside a triangle of 9th mag stars; undecided whether it can be resolved, but there does appear to be a line of four or five slightly brighter stars in the general haze. At 120x this line of stars is shown to be only two stars, and a further two, even fainter stars, can be glimpsed.
Observing site: Little Tycho Observatory
[6h 15m 42s, -18° 39' 0"] An 11mv star surrounded by a faint glow.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
This open cluster is well detached which consists of 12th to 13th magnitude stars which has an irregular appearance which this cluster takes the form of a X-shaped pattern.Most of the stars in this cluster is nearly as bright as each other and that this clusters stars are not at all concentrated.At both 57x and 75x this cluster looks like a hazy pattern of faint unresolved stars.This open cluster measures 7.1'x 3.5'.Challenge Rating:Moderately Easy.Chart:No.89,NSOG Vol.1
The Messier objects
The Bennett objects
The Caldwell list
DOCdb is still in beta-release.
Known issues, feature requests, and updates on bug fixes, are here:
Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!
DOCdb is a free online resource that exists to promote deep sky observing.
You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.
Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.