sponsored by psychohistorian.org
RA: 08h 00m 1s
Dec: −10° 46′ 12″
Ch: MSA:834, U2:275, SA:12
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 12r
Mag: B=8.28, V=7.6
Synonyms: H VI-037
Discovered in 1791 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a very compressed and very rich cluster of stars. The stars are of 2 sizes, some considerably large and the rest next to invisible. The compressed part 5' or 6' in diameter."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "Fine broad starry cloud, from 10th mag down to mere nebulosity; much better with 64x than higher powers. Vicinity gorgeous."
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part I. M.N.R.A.S., 35(5), 159.
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
Journal BAA, 35, p159
Almost of the globular class; mostly very faint stars; 16' diameter.
Photo Index by Jim Lucyk: Sky&Tel. 8/81 p115, Burnhams V2 p1214.
The RNGC (Sulentic and Tifft 1973) notes that this is a 8.5 mag open cluster.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 11' and the class as 1 2 r.
Listed by the Herschel Club, described as "some 50 stars, considerably rich and concentrated, nebulosity visible, very beautiful cluster, mag of stars constant overall. 6-inch, 48x."
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "8M; 10' diameter; large, rich and condensed; 75-plus 11M and dimmer members."
Steve Coe, observing with a 13" f/5.6, notes: "is bright, pretty large, compressed and rich at 100X. It has about 40 members that are obvious and a hazy backround, even at higher powers."
Location: Pietersburg (South 23 53. East 29 28).
Sky conditions: Good.
Instrument: Meade 12 inch (Eyepiece 40mm).
Date: 25 January 1998.
Field of view: 52.7 arc minutes.
Large, but smaller and fainter than 2489. Irregular, fairly compressed with bright and faint stars with some haziness visible. Busy starfield.
12-inch f/10 SCT (EP: 2-inch 40mm SW 76x 53' fov; 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov; 2-inch 8.8mm UW 346x 15' fov)
Rich cluster, slightly irregular and fairly compressed. Haze can be distinguished in and around the cluster. A dark section can be seen towards the southern section. A beautiful misty cluster, in the dark of night. A nineteenth century textbook describes it as follows: "fine, broad starry cloud from 10th magnitude down to mere nebulosity much better with higher powers. Rich cluster, slightly irregular and fairly compressed. Haze can be distinguished in and around the cluster. A dark section can be seen towards the southern section. A beautiful misty cluster, in the dark of night. This splash of various magnitude stars seems to share a crouded space although resolved. Haze is obvious part of the cluster. Lovely composition of faint stars which is a typical cluster feeling. The NE is not so busy and darker areas can be seen between the stars towards the NW. (Mag 7.6; size 6.0'; number of stars = 150. )
Observing site: Little Tycho Observatory
[8h 0m 12s, -10° 47' 0"] A group of 3 12mv stars in an equilateral triangle. The cluster appears to be slightly to the west of it's marked position by 1'. Confirmed, WikiSky.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
The stars in this open cluster is well detached and that this cluster looks almost compact.In this cluster the stars are nearly the same brightness as each other and that there is a bright chain of stars seen together in this open cluster.To note NGC 2506 consists of 80 stars arranged in a tight area consisting of 11th to 12th magnitude stars.This open cluster measures 52.7'x 40'.Chart No:257,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.