sponsored by psychohistorian.org
RA: 06h 08m 32.5s
Dec: +13° 57′ 57″
Ch: MSA:204, U2:182, SA:11
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 33m
Mag: B=5.99, V=5.9
Select a sketch and click the button to view
Synonyms: H VIII-024
Discovered in 1785 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a small cluster of pretty large white stars."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 6' and the class as 2 3 p.
Journal BAA, 35, Sep, p316.
Double star in small cluster.
Bailey, examining a Bruce plate (Harvard Annals, Vol 72, No 2), describes it as "coarse irregular cluster, about 20 pretty bright stars, diameter 5'."
by Jim Lucyk: Vehrenberg's Atlas of Galactic Neb-1 p88 (on photo with Sh 2-268).
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 6.37.
The RNGC (Sulentic and Tifft 1973) notes that this is a 7.0 mag open cluster.
The brightest member is the seventh magnitude multiple star Struve 848. Houston notes that "the next three brightest components of this system are of mag 9, and lie 2.5" east, 28" east and 43" south of the primary."
Listed by the Herschel Club, described as "15 stars visible, bright and tightly grouped. 8-inch, 48x."
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7M; 4' extent; sparse! count seventeen 7 thru 9M stars in two parts, larger to E; midway and SW of a line between Xi ORI and Nu ORI."
Observer: Lew Gramer; Your skills: Intermediate; Date/UT of Observation: 1998-02-19/20 03:40 UT; Location: Backyard, Medford, MA (Lat 42oN); Site classification: Suburban; Limiting magnitude: 5.6; Seeing: 7 (1-10, 10 best); Moon up: no; Instrument: 7x50 handheld binoculars; Magnification: 7x; Filters used: none; Object: NGC 2169
An easy *tight* group which forms the S vertex of a triangle with the two "club" stars (xi and nu) in Orion. (Note that this trio, including the club stars and the cluster, are easily mistaken in the binocs for nearby 134 and 133 Tauri to the NW, and the little clump of stars around HD 39880!) The OC is connected with xi and nu Ori by faint streamers of resolved and unresolved stars. One pretty pair of mag. 6 stars to the E points directly at the direct vision "haze" of NGC 2169. Within this "haze", a steady hand will show at least 3 or 4 "concentrations" or stars embedded. These clumps all appear to be stellar mag. 5 or 6. Pretty!
See: Houston, W.S. (1975) Four neglected deep-sky wonders. Sky&Telescope, Dec, 420.
Steve Coe, using a 13" f/5.6, notes: " Pretty bright, not compressed open cluster in the 17.5 inch at 100X. What is bizarre is that the cluster members form the numerals "3" and "7". It is a shame that this is not M-37, you couldn't miss it."
I see NGC 2169 as Sigma Nu, not 37. My wife calls it the Sorority Cluster. Look at it again and see if you see the Greek letters.
Location: Paardeberg (ASSA Cape Centre dark sky site)[33:34.4S, 18:51.3E]
Time: 23:10 SAST
Binocs: 15x70 Celestron
A very bright, small knot of five or so stars, in angular arrangement.
In a 2-inch refractor, this multiple star forms the apex of a bright isoceles triangle, which dominates the grouping, obscuring any fainter stars.
1984 December 30 23:12-23:22. PRG, 15.5-inch f/9 Newtonian, 220x.
In a 15.5-inch reflector at 220x it appears as a smallish loose open cluster, with few stars. Most of the stars are bright, and there are no very faint stars. The open cluster is wide (spread out) and appears divided into two parts. There is one very bright star, 4 somewhat fainter stars and the other stars much fainter. It is very easily visible in the finderscope.
Instrument:12-inch Dobsonian Reflector Telescope.
Eyepieces:26mm Super Wide Field Eyepiece.
20mm Ultra Wide Angle Eyepiece.
Sky Conditions:The fainter parts of the Milky Way are barely visible.
Transparency of the Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
1.1.Object Type:Open Cluster.
1.2.First Impression:This object looks like an open cluster.
1.5.Chart Number:No.26(Extract taken out of "Herschel 400 Observing Guide").
1.6.Size:26mm Eyepiece:Field Of View:57'/10=5.7'.
20mm Eyepiece:Field Of View:50'/9=5.5'.
Size in Arc Minutes:5.6'.
1.8.Brightness Profile:From the far outskirts of this open cluster it is evenly bright.It grows brighter towards the centre of this cluster.
1.9.Challenge Rating:Very Easy.
This open cluster is very small when I first observed
it.By observing this open cluster it looks exactly
like the number 37.The stars in this open cluster are
nearly the same brightness as each other and they are
Observing site: Little Tycho Observatory
[6h 8m 24s, 13° 57m 0s] A cluster of 10 bright stars (brighter than 10mv), surrounded by about 10 more faint ones (fainter than 11 mv) in the form of an equilateral triangle around 15 arc minutes in size. The triangle is truncated on its southwestern point. The double Struve 848 is close to the center of the cluster.
Observing site: Little Tycho Observatory
[6h 8m 24s, 13° 57m 0s] A bright, loose cluster of around 16 stars. 4' x 6' in position angle approximately 135°.
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.