37 Cluster

Image gallery

Historical observations

William Herschel (c.1784)

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."

Published comments

Trumpler, R.J. (1928)

Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 6' and the class as 2 3 p.

Doig, P. (1925)

Journal BAA, 35, Sep, p316.

Double star in small cluster.

Bailey, S.I. (1913)

Bailey, examining a Bruce plate (Harvard Annals, Vol 72, No 2), describes it as "coarse irregular cluster, about 20 pretty bright stars, diameter 5'."

Photo index

by Jim Lucyk: Vehrenberg's Atlas of Galactic Neb-1 p88 (on photo with Sh 2-268).

Vorontsov-Velyaminov, B. (1925/1926)

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.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 7.0 mag open cluster.

Modern observations

Walter Scott Houston

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."

Ancient City Astron.Club (1980)

Listed by the Herschel Club, described as "15 stars visible, bright and tightly grouped. 8-inch, 48x."

Tom Lorenzin

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."

Gramer, Lew (IAAC)

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!

Walter Scott Houston (1975)

See: Houston, W.S. (1975) Four neglected deep-sky wonders. Sky&Telescope, Dec, 420.

Steve Coe

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."

Pensack, Don (n.d.)

Alan,

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.

Don Pensack

Contemporary observations

Auke Slotegraaf

2012 February 18, Saturday

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.

1982

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

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.

Richard Ford

2011 January 8th, Saturday

Location:Perdeberg.

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.

Limiting Magnitude:4.9.

1.NGC 2169

1.1.Object Type:Open Cluster.

1.2.First Impression:This object looks like an open cluster.

1.3.Location:Orion.

1.4.Time:9:25pm.

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'.

5.7'/5.5'=11.2'.

11.2'/2=5.6'.

Size in Arc Minutes:5.6'.

1.7.Brightness:Magnitude 5.9.

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.

1.10.Description

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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

slightly concentrated.

Tom Bryant

2008-02-14 19:00:00

Observing site: Little Tycho Observatory

Telescope: C-8

[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.

2008-02-02 21:00:00

Observing site: Little Tycho Observatory

Telescope: C-8

[6h 8m 24s, 13° 57m 0s] A bright, loose cluster of around 16 stars. 4' x 6' in position angle approximately 135°.