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NGC 2158 (4,080 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




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NGC 2158

NGC 2158, Cl Collinder 81, Cl Melotte 40, C 0604+241, Ocl 468, VI 17, h 375, GC 1351

RA: 06h 07m 25s
Dec: +24° 05′ 48″

Con: Gemini
Ch: MSA:156, U2:136, SA:5

Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003), SEDS

(reference key)

Type: open cluster, 23r

Mag: B=9.49, V=8.6

Size: 5′
PA: ?


This small, compact open cluster, easily mistaken for a comet, lies on the South-Western edge of M35, and is smaller and much fainter than its famous neighbour. Although it shines with the light of a 8.6 magnitude star, its 40 or so component stars are fainter than 12th magnitude.

Historical observations

William Herschel (c.1784)

Synonyms: H VI-017

Discovered in 1785 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a very rich cluster of very compressed and eS stars, 4' or 5' diameter. A miniature of the 35 cluster of [Messier] which it precedes 1' 18 seconds and is 2' north."

Birr Castle/Lord Rosse

Observations with the 72-inch f/8.8 speculum telescope at Birr Castle noted "Jan 17, 1855. A pretty close cluster of small stars, followed by four or five bright stars."

Lassell, W. (1854)

Lassell, W. (1854) Observations of the nebula of Orion, made at Valletta, with the twenty-foot equatorial. Memoirs R.A.S., 23, 53-62.

Perhaps first unidentified object discussed on p.59?

Webb, T.W. (1893)

In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "about half a degree S.p., just beyond a group of outliers, is NGC 2158, a faint dim cloud of very minute stars."

Published comments

Trumpler, R.J. (1928)

(Lick Obs Bul, Vol 14, No. 420) gives the diameter as 4.5' and the class as 1 2 r.

Melotte, P.J. (1915)

A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.

Photo index

by Jim Lucyk: Deep Sky #2 Sp83 p31, Deep Sky #13 Wi85 p11, Deep Sky #6 Sp84 p25, Deep Sky Monthly 1/81 p14, Burnhams V2 p938, Messier Album p87, Sky&Tel. 3/60 p297.

Raab, S. (1922)

Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.

Discussed, based of F-A plates.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 12.0 mag globular cluster.

Modern observations

Ware, Donald J

:"Until I started pursuing my Herschel certificate, I never noticed this small cluster lying on the outskirts of M-35. It is about 3'x2', with about 10 stars superimposed on a nebulous patch of fainter, unresolved stars."

Callender, John

(e-mail: jbc@west.net, web: http://www.west.net/~jbc/)

Instrument: 8-inch Dobsonian reflector Location: Carpinteria, CA, USA

Light pollution: light Transparency: good Seeing: poor

Time: Sat Mar 1 05:00:00 1997 UT Obs. no.: 84

An obvious glow in the same 48X field as M35. Unresolved at low power; I'll come back to it with more magnification next time.

Walter Scott Houston

comments that "many amateurs do not notice this cluster, but in a 10-inch it sparkles with stardust." He notes that "in very good skies it seems to flirt with the edges of its monster neighbour [M35]. The brighter stars of NGC 2158 form a small arrowhead that is filled with fainter suns. It looks a bit like a comet..."

Hartung, E.J. (1968) Astron.Obj.South.Tel

Notes that "15cm is needed to show some of its stars. It is irregularly triangular, about 2.5' across and well resolved into numerous faint stars with a stream emerging sp. It is in effective contrast with a beautiful field of scattered stars on the sp edge of M35, and for small apertures looks somewhat nebulous."

Harrington, Phil

Harrington calls this a "gentle glow ... densely packed into a 5' area ... Through my 13.1-inch f/4.5 Newtonian the cluster appears as a multitude of dim specks dissolving into the warm glow of other, unseen suns."

Reeves, Ken

, in "SACNEWS On-line for February 1997", observing with a 10-inch f/4.5 scope, notes: NGC 2158 (06 07.5 +24 06) This open cluster is dwarfed in size by M 35 next door. This is a very distant and rich cluster and requires high power to resolve it. At 240X I saw about 18 stars over much haze with one very bright star at the east side. The overall shape of the cluster is triangular, pointing more or less to the south. After trying different powers, I decided that 170X was the best for that night, giving the best compromise between resolving stars and having the haze fade into the background.

Ancient City Astron.Club (1980)

described as "bright, fairly large, stands out well. No definite resolution seen, slight elongation, irregular shape. Located off southwestern edge of M35, vsible in same eyepiece field. 6-inch, 40x."

Steve Coe

Steve Coe, observing with a 13" f/5.6, notes: "Pretty bright, pretty small, very compressed, very rich, just barely resolved at 100X, going to 165X brings out more stars. I have seen this cluster with a wedge or arrowhead shape on a variety of nights using many different apertures. My best view of this cluster was in Richard and Helen Lines' 20" f/6 at 200X. The stars filled the field of view and it was difficult to tell where the cluster ended and the Milky Way began."

Brian Skiff

6cm - not res. found just S of a grp of ten way-outliers of M35. m10 * on SE


7cm - consp fuzz @ 30x in outlying area of M35. 75x: m10 * on NW consp, lies a

bit w/in border. just partially res w/a handful of *s. mod broad concen.

26Nov1992, Anderson Mesa.

15cm - at 38x looks like milky spot. 101x shows partial res w/10 or 20 *s,

loosely scattered. FtL.

- consp @ 80x as br partially res cl on SW periphery of M35. brtst *s

m13.0. 140x: m10.5-11 * on SE edge 2' from center. 4' diam w/40 *s res

plus much haze twd center. few outliers to S. extending SW is string of

m13 fld *s (same mag as brtst members). mod-broad or wk-even concen

across center. modhisfcbr. 25' from center of M35. BS, 4Feb1991,

Anderson Mesa.

20cm - 240x: five or six *s held. 6' diam. m10 * on E edge. milky haze, richer

twd cen. 20-30 *s about m12. circ except for glimpses of 1' arms to W

and S. SKJ, Pompano?

25cm - a milky spot at 45x. at 176x it is 3'-4' diam w/semi-globular appearance.

about 50 *s m13+. brtr from previous views.

30cm - part res w/12 *s vis. string of eight *s running NE-SW on W side. broad

concen w/core elong E-W. 4' diam. elong is elusive, poss due to brtr

core of cl being off-center to E. in moving fld, 6' diam.

Contemporary observations

Auke Slotegraaf


In a 2-inch refractor it is faint, appears roughly triangular using averted vision, with only a few stars occassionally sparkling out.

Magda Streicher

(no date)

Alldays (22.50S, 20.12E, 770m).

12-inch f/10 SCT (95x, 218x)

Situated on the SE boundaries of M35 it shows a tight knot of very faint stars, quite outstanding against the background. It makes a very lovely star field share with M35, which is much closer and brighter. Globular look. Brighter stars on the NE show the way to M 35, which show faint dark lanes with care. Will sketch this two next year.

Tom Bryant

2007-02-10 20:00:00

Observing site: Little Tycho Observatory

Telescope: C-8

[6h 7m 30s, 24 6m 0s] The companion cluster to M35 was a faint brightening of the sky. M35 itself was a faint brightening of the sky in the finder. Both were barely glimpsed in their respective telescopes.

2006-09-26 03:30:00

Observing site: Little Tycho Observatory

Telescope: C-8

[6h 7m 30s, 24 6m 0s] A very faint brightening of the sky near M 35. Only seen when the telescope was slewing.

Richard Ford

2013 February 6th, Wednesday

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.

Instrument:12-inch Dobsonian.

This open cluster looks like a milky glow which consists of 12th-13th magnitude stars and that this cluster is well detached.This open cluster has the strong resemblance of a globular cluster and that most of the stars in this cluster are nearly as bright as each other and that I have counted 40 stars within a fixed diameter in this cluster.This cluster measures 8.2'x 6.3'.Chart No.207,NSOG Vol.1.

Favourite lists

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The Messier objects

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