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RA: 05h 31m 26.6s
Dec: +34° 14′ 58″
Ch: MSA:113, U2:97, SA:5
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 13pn
Mag: B=?, V=10.1
Synonyms: H I-261
Discovered in 1793 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "vB, iR, vgbM, 5' diameter. Seems to have 1 or 2 stars in the middle, or an irregular nucleus; the chevelure diminishes very gradually."
In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "Haze surrounding 4 minute stars, 9.3-inch speculum. William Herschel, 3 only in 3 obs., d'Arrest 5; E. of Rosse 6, oval with branches."
Publ.Lick.Obs. Volume 2."Observations of Nebulae with the 36-inch Refractor of the Lick Observatory", p 168.
This is one of the discoveries of Herschel I. It has been drawn by Herschel II and by d;Arrest. Herschel in his observations of nebulae, descrbies it as 'a nebula incuding a triple star, forming an equilateral triangle; sides 4'', stars = 11, 12, 14m." The truple was entered as No 367 of his 'Second Catalgoue of Double Stars' with the folllowing note: "One of the most curious objects in the heavents. It is a triple star forming an equilateral triangle, and placed exactly in the center of a small circular nebula which extends a litttle beyond the stars." No measures were made, but the distance was estimated as 7''.
In 1876 I looked at this with the 6-inch and found the nebula faint with that aperture but the three stars were easily seen. With the 18.5-inch in 1878 I noted several other stars in the group, just outside of the nebula. The 36-inch telescope now shows that one of the stars of the triangle is double, having an exceedingly faint attendant at a distance of a little more than 2''. This is a difficult pair under ordinary cnditions with this telescope, and probably could not be seen at all in any other telescope with hich this object has been observed."
Measures of the star positions are included.
Ced 49 (NGC 1931)
Position (1900): RA 5 24.8, Dec + 34 10
Star: Cl (Mp=9.7:)
Spectrum of nebula: (not classified)
Classification: Nebulous cluster (Nebulous envelop of intricate structure, eg. NGC 2175)
Notes: "NGC 1931 = GC 1137 = h 355 = H I 261. Disc. 1793. FA 145. WP 66. (114, 153, 194, 208, 216, 252, 354, 549, 578, 630 Pl 32, 631, 632, 796)."
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.
Lynds, B.T. (1962) Catalogue of dark nebulae. Astrophys.J.Suppl.Ser. 7, 1-52. [also: computer datafile: VII/7A]
(Sulentic and Tifft 1973) notes that this is a 13.0 mag cluster associated with nebulosity.
Photo Index by Jim Lucyk: Deep Sky #13 Wi85 p8, Vehrenberg's Atlas of DS Splendors (3ed) p59, Vehrenberg's Atlas of Galactic Neb-1 p59.
Hartung notes that "this curious object . . appears as a bright round nebulous haze about 1' across with indefinite edges; near the centre is a close triplet, the northwest star much the faintest, which 15cm will show."
Listed by the Herschel Club, described as "mag estimated as 9.5, diffuse nebula, star-like in appearance with nebulosity surrounding it. 8-inch, 96x."
This nebula lies almost 1 degree east-southeast of Phi Aurigae. It is a tiny but rather bright emission and reflection nebula surrounding a 9th magnitude star. The star is quite obviously fuzzy in a 6", and shows well through light pollution. The star itself is triple (mags 9,10 & 11) and is designated ADS 4112. The nebula could possibly be part of the great Aurigae OB1 association of young stars.
Burnham calls it bright, large and round, 3' across, with several stars involved.
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "12M; 3' diameter; two or three 13M stars superimposed or embedded in this combined reflection/emission nebula."
05 31.4 +34 15
17.5: five stars (three brighter stars) located within a bright, small
nebulosity of high surface brightness. A sixth very faint star is just
outside the nebula. Dims with OIII filter so must have a predominant
13: five stars involved including three close fairly bright stars. A fourth
very faint star to the W, fifth very faint star NE and sixth extremely
faint star W. Bright, high surface brightness nebulosity.
8: compact, striking nebulosity involving several stars.
15cm - three *s seen w/neb @ 165x.
- sm fairly br neb w/m10.5 * @ 50x. 140x/195x: elong NE-SW, 3'x1'.5,
reaching halfway to m12 * SW. 195x shows four *s in trapezium (NEmost
comp vf) and two other vf *s in neb SW. no filters helpful: DS does no
harm, [OIII] kills it ---> reflection neb. BS, 4Dec1989, Anderson Mesa.
25cm - 1'.5x1' w/m10 cen * and three comps. the two fntr *s are m12.5 and 13.
smooth and w/o features, elong NE-SW. BS, Roof.
- 1'.5x1' in pa45. needs more than 190x. tapered twd SW end. brtst * m11,
four others. to S & SE is poss assoc cl. BS, 6Oct1981, Anderson Mesa.
30cm - easily seen @ 149x as a neb around * on NW side of a 4' on-a-side box.
238x: elong pa45, 1'.5x0'.75. with careful scrutiny, there can be seen
four *s in a tight *ism w/brtst on E. sketch in notes. CBL, Roof.
16-inch f/10 SCT (290x)
Another interesting open cluster, with a few very stars embedded in haziness. At 102x it looks like a galaxy. The stars gather more south in the nebula.
Observing site: Little Tycho Observatory
[5h 31m 24s, 34° 15m 0s] This appears to be a faint (11mv) double surrounded by nebulosity. Confirmed, Burnam, WikiSky.
The Messier objects
The Bennett objects
The Caldwell list
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