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RA: 07h 02m 48s
Dec: −08° 22′ 36″
Ch: MSA:273, U2:273, SA:12
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 23r
Mag: B=6.27, V=5.9
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In the Appendix to the 1912 'Scientific Papers of Sir William Herschel' this object is described as "1785, March 4, a very brilliant cluster of large stars, considerably compressed and rich, above 20' in diameter, the stars of various sizes, visible in the finder."
Observations with the 72-inch f/8.8 speculum telescope at Birr Castle noted "Feb 13, 1852. Coarse cluster."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 16' and the class as 1 2 m.
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part II. M.N.R.A.S., 35(8), 280.
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
"A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.
"irreg., condensed; fairly bright stars." He gives the approx. diameter as 19 arcmin.
The RNGC (Sulentic and Tifft 1973) notes that this is a 7.0 mag open cluster.
Harrington calls this a "magnificent but highly overlooked cluster, the only Messier object in Monoceros ... the cluster measures about 16' across and contains 80 stars. Some two dozen reveal themselves in small telescopes, while an 8-inch instrument quadruples the count. Most of them shine with the characteristic blue-white hue of young stars, though a lone ruddy beacon punctuates the cluster's centre."
Steve Coe, observing with a 13" f/5.6, notes: "(M 50) is bright, large, round, somewhat compressed and pretty rich at 100X. It is easy in the finder and I estimated 100 members or so. There are several nice chains of stars with an orange one on the SE edge."
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "6M; 20'x 10' extent; 100-plus members; WNW-ESE extension appears to thin out into a star-poor patch just S of center; OPN CL N2335 1.8 degrees to SSE at the N-most end of I.2177; OPN CL N2343 and N2353 in same general area; see VADSS-81."
Danie Cronje, observing with 10x50 binoculars, calls it "quite large, bright. Contains 2 brighter stars at first glance. (1) actually a pair with a faint star (2) tip of a thin triangle. There also seems to be a slightly fainter star in the centre. The rest of the cluster is the glow of faint stars - a few can be resolved."
A 10-inch f/5 shows this to be an attractive grouping of 9th mag and fainter stars. At 30x one notices a single reddish star amidst the whites of the other brighter members and the pale gray of the many fainter stars. This irregular grouping presents the eye with many streamers of stars. At 100x the cluster overflows the filed, and the irresolved haze now clearly shows many small stars, making for a rich grouping of a few bright and very many fainter stars; an attractive if somewhat dim sight.
Alldays (22.50S, 20.12E, 770m).
12-inch f/10 SCT (76x, 218x)
Displays an eagle in flight, or perhaps a kite. Very elongated NW – SE, with the bulk of the stars towards the NE which gives it then a more round shape. In a way it resembles M6 the Butterfly cluster. My sketch show this cluster well. Bug cluster with head "voelers" extended about 10' to the N and S. The rest of the faint stars spray out from this middle part towards the west in a round figure almost 12'x9' in size more or less. Just slightly mingle with the field stars.
Observing site: Pinnacles overlook
[7h 3m 12s, -8° 20' 0"] A large (15-20 arc minute), loose cluster of star chains. Whether this effect was due to actual stellar formations as chains or an illusion of my visual processing is unknown. The cluster is in a very rich region of the milky way. A splendid wide field view.
Instrument:12-Inch Dobsonian Reflector Telescope.
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.
This open cluster is well detached which consists of young stars in the magnitude range of 4th to 7th magnitude stars.This open clusters are nearly the same brightness as each other which sparkle almost like diamonds under a black velvet sky. The stars in the center of this cluster grows brighter compared to the stars in the far outskirts of this cluster.
It measures 19.5'*6.5'.
Challenge Rating:Very Easy.
Observer: Carol Botha
Location: Betty’s Bay
Instrument: 12 inch Dobsonian F5. Binoculars 10x50. Eyepiece: 25mm plossl (fov 50')
Sky: Clear. Some light pollution E horison
Limiting mag: 5.55 HD59256
Quality: Very windy. Observing with shade netting shelter
Dimension: 16.0' x 16.0' (Cartes du Ciel)
Open cluster in Monoceros.
Binoculars: Even though the brightest stars of Monoceros are very faint to the naked eye, the constellation shows a stunningly rich star field through binoculars. Locating the cluster was easy. Starting at Sirius and scanning the sky NNE towards Procyon I saw a somewhat fuzzy patch.
25mm: Bright and faint stars form the heart shaped outline with the brightest – a yellowish-orange star S. Within the 'heart' lies a nebulous region which seems to be brighter towards NW. I can almost hear this heart beating! The 'heart' is framed by pairs of bright and medium bright stars N, W, S, and E
The Messier objects
The Bennett objects
The Caldwell list
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