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RA: 07h 18m 36s
Dec: −24° 59′ 0″
Con: Canis Major
Ch: MSA:345, U2:319, SA:19
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 13r
Mag: B=?, V=4.1
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This beautiful and interesting cluster, also known as Collinder 136, lies around the bright star 30 (Tau) CMa. Trumpler classified it as detached from the stellar background, strongly concentrated towards the centre with a large range in stellar brightness. About 60 stars are packed into a 8' area, the brightest star being of 8th magnitude. The combined mass shines at 4th magnitude, but cannot be seen with the naked eye because 30 CMa drowns out any light from the cluster.
NGC 2362 is 5400 light years from Earth. Tau CMa at V=4.40 has an absolute visual magitude of -6.7 making it one of the intrisnically brightest stars. All of the stars visible in amateur telescopes in this cluster are much brighter than our Sun. At that distance, our Sun would have a visual magnitude of only 15.9!
Synonyms: H VII-017
Discovered in 1785 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a very beautiful cluster of pretty large stars, very rich. Contains the 30 Canis."
Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "a fine cluster of discrete stars, 60 or 70 in number. R, gbM, 8' diameter."
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 7' and the class as 1 3 p.
Burnham calls it as "unusually attractive and interesting cluster of stars surrounding the 4th magnitude Tau or 30 CMa ... In very small telescopes the object may at first present the appearance of a nebulosity about the star, but any good 2-inch telescope should resolve it easily into a rich little cluster of some 40 stars. The apparent diameter is about 6' and the magnitudes of the members range from 7.5 to about 13.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Sanford calls it a "beautiful cluster of several dozen stars gathered around 4th magnitude Tau, which is a wonderful triple star. Although rather low for some northern observers, this cluster is a neglected showpiece of the skies."
Photo Index by Jim Lucyk: Sky&Tel. 9/60 p141, Sky&Tel. 2/78 p189, Sky&Tel. 8/73 p79, Astronomy mag. 2/88 p90, Burnhams V1 p444, Vehrenberg's Atlas of Galactic Neb-1 p118.
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
The RNGC (Sulentic and Tifft 1973) notes that this is a 4.0 mag open cluster.
Hartung notes: "This most beautiful cluster contains about forty stars grouped around the very bright white 30 CMa which is set like a jewel in their midst. Near it are two companions (10.0, 8 arcsec, pa 90 deg; 11.2, 14 arcsec, 78 deg) forming an elegant triplet, both of which 7.5cm will show with close attention. The cluster is irregularly round and makes a charming telescopic object."
Listed by the Herschel Club, described as "a very pretty cluster, resembles a temple, look closely, some 40 stars counted, large and bright star in centre. 6-inch, 48x."
Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "4M; 6' extent; 50-plus 5M and dimmer members; STRIKING! center blue star = 4M Tau CMA; 1 degree to SW is OPN CL N2354."
Donald J. Ware:"A small but very pretty open cluster surrounding the star Tau CMa. It is about 6' in diameter, compact, and well concentrated. I counted about 40 stars with most of them being moderate in brightness."
AJ Crayon, using an 8" f/6 Newtonian, notes: "is a bright open cluster around the star tau. In the 8x50 finder, only tau is visible. At 120X it appears 9m 10' and has 3 ranges of stellar magnitudes; tau, 10 and 12.
Steve Coe, using a 17.5" f/4.5, notes: "pretty bright, pretty large, somewhat compressed, round at 165X. Tau CMA and about 45 stars. Tau has dark band around it, then cluster members. Tau has two companions that form almost a straight line. Tau is white, the two comes are bluish and both are on one side of Tau. Having a bright triple star in the center of a cluster is quite unique and I return to this object often. "
6cm - 15 *s w/haze around tau CMa, which interferes.
15cm - tau CMa surrounded by a doz m10 *s in 5' diam. f *s seem quite bluish.
BS, 1Nov1970, FtL.
25cm - vinteresting & br. vbr central * w/blue covey surrounding it. main * has
two m11 comps. triangular form; hix fine.
30cm - beautiful. 50 *s roughly triangular group pointing S around tau CMa.
evenly [uniformly] spread, mostly m10.5. some close grps; tau eccentric
to N side.
Date: 2006 12 23, 21:00
Instrument: 8-inch Dobsonian, 25mm eyepiece
Sky: Clear; light pollution
Notes: Small open cluster. Could only count about 12 stars. Very bright star in the middle surrounded by semi-circle of faint stars.
Date and Time: 18 May 2009, 20:00
Location: Prince Albert (Western Cape, South Africa).
Instrument: Skywatcher 90mm (3.5") f/10 Achro Refractor
Eyepieces: 10mm (91x, 34′ FOV), 25mm (36x, 1.4° FOV)
Sky Conditions: Seeing: 5/10. Transparency: Average
36x: Small open cluster roughly 10′ in size surrounding a bright 4th magnitude star. Stars are of mixed brightness with the bright central star, 3 slightly fainter stars and roughly 13 faint stars visible using averted vision. At low magnification it is difficult to easily resolve most of the stars.
91x: Stars are much better resolved. Approximately 27 can be easily counted. The cluster appears to have a rough triangular shape with corners to E, NW and SW. Stars are concentrated towards the center of the cluster.
In hand-held 7x50 binoculars, the cluster is quite challenging, but a two-inch refractor gives a most pleasant and surprising view. If you look directly at Tau, you only see it and two or so other stars, but with the slightest averted vision, the bright cluster jumps into view as a sparkling mass, with Tau offset from the middle. Hartung says Tau is "set like a jewel" in the midst of the cluster, which is "irregularly round and makes a charming telescopic object."
With a 15.5-inch the cluster appears angular to the east and somewhat irregular on its western border. It is dominated by the bright Tau, which has two stars lying close by to the east. The eastern most star has a reddish hue. Hartung notes that the one is of mag. 10.0, 8 arc second away in PA 90 , whilst the other companion shines at magnitude 11.2, 14" away in PA 78.
10-inch f/5 at 30x shows this really interesting object; if you stare directly at Tau, you see about 12 stars arranged in a rectangular shape; the slightest averted vision and the empty black space between these stars suddenly fills in with fainter members. Overall the cluster forms a roughly triangular grouping.
Sutherland (Ouberg Quarry)
11x80 tripod mounted binoculars
Conditions: NELM: fainter than 6.0 at the S.pole
Single, very bright, star; averted vision shows hard-to-see glow of very very faint stars closely surrounding it. Not at all obvious in binoculars. Used Uranometria chart 319 to locate it.
Telescope: Meade 8" - 18mm wide angle eyepiece.
Beautiful, irregular-triangle shaped cluster, with bright compact stars around Tau Canis Major. About 20 stars: some of them grouped more to the west. To the east a fairly bright star just outside the rims of this pretty cluster with fainter stars are scattered with some haziness in between. Large cluster about 8 arc minutes in size.
Instrument:12-inch Dobsonian Reflector Telescope.
Eyepieces:26mm Super Wide Field Eyepiece.
20mm Ultra Wide Angle Eyepiece.
Sky Condtions:Dark moon and stars magnitude 6 and fainter are barely visible with the naked eye.
Transparency of the Sky:The most clear sky possible.
Seeing:Excellent clean sky,limited star flickering and brilliant objects.
Object Type:Open Cluster.
First Impression:This object looks like an open cluster.
Chart Number:No.15(Extract taken out of "Atlas of the Night Sky").
Size:26mm Eyepiece:Field Of View:57'/6=9.5'.
20mm Eyepiece:Field Of View:50'/5.5=9.0'.
Size in Arc Minutes:9.2'.
Open Cluster is 9.2'*4.6'.
Brightness Profile:From the far outskirts this cluster is evenly bright all over.
Challenge Rating:Stunning Sight.
This open cluster's are well detached.In overall I have counted 30 stars.There are bright and faint stars mixed together.The stars in this open cluster are strongly concentrated towards each other.By observing this cluster this cluster has a slight oval shape of bright stars arranged in a circle.
Observing site: Pinnacles overlook
[7h 18m 48s, -24� 57' 0"] A lovely grouping of around 20 bright (10 mv or brighter), blue, stars with a 7th mv star in the center.
Location: Bonnievale SSP (Night Sky Caravan Park)
Binoculars: Canon 12x36 IS (5-deg fov)
Sky conditions: Good (8/10)
Quality of observation: Good
NGC 2362 Open cluster with bright central star and almost triangular south-west to north-west. Dimmer stars around it. Pretty.
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