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RA: 16h 32m 42s
Dec: −52° 38′ 0″
Ch: MSA:1497, U2:433, SA:26
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 33r
Mag: B=?, V=8.1
Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "a large and coarse milky way cluster, tolerably insulted, composed of large stars."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 20' and the class as 1 2 m.
"Cat. of Open Cl. south of -45° Decl.", Mem. 17 Mnt Stromlo Obs.
The RNGC (Sulentic and Tifft 1973) notes that this is a 8.0 mag open cluster.
15cm - 25' diam broadly concen protrusion from Norma *cloud W to dk area E. sm 1'.5 clump of ten *s nr center. about 100 *s total, m10.5+. BS, 27Feb1990, LCO.
10x50 tripod-mounted, 1997-05-02 (clear skies, no light pollution on horizon, dew on binocs): very dim, about 15' wide, 5 members were resolved [RH]
Location: Night Sky Caravan Park, Bonnievale.
Date: 2016 Oct 30, Sunday.
Time: 21:20 SAST
Telescope: Little Martin (4-inch f/6.5 Celestron refractor)
19mm Panoptic (35x): An obvious but gentle object. Vast dim cluster on a superbly rich field of bright stars. The bright field stars seem sprinkled casually over this large grouping of moderately faint stars. Three of them make a 90° triangle containing the cluster. How many stars in the cluster? Dunno - 40?
Observing with a 6-inch f/8.6 Newtonian on 24/05/93 at 43x. The large field is delicately sprinkled with small stars. Roughly in the middle of the cluster are two small knots of stars, clearly separated by a starless gap. The two knots lie oriented north-south. At 52x, the northern one appears triangular and the southern one, which is more prominent, appears elongated. At higher powers, the northern knot consists of four 10th mag stars in an irregular trapezium. The southern knot is triangular, and at its southern tip lies a double stars -- a total of 5 stars make up this triangle. Viewing at 144x doesn't show many more stars, and at this power you are looking right through the cluster, and the star-less voids are numerous. Stars seen to about 11th mag, and I guess there are overall 50 stars in the cluster, with 20 or so 9-10th mag stars. I estimate the Trumpler class as II 2 R-VR. On the western edge of the cluster is a fine, very unequal double star; the primary has a very distinct orange-red colour.
1994-03-15 Die Boord, 6-inch f/8.6 Newtonian. At 52x, the 40' field appears as a patchy star field, too scattered to impress. Well bounded by stars.
This open cluster is not at all definite in 11x80 binoculars. It looks like a very slight brightening of the night sky, or a very faint part of the Milky Way.
1997 April 05, 01:00 SAST, Coetzenburg, 11x80 tripod-mounted binoculars. Irregular glow, looks like dense starfield only. About 1 degree north is a brigher, more coarse version.
The Messier objects
The Bennett objects
The Caldwell list
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