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RA: 17h 40m 12s
Dec: −36° 57′ 0″
Ch: MSA:1438, U2:377, SA:22
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 22m
Mag: B=?, V=8.8
James Dunlop discovered this object from Paramatta, New South Wales, and included it as No. 568 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a very faint cluster of very small stars, resembling faint nebula; the stars are considerably congregated to the centre, irregular round figure."
Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "Cluster class VII, p rich; pL, irr R, 8', stars 9..10m."
The NGC records it as "pretty large, pretty rich, irregularly round, stars between 9 and 10th magnitude."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 7.5' and the class as 1 2 p.
The clusters 60 or so stars are spread over a 7' area, and according to Trumpler it is detached from the background, exhibits weak concentration towards the centre, and has a moderate brightness range.
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.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.0 mag open cluster.
Steve Coe, observing with a 17.5" f/4.5 at 100X, notes: "Faint, pretty large, somewhat rich at 100X. This is a long string of stars with several other members.
1997 March 15. Jonkershoek. 11x80 tripod mounted. No moon. Elongated fuzzy glow, east of the sting. Looks like an elongated globualr cluster. Readily seen.
A 15.5-inch telescope working at 220x shows it as a small open cluster of highly irregular shape lying to the north of an 8th magnitude star. The grouping is very irregular, the pretty bright stars allowing the eye to form many trails and curls; there are at least three star chains and one star loop easily visible. There are roughly two dozen 10th magnitude stars here. The cluster appears roughly elongated in a north-south direction.
1997 July 9, Wednesday, 20:00 - 22:00 Jonkershoek. 11x80's tripod-mounted. Moderate conditions. Milky way haze, no stars. Clearly elongated north-south -- just like an oval globular cluster.
The Messier objects
The Bennett objects
The Caldwell list
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