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RA: 17h 47m 2.1s
Dec: −31° 30′ 0″
Ch: MSA:1416, U2:377, SA:22
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 21m
Mag: B=7.9, V=7.2
Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "Small cluster VIII class, 8' diameter, has 20 or 30 stars, 9..12m, nearly insulated."
Bailey, examining a Bruce plate (Harvard Annals, Vol 72, No 2), describes it as "Milky Way, coarse cluster, few stars, diameter 10'."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 10' and the class as 2 1 p.
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: "Pretty faint, pretty small, not compressed, 30 stars in an 8' field at 100X, not much.
10x50 tripod-mounted. 1997-07-06. Small blur just visible; no stars resolved [Rui Henriques]
Observing with a 6-inch f/8.6 Newtonian at 52x, it shows as a poor cluster of stars 10m and fainter. About 10-15 10th mag stars counted, no more seen at 108x. It has an irregular shape, apparently distributed into three clumpy regions. The same 10-15 stars are seen at 52x, making a delicate scattering of stars.
1997 July 9, Wednesday, 20:00 - 22:00 Jonkershoek. 11x80's tripod-mounted. Moderate conditions. A roundish puff of light, maybe a brighter patch near the centre. Like a low-surface-brightness globular cluster.
The Messier objects
The Bennett objects
The Caldwell list
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