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RA: 16h 49m 28s
Dec: −53° 43′ 42″
Ch: MSA:1497, U2:433, SA:26
Ref: SIMBAD, DAML02, Archinal&Hynes (2003)
Type: open cluster, 32r
Mag: B=8.06, V=7.2
James Dunlop discovered it from Paramatta, New South Wales, and included it as No. 364 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "A round, faint nebula, about 1' diameter, with three small stars in it; a bright star south of the nebula."
Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "A pretty insulated milky way cluster, class VII of large stars; 8' diameter; stars 9..12th magnitude." His second observation records it as "cluster class VII; rich; not much compressed in the middle; more than fills field; stars 11.14th mag but chiefly small."
"Cat. of Open Cl. south of -45° Decl.", Mem. 17 Mnt Stromlo Obs.
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 20' and the class as 4 2 mU.
Burnham calls it large, rich with a 20' diameter.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.0 mag open cluster.
Phil Harrington (1990, Touring the Universe through Binoculars) calls it an "attractive little open cluster found north of Zeta Areae. Here, observers will find a small 7th mag glow representing about 60 cluster stars. The brightest of these shine at 9th magnitude, making them dimly perceptible through most binoculars."
ASV Journal Vol 24 No 3 June 1971: "faint and very extended in 6-inch 64x."
10x50 tripod-mounted, 1997-05-02 (clear skies, no light pollution on horizon, dew on binocs): 11' faint glow, 1 member resolved, averted vision reveals another 3 faint stars in the field forming a straight line. [RH]
24/05/93 01:54 Observing with a 6-inch f/8.6 Newtonian on 24/05/93, I found this dim cluster while sweeping at 52x. It is an elusive clsuter at 43x, appearing as an irregular glow to the southeast of an 8th mag star. This mottled grouping of very fine stars seems gathered into an elongated bar lying NE-SW. There is one 9th mag star, the rest are about 11th mag and fainter. I estimate the Trumpler class as III 1 R.
1998-05-25/26, 6-inch f/8.6 Newtonian, Jonkershoek (exurban). Lim mag 6.2 naked eye; seeing good; dew!
Large delicate cluster of very faint stars on an extremely rich field. There's one tiny star - the brightest at about 10th magnitude - which marks the southern end of an oblong patch, 7' x 1.3' in PA 25°, that contains the brightest of these dim stars. 104x is too much on this dim cluster tonight. In the sweeper eyepiece, the cluster appears twice as large as it vaguely merges into the background.
Readily seen near the end of a chain of stars pointing to Zeta Areae.
1997 April 05, 01:00 SAST, Coetzenburg, 11x80 tripod-mounted binoculars. Round, ghostly presence, detached from a small star due west; the Uranometria shows it touching the cluster.
The Messier objects
The Bennett objects
The Caldwell list
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