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RA: 15h 04m 24s
Dec: −54° 24′ 0″
Ch: MSA:968, U2:431, SA:25
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 22r
Mag: B=?, V=6.5
Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "cluster, vL, coarse, but rich and fine; diam in RA = 2 field in PD 25 (30' and 45'); stars 9, 10, 11, 12. General middle taken."
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Described in Union Obs. Circulars, 45-76, p 50. "Nebulae, clusters, etc. on Sydney Plates" as "a very rich open cluster of bright stars."
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 Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.
"loose; thin." He gives the approx. diameter as 45 arcmin.
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 40' and the class as 3 1 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 6.5 mag open cluster.
"Open clusters towards the Galactic center: chemistry and dynamics." arXiv:1008.3158v1 (2010 Aug 18)
Distance: 770 pc. Age: 1.00 Gyr. Orbit: perigalacticon = 7.02+/-0.11 kpc; apogalacticon = 9.42+/-0.06; e = 0.146.
Harrington calls this "unquestionably the best" deepsky object in Lupus. It is "a delightful open cluster for binoculars and fich-field telescopes. Viewing through 11x80 binoculars from the Florida Everglades (latitude 25 degrees) I recorded the group as a rich gathering of 8th mag and fainter stars set against the bright glow of other, unresolved cluster members."
1994-02-08, Die Boord, 11x80's tripod-mounted. This is one of three milky way patches I swept up. The other, NGC 5823, lies due south, and the third, not shown on the U2000, lies half a degree south and half a degree west. This latter object I will call Slotegraaf-de Kock 1. NGC 5822 appears as a very large patch of rich milky way stars, some 40' across, with many small stars seen but with countless others seen only as a background glow. Overall the distribution of stars seems quite even.
1997 Sept 03: 11x80 tripod-mounted. 23:00 SAST. Jonkershoek. Large, shy cluster of small and very small stars. No nebulosity of background glow. [Strange - compare with previous obs. on 1994-02-08]
1997-09-20, Sutherland (Karoo), SAAO plateau. 5-inch f/6 Newtonian. Skies excellent. In a 70' field of view, this wonderful cluster appears like a large, face-on spiral galaxy, with many long curved arms of stars.
6-inch f/8.6 Newtonian: 1997-10-02, Franschoek Pass viewing site. Obvious haze and thin clouds, sky fairly bright around horizon. "Beautiful delicate cluster, which fills a 40 arcmin field well. Stars of 10th magnitude and fainter and scattered, making a coarse grouping, but nevertheless a cluster."
1998-04-24/25, 11x80 tripod-mounted binoculars, Die Boord. Seeing average, transparency below average, dew. "Giant (26') patch of textured sky, rough with star specks. Field very rich; the cluster simply fades into the background. Even when sweeping its an obvious large woolly patch."
16-inch f/10 SCT (127x, 290x, 463x)
One of the most beautiful sprinkled clusters seen. Short strings intervene with one another, like a town seen out of an airplane at night. Not a very tight cluster but the stars share the space in harmony. The faint members run out of my field of view 127x and mingle well with the star field far above.
The Messier objects
The Bennett objects
The Caldwell list
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