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RA: 16h 18m 48s
Dec: −57° 56′ 0″
Ch: MSA:1512, U2:432, SA:26
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 22m
Mag: B=5.85, V=5.4
James Dunlop discovered this object from Paramatta, New South Wales, and included it as No. 326 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a group of very small stars of an irregular brnached figure, 15' or 20' diameter. The central part is very thin of stars."
Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "Cluster VIII class, larghe, loose, brilliant, irregular figure, fills field, chief star about 7th mag taken." On a second occassion he called it "Cluster VIII; large, coarse, bright, fills field, stars 7, 8, 9, 10th mag; a star about 7th mag taken."
Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.
Discussed, based of F-A plates.
Journal BAA, 36(3), Dec, p91
brighter stars at centre in two groups;
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
"Cat. of Open Cl. south of -45° Decl.", Mem. 17 Mnt Stromlo Obs.
"A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.
"very similar to NGC 6025; contains variable S. Normae." He gives the approx. diameter as 18 arcmin.
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 18' and the class as 2 3 m.
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
The RNGC (Sulentic and Tifft 1973) notes that this is a 6.0 mag open cluster.
15cm - irreg clumped cl led by ysh S Normae. 80x shows it 20' diam w/50 brtr
*s in addition to MW bkgrnd. fntr *s rel uncondensed, so perhaps this
cl is mostly brtr *s. BS, 27Feb1990, LCO.
Location: Night Sky Caravan Farm, Bonnievale.
Date: 2016 Oct 30, Sunday.
Time: 21:32 SAST
Telescope: Little Martin (4-inch f/6.5 Celestron refractor)
45mm Celestron Plossl (15x): Obvious scattered grouping in this wide-field view.
19mm Panoptic (35x): About 20 stars making a wobbly W or Sigma shape (the baseline of the W is oriented northeast-southwest). Many fainter stars in and around the W, with a very very bright star nearby.
1998-04-27/28, 11x80 tripod-mounted binoculars, Die Boord. Seeing average, transparency average, dew. "A bright star, perhaps orange [variable S Nor], surrounded by an irregular scattering of stars about 10' across. Large brightness range, with the brighter stars together, giving it an 1:4 elongated appearance, oriented east-west. An easy object."
Observing from the 1500 metre plateau of the SAAO observing site in Sutherland, 11x80 binoculars show this cluster as an irregular knot of stars with a bright red star on its northern edge. It is an irregular gathering of about a dozen or so stars, not very well separated from the rich milky way field.
Observing from Stellenbosch, 1983, this is an easy binocular object, with 8 bright stars standing out above the rest. It is poor and well spread out, even in a 2-inch refractor at 20x. Because of this, it appears nicer in binoculars, showing a diffuse patch of nebulosity. It contains a double star which is only easily seen at 30x with averted vision.
1997 Sept 03: 11x80 tripod-mounted. 23:00 SAST. Jonkershoek. Bright knot of stars. Three stars (a double, and an orange star) with several more scattered around. Look to the south; here two short chains of stars form an arrow-head; together with the cluster, this makes up a celestial flower, with the two chains forming the leaves, and the cluster blooming forth as the flower.
16-inch f/10 SCT (127x 290x)
I just love the clusters which express character in shape. NGC 6087 is a cluster with so much flare and state a point with a definite "V" shape. Two parts can be seen which work their way towards the north with sharp point impression although not connected. The western part of the two groups is larger and brighter and also house the magnitude 6.5 star S Normae. The western part is slightly fainter with less stars but play the V game to its full. To top it all the planetary nebula PK 327.7-05.4 situated towards the south and also in the part where the cluster is on its widest (not seen).
Alldays (22.50S, 20.12E, 770m).
12-inch f/10 SCT (76x, 218x)
This is an elongated scattering of lovely bright white diamonds in an east to west direction. The southern section of stars breaks down rather rapidly in contrast with the northern members, which sprays out into the field of view. The centre star show off a lovely yellow colour, and a half moon of stars take prominent stand on the western side in a north to south direction. This cluster is beautiful in its own right and well effective with smaller apertures. Triangle shape with a bright yellow 6Magnitude star to the north. Bright and mingle well with field stars. P/Nebula PK327.7-05.4 just 4' SE could not find. Will go back again soon.
The Messier objects
The Bennett objects
The Caldwell list
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