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NGC 6558 (14,971 of 18,816)

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NGC 6558

NGC 6558, Cl Collinder 368, C 1807-317, Cl VDBH 259, ESO 456-62, GCl 89, h 3731, GC 4382

RA: 18h 10m 18.38s
Dec: −31° 45′ 48.6″

Con: Sagittarius
Ch: MSA:1415, U2:377, SA:22

Ref: SIMBAD, Collinder (1931), SEDS

(reference key)

Type: globular cluster

Mag: B=12.39, V=11.29

Size: 4.2′
PA: ?

Historical observations

John Herschel (1847) Cape Observations

Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "globular, pB, irreg R, gmbM, composed of stars 16m, on a milky way ground of mixed L and vS stars." On a second occassion he called it "globular, pB, R, gbM, 80 arcseconds, resolvable or resolved in a field very full of milky way stars." His third observation was recorded as "globular, not vB, R, glbM, 2', resolved. The stars barely discernible."

Published comments

Hinks, A.R. (1911)

Hinks, A. R. (1911) On the galactic distribution of gaseous nebulae and of star clusters. MNRAS, 71(8), 693-701.

List 6: "NGC numbers of clusters classed as globular, not in Bailey's catalogue"

Bailey, S.I. A catalogue of bright clusters and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.

Harris, W.E. (1997)

RA 18 10 18.4 (2000) Dec -31 45 49 Integrated V magnitude 9.26 Central surface brightness, V magnitudes per square arcsecond 17.08 Integrated spectral type F7- Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 2.50c: Core radius in arcmin .03. ["Catalog Of Parameters For Milky Way Globular Clusters", compiled by William E. Harris, McMaster University. (Revised: May 15, 1997; from http://www.physics.mcmaster.ca/Globular.html; Harris, W.E. 1996, AJ, 112, 1487) ]

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a globular cluster.

Helwan Obs. Bulletin No 21 (1920)

vS cl. about 1'x1'; probably should be classed as globular.

Helwan Obs. Bulletin No 22 (1921)

Confirms HOB 21.

Melotte, P.J. (1915)

A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.

Modern observations

Steve Coe

Steve Coe, observing with a 13" f/5.6, notes: "Pretty bright, pretty small, round and has a very bright middle. I could resolve 10 members at 220X."

Contemporary observations

Auke Slotegraaf

1993 April 30

30/04/93: I searched in vain for this cluster with the 6-inch f/8.6 Newtonian at 52x and 72x.

Tom Bryant

2008-07-03 00:00:00

Observing site: Pinnacles overlook

Telescope: C-8

[18h 10m 18s, -31 46' 0"] A small, very faint cluster, not granulated. It was not easy at 163x, and was almost invisible at 36x

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