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RA: 18h 18m 0s
Dec: −12° 14′ 0″
Ch: MSA:1344, U2:294, SA:15
Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)
Type: open cluster, 13mn
Mag: B=7.06, V=6.5
It is possibly a member of the Serpens OB 2 Association.
Synonyms: H VIII-015
Discovered in 1785 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a cluster of coarsely scattered stars."
Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "a poor cluster class VIII having coarse stragglers to a great distance. The chief star about 7m taken."
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 2.8' and the class as 1 3 p.
Vorontsov-Velyaminov, B. "Integral magnitudes of south star clusters", Astron. Nach. 228, 325. Comparing the brightness of the cluster with the extrafocal images of stars, he estimates the magnitudes as 8.5
Moffat, AFJ & Vogt. N. (1975) "Southern Open Star Clusters VI. UBV-H-beta Photometry of 18 Clusters from Centaurus to Sagittarius." Astron.Astrophys.Suppl., 20, 155-182. [image, table]
d = 1.64 kpc.
The RNGC (Sulentic and Tifft 1973) notes that this is a 8.0 mag open cluster.
While trying to finish up the summer Herschel II's, I ran into a large and rather interesting faint nebula surrounding the open star cluster NGC 6604 in Serpens. The cluster itself is a moderate-sized group of perhaps 15 stars in a rich starfield. Enveloping the cluster is a very large faint nebula which seems to be over a degree wide. It extends a little more to the east and north from the cluster than it does to the west or south, and with the UHC filter shows some interesting light and dark detail resembling that of portions of the Rosette. The brightest area is a smaller diffuse patch north of the cluster proper, but the somewhat sinuous dark lanes make this entire area worth a visit. Clear skies to you. David Knisely
Observing site: Little Tycho Observatory
[18h 18m 6s, -12° 14' 0"] A group of 4 bright star, close together in a very rich part of the milky way. Confirmed on WikiSky.
The Messier objects
The Bennett objects
The Caldwell list
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