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RA: 17h 44m 54.71s
Dec: +03° 10′ 12.5″
Con: Ophiuchus
Ch: MSA:1273, U2:248, SA:15
Ref: SIMBAD, Collinder (1931), SEDS
Type: globular cluster
Mag: B=?, V=10.9
Size: 4.2′
PA: ?
Photos (1)
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Synonyms: H II-587
Discovered in 1786 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "F, cL, iF."
Included in a list of doubtful objects;. Very faint and poor; suggestion of a background on Mount Wilson plates.
The RNGC (Sulentic and Tifft 1973) notes that this is a 12.5 mag globular cluster.
RA 17 44 54.7 (2000) Dec +03 10 13 Integrated V magnitude 11.01 Central surface brightness, V magnitudes per square arcsecond 20.37 Integrated spectral type G1:- Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.70 Core radius in arcmin .26. ["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) ]
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "12M; 2' diameter; small and faint with little brighter center; unresolved."
Observer: Dave Mitsky (e-mail: djm28@psu.edu)
Instrument: 17-inch other Location: Harrisburg, Pa, U.S.A.
Light pollution: moderate Transparency: fair Seeing: fair
Time: Fri Jun 27 04:30:00 1997 UT Obs. no.: 155
I also located 2 new Herschel globulars that night, namely NGC 6144 near Antares and NGC 6426 northwest of Gamma Ophiuchi. NGC 6426 was particularly faint, being just at the limit of visibility with averted vision.
Steve Coe, using a 13" f/5.6, notes: "Pretty faint, pretty large, elongated 1.5 X 1 in PA 25, somewhat brighter in the middle, 10 stars resolved at 100X from Cherry Rd. This a low surface brightness object."
In my opinion, the toughest NGC-globular would be NGC6749 in Aquila. It has
also wrong coordinates in many sources, has a low surface brightness and is in
a rich star field. NGC7492 in Aquarius, NGC6426 in Ophiuchus and NGC1049 in the
Fornax Dwarf are other NGC-toughies.
0.2 deg SE of NGC6380, there is a dark nebula called SL28. Has anybody
seen it?
/Timo
------------------------------------------------------------------------
Timo Karhula "Amateur astronomers are * *
E-mail: atotika@ato.abb.se nocturnal creatures" * * *
ICBM: +59d52'13" +16d05'22"
----------------------------------------------------------- * *
1997 July 7, Monday, 21:00 - 24:00 Jonkershoek. 11x80's tripod-mounted. Very careful study; nothing found.
Observing site: Little Bennett Regional Park
Telescope: C-11
[17h 44m 54s, 3° 0m 0s] An extremely faint cluster, invisible in the 30mm, hardly seen in the 18. No resolution.
Lacaille's catalogue
The Messier objects
Dunlop's catalogue
The Bennett objects
The Caldwell list
Named DSOs
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