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NGC 6304 (14,280 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




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NGC 6304

NGC 6304, C 1711-294, Cl VDBH 216, ESO 454-2, GCl 56, Bennett 90, I 147, h 3670, GC 4275

RA: 17h 14m 32.51s
Dec: −29° 27′ 44.2″

Con: Ophiuchus
Ch: MSA:1417, U2:376, SA:22


(reference key)

Type: globular cluster

Mag: B=10.33, V=9.03

Size: 8′
PA: ?

Historical observations

William Herschel (c.1784)

Synonyms: H I-147

Discovered in 1786 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "vB, R, gmbM, 2.5' diameter." In the Philosophical Transactions, 1814, Herschel described it as "a miniature of the 62d of the Connoissance des Temps [NGC 6266] which is a miniature of the 3d [NGC 5272]."

John Herschel (1847) Cape Observations

Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "globular, B, R, gbM, diam in RA = 6 seconds, resolved into stars 16..17th mag." On a second occassion he called it "B, R, at first s, then vglbM; brighter part 2' diameter, but there is a much fainter portion which extends a good deal further; stars 16..17th mag."

Published comments

Helwan Obs. Bulletin No 22 (1921)

! B globular cluster some 10' in diameter. There is a strong suggestion that the outer stars in the n.f. portion have been absorbed, giving the cluster an unsymmetrical appearance.

Bailey, S.I. (1908)

"globular cluster, condensed."

Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 10.0 mag globular cluster.

Harris, W.E. (1997)

RA 17 14 32.5 (2000) Dec -29 27 44 Integrated V magnitude 8.22 Central surface brightness, V magnitudes per square arcsecond 17.34 Integrated spectral type G3- Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.80 Core radius in arcmin .21. ["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) ]

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

Tom Lorenzin

Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "9M; 2' diameter; round and bright; compressed center; unresolved glow of 16M and dimmer stars."

A study by W. W. Morgan of Yerkes Observatory indicates this globular cluster to have a spectral type of G5.

Observer: John Callender

Instrument: 8-inch Dobsonian reflector Location: Carpinteria, CA, USA

Light pollution: light Transparency: fair Seeing: good

Time: Sat Jul 5 07:20:00 1997 UT Obs. no.: 195

A faint, small fuzzy patch. Roughly circular and slightly condensed, fairly easy at 49x.

1997 March 15. Jonkershoek. 11x80 tripod mounted. No moon. Quite remarkable. A small, round glow, like an out-of-focus star, but set in a very rich milky way backdrop; yet seen easily with averted vision.

Steve Coe

Steve Coe, using a 13" f/5.6, notes: " Pretty faint, pretty small, round brighter in the middle and resolved at 135X."

Contemporary observations

Magda Streicher

1998 April 27

Location: Campsite (South 23 16 East 29 26).

Sky conditions: Very clear semi transparent.

Instrument: Meade 8" (Super plossl 26mm and wide-angle 18mm eyepiece).

Date: 26 to 28 April 1998.

Field of view: 36.2arc minutes.

About the same size as NGC 6293. This soft even glow slowly brightens to a not so bright core and mingles well with a delicate starfield. With a 18mm wide-angle it resembles a more granular look but no resolved stars.

(no date)

12-inch f/10 SCT (EP: 2-inch 40mm SW 76x 53' fov; 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov)

This soft even small glow slowly brightens to a not so bright core and mingles well with a delicate star-field. It resembles (218x) a more granular look with a soft outer envelope. The edges however look frizzy and with averted vision a few faint star points can be seen. Not a very tight cluster. (Mag 8.4; size 6.8'; brightests stars = 14.2 mag. )

Tom Bryant

2008-07-03 00:00:00

Observing site: Pinnacles overlook

Telescope: C-8

[17h 14m 30s, -29 28' 0"] A small faint patch, smaller than it's listed 8 arc minute diameter.

Richard Ford

2012 August, 19th


Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.

Instrument:12-inch Dobsonian.

The shape of this globular cluster looks like a fairly bright snowball and that this clusters stars has a granular appearance where some of the stars in this cluster are resolved.The nucleus of this globular cluster is centrally concentrated.The nucleus of this globular cluster however grows somewhat brighter compared to the stars right on the far outskirts of this cluster.Chart No.297, NSOG Vol.2.

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