sponsored by psychohistorian.org
RA: 18h 07m 20.64s
Dec: −24° 59′ 50.4″
Ch: MSA:1392, U2:339, SA:22
Ref: SIMBAD, Collinder (1931), Archinal&Hynes (2003), SEDS
Type: globular cluster
Mag: B=11.36, V=9.9
Synonyms: H II-197
Discovered in 1784 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "pB, pL, iR, r."
Described in the NGC as considerably faint, pretty large and of irregular form with mottled appearance.
Van den Bergh reported in 1967 that the brightest cluster member has a magnitude of 12.8
B cl., about 5'x5' irregular but probably should be classed as globular.
The RNGC (Sulentic and Tifft 1973) notes that this is a globular cluster.
RA 18 07 20.6 (2000) Dec -24 59 51 Integrated V magnitude 7.77 Central surface brightness, V magnitudes per square arcsecond 17.13 Integrated spectral type F9 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.63c: Core radius in arcmin .05. ["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) ]
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "9M; 1' diameter; faint and small; 50' off SE edge of M-8."
Steve Coe, observing with a 13" f/5.6, notes: "Pretty bright, pretty small, round, very compressed, 7 stars resolved at 220X. Averted vision makes it double in size."
"Very faint. Requires medium to high power." Gabriel Giust, 1994 April 10, 8-inch f/6.7 reflector, 9.7mm Super Plossl, San Isidro, Buenos Aires.
23 August 1993, 00:25 Observing with 11x80's from Stellenbosch, this cluster is distinctly seen as a dim spread-out glow needing attention. Nearby NGC 6553 was not seen.
1994-06-04 23:00, Die Boord, 11x80. Good seeing. This cluster can be seen as a cometary glow with a small star involved. Readily seen once found. Nearby NGC 6553, the smaller, seen with as much care.
1997 April 21. Jonkershoek. 11x80 tripod-mounted. No moon. Strange globular cluster - no sharp nucleus. Faint, round even glow. Looks more like a nebulosity.
Location: Jonkershoek Nature Reserve, Assegaaibosch Station
Date: 1998 July 31 / August 01, 01:00-02:40 SAST
11x80 tripod-mounted binoculars (9.5 mag stars at times not easy)
Sky conditions: Mediocre (transp. low, seeing average, dew) The skies are showing the effects of the combination of pollution (mainly from a nearby wood-processing plant) and a stable inversion layer, turning daytime skies grey-blue, and night skies ashen.
Modest surface-brightness globular, not much brighter to the middle which is broad.
Location: Vineyards outside Stellenbosch
I swept on to NGC 6544, one of the stranger globular clusters. With a variety of eyepieces (from 40x to 120x) it is noticeable how a number of faint field stars, scattered around near the cluster, make it appear like quite a large object (the brightest of these lie to the west (one star) and to the east (3 stars)). Only on a second look is it clear that the actual object here, a moderately faint glow, is separate from these stars. Remarkably, the shape of the globular is quite unclear – it is irregular and not round like one would expect and looks more like a nebula. At times, a single pinprick of light seems to shine within the nebulosity.
Location: Pietersburg South 23 53. East 29 28.
Sky conditions: Fair.
Instrument: Meade 12 inch.( Eyepiece super 40mm).
Date: 1997 August 05
Field of view: 52.7 minutes.
Similar in appearance to NGC 6528. Small faintly starlike, roundish with no stars and lanes. Small stars scattered around in a medium starfield.
12-inch f/10 SCT (EP: 2-inch 40mm SW 76x 53' fov; 2-inch 14mm UW 218x 23' fov; 2-inch 8.8mm UW 346x 15' fov)
Soft somewhat elongated northwest to south east even glow, very similar to NGC 6528. Slowly just barely brighter to the core. Outside the northeast border pinpoint stars are visible that extend to the east. Visual double of 11th magnitude just outside the globular to the east beautifully rounded it off.
Observing site: Pinnacles overlook
[18h 7m 18s, -25° 0' 0"] A small, faint cluster, barely granulated, with a couple of foreground stars in front of it.
Location:Night Sky Caravan Park,Bonnievale.
Sky Conditions:Whole Milky Way is visible.The sky is clean.
Atmosphere stable with little interference.
This globular cluster has a round shape and that this cluster is seen as a mottled halo of faint light.The stars in this globular cluster are unresolved because there is no resolution of stars in this cluster.The nucleus of this cluster is relatively compact and that the central core grows slightly brighter among the field of stars glowing softly in the starry background compared to the far outskirts of this cluster.This globular cluster measures 3'*3'.Chart:No.320,NSOG Vol.2.
The Messier objects
The Bennett objects
The Caldwell list
DOCdb is still in beta-release.
Known issues, feature requests, and updates on bug fixes, are here:
Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!
DOCdb is a free online resource that exists to promote deep sky observing.
You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.
Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.