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RA: 16h 27m 40.43s
Dec: −38° 50′ 55.6″
Ch: MSA:1441, U2:375, SA:22
Ref: SIMBAD, SEDS
Type: globular cluster
Mag: B=11.03, V=9.68
James Dunlop discovered this object from Paramatta, New South Wales, and included it as No. 536 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a round nebula, about 1' diameter, bright immediately at the centre, and very faint from the bright nucleus to thge margin. Another observation makes the figure rather ellliptical, with a bright nucleus."
Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "pB, R, pgbM, resolvable, with left eye I can barely discern a few of the stars." On a second occassion he called it "B, R, pgbM, resolvable, 2'." His third observation was recorded as "vB, R, pL, pgmbM, 2.5'. Evidently a globular, but moonlight very bright and near full, and I cannot see the individual stars." The final record reads: "B, R, psbM, 200 arcseconds, resolvable."
The NGC records it as "bright, pretty large, round, pretty suddenly brighter towards the middle, partially resolved, some stars seen."
10'x10', rather irr. globular cluster; the stars are very dense at the centre.
The RNGC (Sulentic and Tifft 1973) notes that this is a 10.5 mag globular cluster.
Hartung notes that with a 12-inch the cluster "appears granular with glimpses of very faint outliers. It is about 1.5' across, a fairly symmetrical round haze, quite plain with a four-inch."
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "10M; 4' diameter; bright, large and round unresolved glow with brighter center."
RA 16 27 40.4 (2000) Dec -38 50 56 Integrated V magnitude 8.99 Central surface brightness, V magnitudes per square arcsecond 17.30 Integrated spectral type F6/7 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.80 Core radius in arcmin .14. ["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) ]
Steve Coe, observing with a 17.5" f/4.5 at 100X, notes: "Bright, pretty large, very bright in the middle at 100X. Going to higher power at 165X, it has a stellar nucleus and two stars are resolved in good seeing. Averted vision makes it grow.
In 11x80 binoculars, "inconspicuous" pretty much sums it up. Careful observation shows a faint patch, looking like an extended faint star. Easy once you know where to look.
In 15.5-inch reflector this cluster is easy to find, appears pretty bright has a concentrated nucleus - the nucleus is about 20" across, much like the disk of the planetary NGC 6153 which lies nearby.
Location: Camp Site: ( South 23 16 East 29 26 )
Sky conditions: clear fair about 6 magnitude.
Instrument: 8 inch Meade ( super wide-angle 18 mm. Eyepiece ).
Bright, small round globular cluster, with a very bright middle. I can't resolve any stars, only a little haziness to the edges in a medium starfield.
12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov; 2-inch 8.8mm UW 346x 15' fov)
Bright, small round globular cluster, with a very bright core. The edges seems to be very hazy against the bare star-field. A rather convex appearance (346x) to the northeast might be attributed to the density of stars, although I could not discern any.
Observing site: Pinnacles overlook
[16h 27m 42s, -38° 51' 0"] Faint, diffuse, unresolved cluster, small, bright nucleus.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
The shape of this globular cluster has the appearance of a mottled snowball.The stars in this globular cluster are unresolved and that this cluster looks condensed.The nucleus of this globular cluster is relatively compact.The nuclues of this globular cluster is somewhat brighter compared to the stars on the outskirts of this cluster.Chart No.340,NSOG Vol.2.
The Messier objects
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