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RA: 16h 17m 2.51s
Dec: −22° 58′ 30.4″
Ch: MSA:1398, U2:336, SA:22
Ref: SIMBAD, SEDS
Type: globular cluster
Mag: B=8.7, V=7.87
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Better known as Messier 80, the NGC describes this globular cluster as: "very remarkable object, globular cluster of stars, very bright, large, very much brighter towards the middle (variable star involved), resolved to the core, consisting of 14th magnitude stars" The reference to a variable star is cleared up by Dreyer's Note appended to the object, on page 224 of the NGC: "Auwers saw a new star of the 7th magnitude on May 21, 1860, which was also found by Pogson on the 28th, and remained visible until about June 10. This phenomenon bears a close resemblance to the "new star" in the Andromeda nebula in 1885."
In the Philosophical Transactions, 1814, William Herschel wrote "May 26, 1786. 20 feet telescope. The 80th of the Connoissance des Temps is a beautiful, round cluster of extremely minute and very compressed stars about 3' or 4' in diameter, by the increasing compression of the stars the cluster is very gradually much brighter in the middle." In the Philosophical Transactions, 1818, William Herschel wrote: "1784, 1786, 20 feet telescope. A globular cluster of extremely minute and very compressed stars of about 3 or 4' diameter; very gradually much brighter in the middle; towards the circumference the stars are distinctly to be seen, and are the smallest imaginable."
Observed by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "globular, vB, R, svvmbM to a blaze; diam in RA = 10.5 seconds. Stars 15th mag, all well seen." On a second occassion he called it "globular, vm comp M, psvmbM, diam 12 seconds, stars = 14th mag; all resolved. Fine object."
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part IV. M.N.R.A.S., 36(2), 58.
"! globular cluster, condensed"
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
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 7.6.
The RNGC (Sulentic and Tifft 1973) notes that this is a 8.5 mag globular cluster.
RA 16 17 02.5 (2000) Dec -22 58 30 Integrated V magnitude 7.33 Central surface brightness, V magnitudes per square arcsecond 15.19 Integrated spectral type F6 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.95 Core radius in arcmin .15. ["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: "(M 80) Bright, large, little elongated, very bright in the middle at 165X. There are several dark lanes nearby and I can resolve about 50 stars at 165X.; 36" f/5 TSP 96 129 stars resolved in 20mm Nagler; 6" f/6 Dugas bright, pretty large. With 8.8mm EP only 2 stars resolved with direc vision, but aviz brings out 20 or more, the stars just explode from the stippled background. There is a very bright middle with 3 layers to the brightness contour.
Harrington, P. (1986) An observer's guide to globular clusters. Sky&Telescope, Aug, 198.
'The richest and most condensed mass of stars which the firmament can offer' wrote William Herschel in 1785. under ideal conditions an 8inch may begin to resolve some of the 14th mag stars, but resolution is hindered by the clusters high density.
Stewart Moore (Fleet, Hampshire, UK), observing with a 12-inch f/5, writes in the The Webb Society Nebulae and Clusters Section Report No. 10, July 1992: "A small, round cluster with an intense stellar centre. Easily resolved at the edges, although the remainder of the cluster could not be resolved, even at high powers."
NGC 6093 M-80 Donald J. Ware:"Seen in binoculars as a fuzzy star, this is a small, highly concentrated globular cluster which is only partially resolved around the edges in my telescope. The center appears somewhat granulated."
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7.2M; 9' diameter; very strong central condensation; resolved into individual stars at 166x; beautiful! midway between Antares (Alpha SCO) and Graffias (Beta SCO)."
Observer: John Callender
Instrument: 8-inch Dobsonian reflector Location: Carpinteria, CA, USA
Light pollution: light Transparency: fair Seeing: good
Time: Sat Jul 5 07:40:00 1997 UT Obs. no.: 193
Easy to spot at 49x. Much more like a "classic" globular in appearance than M4; a circular glow with a condensed center. Could not resolve it at 122x or 244x.
"10 Easy Globs!" by Marilyn Head (105 Owen Street, Newton, Wellington, Aotearoa / New Zealand; firstname.lastname@example.org)
"Further to the left , M80 lies directly in line with Antares and the gorgeous double star Beta Scorpii (actually a quintuple!). It is tiny and concentrated with a fuzzy shell which made its discoverer, Mechain, compare it with a comet."
ASSA DSOS: Ed Finlay, observing with a Meade 4-inch ED APO refractor from Johannesburg, 1992 May 24, notes "Nothing like Omega Cen. A faint fuzzy cloud 1/3 size of M4 and easy to miss. About 8 arc min diameter."
30/04/93: A 6-inch f/8.6 Newtonian at 52x shows this as a small but bright globular cluster. It shares the 1 degree field with a handful of bright stars, one of which is close north-east. The cluster is easy to spot in the 6-inch, even though I was not dark-adapted yet -- the superposed star shown on Uranometria could not be seen.
24/09/93: 11x80 binoculars, strong moonlight: Easy to see as a fuzzy star. Has a star close to the northeast, of very similar magnitude.
Location: Pietersburg South 23o 53. East 29o 28.
Sky conditions: Clear.
Date: 4 Julie 1997.
Field of view: 52.7 arc minutes.
ASSA-DSO - Report J
NGC 6093 mag 7
Small, dense bright core, lot of nebulis around
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 ).
Date: April 1997.
Bright large globular cluster with a bright and condensed core. Stars faintly reveal themselves scattered out in a variable starfield.
12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov)
Bright, medium size globular cluster with an exceptional large and bright core. The unresolved tight core grows about two-thirds in size. Star outliers noticeable prominent in the thinner outer third of the globular edge and mingles well with the scattered framed star-field (218x). A beautiful 8.4 magnitude white star is situated just 3' arc minutes to the northeast. It is situated approximately halfway between Antares and Beta Scorpii.
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
At both 57x and 75x this globular clusters stars has a granular appearance where some of the stars in this cluster is resolved and that this cluster is moderately large and condensed.This cluster looks like an oval snowball in appearance.This globular cluster measures 3.7'x 3'.Chart No:337, NSOG Vol.2.
Telescope:12"-inch Dobsonian Reflector Telescope
Eyepieces: 26mm Super Wide Angle Eyepiece.
20mm Ultra Wide Angle Eyepiece.
Sky Conditions: The fainter parts of the milky way are barely visible.
Transparency of the Sky: Haziness only visible on the horizon.
Seeing: Atmospher stable with little interference.
Limiting Magnitude: 4.5.
First Impression: Globular Cluster.
Chart Number: No.18(Extract taken out of "Atlas of the Night Sky").
Size: 26mm Eyepiece: 57'/9=6.3'
20mm Eyepiece: 50'/8=6.2'.
Size in Arc Minutes: 6.2'.
Size of nucleus vs. halo: 9/6.2'=1.4'.
Size of halo: 1.3'.
Globular Cluster is 6.2'*3.1'.
Brightness: Very Bright.
Brightness Profile: High Surface Brightness.
Challenge Rating: Absolutely stunning to observe in a large telescope.
This bright globular has a slightly oval and granular appearance of bright stars which is just resolvable. Although this cluster is centrally condensed almost like a snowball. The stars in this globular cluster is shpherically concentrated towards each other.
Observing site: Little Tycho Observatory
[16h 17m 0s, -22° 59' 0"] AKA NGC 6903. A faint ball of mist, awash in the light pollution of our urban, southern sky. Needs a revisit in dark skies, this is a spectacular cluster there.
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