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RA: 17h 19m 11.78s
Dec: −18° 30′ 58.5″
Ch: MSA:1371, U2:337, SA:22
Ref: SIMBAD, SEDS
Type: globular cluster
Mag: B=9.36, V=8.42
Messier observed this cluster in 1764, and the NGC describes it as "bright, large, round, extremely compressed in the middle, well resolved into 14th magnitude stars".
In the Philosophical Transactions, 1814, William Herschel described it as "a cluster of very compressed and extremely small stars. It is a miniature of the 53d [Messier]." In the Philosophical Transactions, 1818, William Herschel wrote: "1783, 10 feet telescope, power 250. I see several stars in it; and have no doubt a higher power and more light will resolve it all into stars. 1784, 1786, 20 feet telescope. a cluster of extremely compressed stars, it is a miniature of the 53d."
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, gmbM, 4', resolved into stars 14m."
Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part II. M.N.R.A.S., 35(8), 280.
"globular cluster, condensed."
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
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 7.13
A study by W. W. Morgan of Yerkes Observatory indicates this globular cluster to have a spectral type of F2.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.0 mag globular cluster.
RA 17 19 11.8 (2000) Dec -18 30 59 Integrated V magnitude 7.72 Central surface brightness, V magnitudes per square arcsecond 17.40 Integrated spectral type F5/6 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.15 Core radius in arcmin .58. ["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.
Bennett observed it with a 5-inch short-focus refractor, including it in his list of cometary objects as number 92.
Hartung descirbes the cluster as "large, rising broadly to the centre with irregular edges and well resolved, the scattered outliers about 3' across, some of which are visible with an 8-inch telescope. It is an easy object for a 3-inch telescope". The cluster measures 9' across and has an integrated magnitude of 7.9. The concentration rating is 8. Visually, the cluster is about 4' across and is located at the northern edge of the dark nebula Barnard 64.
Houston recalls observing this cluster from Mexico: "M9 was so bright and beautiful in the 7x50 that I tried repeatedly to see it with the naked-eye but unsuccessfully. This 7th mag cluster seemed about 5' in diameter, and even the Barnard dark nebula south and west of it stood out clearly without averted vision.
John Bortle (Webb Society Quarterly Journal, January 1976) using 10x50 binoculars, estimates the visual magnitude as 8.0.
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "8M; 9' diameter; scraggly and uneven for a GLOB; center little condensed; looks like very rich cluster; GLOB N6342 70' to SSE; GLOB N6356 is 80' to NE."
Donald J. Ware:"This globular cluster is about 6-8' in diameter, roughly circular, with some resolution at the edges. The core is unresolved in my scope, and is somewhat kidney bean shaped, and is elongated in the north to south direction. Under a clear, dark sky, see if you can find Barnard 64, the dark nebula upon which M-9 is superimposed. I saw it as an amorphous region, about 3/4 of a degree in extent, which is almost devoid of stars just to the west of the globular, and ever so slightly darker than the surrounding sky background."
Steve Coe, using a 13" f/5.6, notes: "M 9 is a large, bright globular cluster. The core is bright and oddly triangular in shape. There are chains of stars radiating outward at 135X. Dark nebula B64 is to the east. Along with B64 there is a dark area on the south side, within the cluster. Sentinel--easy in 11X80, shows fuzzy glob and dark oval to the west. 150X--Bright, large, round, extremely compressed, much, much compressed, only 12 stars resolved at this power. 330X-- the finest stardust! Still only 22* resolved, but averted vision shows a myriad of tiny stars at the limit of the 13" and a pretty bright bar of star in the core runs NE-SW and is about 2 arcmin long. 60X--Erfle 38mm shows a very compressed glob at the edge of a dark nebula and a rich star field to its' north. There is a nice orange star 15 arcmin south of M9, also at the edge of dark nebula B 64."
"10 Easy Globs!" by Marilyn Head (105 Owen Street, Newton, Wellington, Aotearoa / New Zealand; firstname.lastname@example.org)
"M9 is like a faint oval smudge and makes a nice contrast to the more rounded globulars in the same constellation. ... Although M9 and M19 have the same Shapley class of VIII, to an observer they differ in overall shape and 'texture' in that M9 has lots of what Hartung calls "outliers" i.e. stars scatttered away from the core, whereas M19 has almost none, the cluster appearing more homogeneous."
24/09/93: 11x80 binoculars, strong moonlight: A certain but very faint glow, in the middle of 1 side of a two-degree large right-angled triangle of 6th-7th mag stars.
1998-04-27/28, 11x80 tripod-mounted binoculars, Die Boord. Seeing average, transparency average, dew. "pB, R, broad nucleated haze, 5.7' across."
A 15.5-inch telescope at 220x shows it as a very fine, well populated globular cluster, small, compact and bright. Individual stars are easily seen, scattered across its disk at 330x. The stars appear evenly spread out, although there are a number of quite brighter stars which seem superimposed on the globular. The cluster appears regular in shape at 220x, but at 330x the mottled appearance of the cluster's edges give it an irregular shape. Examining the stars scattered across the field heightens the impression of brighter, nearby stars superimposed over the even mass of the globular. The cluster lies in the same two-degree field are the globulars NGC 6342 to the southeast and NGC 6356 to the north-east.
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.
Large (9arc min), bright round globular cluster with a large even bright core not starlike, shades out to irregular fringy edges. With careful observation fine dust stars scattered on this glob of light. Dusty nebulism to the west in the starfield.
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)
Large, bright and roundish globular cluster with a large even bright core, not star like, fades out to irregular fringy edges. Core is not quite round in shape (95x). With careful observation faint stardust can be seen scattered on this blob of light (218x). Faint stars are loosely gathered towards the west. Faint dusty nebulosity can be seen which is part of Barnard 64 nebula further west. (Mag 7.6; size 9.3'; brightest stars = 13.5 mag. )
Sky Conditions:The fainter parts of the Milky Way are barely visible.Haziness only visible on the horizon.Atmosphere stable with little interference.
M9 is a fine globular cluster where the stars in this cluster are well resolved into 7th to 8th magnitude stars and that the stars in this cluster are slightly loosely concentrated towards each other.This globular cluster has a large nucleus where the bright stars close to each other as stellar points.This cluster looks like an out of focus snowflake.This globular cluster measures 4.3'x 3'.Chart No:297,NSOG Vol.2.
Instrument:12"Dobsonian Reflector Telescope.
Sky Conditions:The fainter parts of the Milky Way are barely visible.
Transparency of the Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
First Impression:Globular Cluster.
Chart Number:No.117(Extract taken out of "Star Gazer's Deep Space Atlas").
Brightness Profile:High Surface Brightness.
Challenge Rating:Spectacular under dark skies in a large telescope.
Overall Shape:It is slightly oval with some irregularities towards the outskirts of this cluster.
Are individual stars seen? Yes,this cluster is partially resolved.
How are the stars concentrated towards the nucleus? It is spherically concentrated towards the center.
Estimate the size of the nucleus vs.halo: Nucleus(6.1') Halo(9.3')
Are there clumps/chains of stars? No.
Prominent empty spaces/starless patches? Yes,there are some starless patches around the outskirts of this cluster.
Observing site: Pinnacles overlook
[17h 19m 12s, -18° 31' 0"] A bright, glowing mass of stars. Approximately 100 seen with averted and direct vision. Averted vision was washed out by the brightness of the mass of stars.
The Messier objects
The Bennett objects
The Caldwell list
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