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RA: 18h 31m 23.23s
Dec: −32° 20′ 52.7″
Ch: MSA:1414, U2:378, SA:22
Ref: SIMBAD, SEDS, Corwin (2004)
Type: globular cluster
Mag: B=9.32, V=8.31
Messier 69 is the southern-most deep sky object on Messier's list (declination -32.35), narrowly beating Messier 70 (declination -32.29).
NGC 6637 is the globular cluster Messier 69; NGC 6634 = Lac I.11, an asterism slightly over 1° distant.
The NGC incorrectly identified Lacailles entry with NGC 6634, which is probably an asterism about 1° distant from Messier 69.
In the Philosophical Transactions, 1814, William Herschel wrote "I.51 and Connoissance des Temps [NGC 6637] are second miniatures of the 53d [NGC 5024]."
In the Philosophical Transactions, 1818, William Herschel wrote: "1784, 20 feet telescope. Very bright, pretty large, easily resolvable, or rather an already resolved cluster of minute stars. It is a miniature of the 53d of the Connoissance des Temps."
Messier discovered it in August of 1780, seeing at as "a nebula without star in Sagittarius... Near to it is a 9 mag star; the light is very faint; can be seen only in a good sky, and the least illumination of the micrometer wires extinguishes it... This nebula has been observed by M. de Lacaille and reported in his catalogue. It resembles the nucleus of a little comet. Diam. 2'."
James Dunlop observed this object from Paramatta, New South Wales, and included it as No. 613 in his catalogue of 1827. Using a 9-inch f/12 telescope, he described it as "a pretty bright round well-defined nebula, about 1 1/4' diameter, gradually condensed to the centre; there is a small star about 1' south of the nebula."
Sir John Herschel observing with his 18-inch f/13 speculum telescope found it "all clearly resolved into stars, 14-15 mag. A blaze of stars." He recorded it as "globular, B, R, vgbM, resolved into stars 14..15m, diam 10 seconds in RA." On a second occassion he called it "globular, pB, R, 3' diam, stars 14..15m." His third observation was recorded as "globular, vB, R, gvmbM, 3.5', all clearly resolved into stars 14..16m. A blaze of stars."
Burnham notes that in moderate telescopes it is a mere hazy spot, however, becoming truly impressive only in large instruments. The apparent diameter is given by various observers as 2' or 3'; it increases to about 4' on long exposure photographs."
A study by W. W. Morgan of Yerkes Observatory indicates this globular cluster to have a spectral type of G5.
RA 18 31 23.2 (2000) Dec -32 20 53 Integrated V magnitude 7.64 Central surface brightness, V magnitudes per square arcsecond 16.83 Integrated spectral type G2/3 Central concentration, c = log(r_total/r_core); a 'c' denotes a core-collapsed cluster 1.39 Core radius in arcmin .34. ["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) ]
Journal BAA, 36(3), Dec, p91
3' diam./ brighter parts.
"globular cluster, fairly condensed"
Bailey, S.I. (1908) A catalogue of bright stars and nebulae. Ann.Harv.Coll.Obs., 60(8), 199.
The RNGC (Sulentic and Tifft 1973) notes that this is a 9.0 mag globular cluster.
A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.
Hartung writes: "it is a beautiful well-resolved cluster about 2.5' across in a fine field with a bright star 4' Np, and is somewhat elliptical and moderately compressed with the outliers not widely scattered. Resolution is apparent with a 6-inch and it is an easy round haze with a 3-inch."
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 rather poor cluster, but in a pleasing field of stars. Looked distinctly elongated east-west."
Houston writes: "This 8th mag glow spans about 3'; in small telescopes it seems a bit brighter, in large ones a bit bigger." He adds that it does not stand out well from the rich milky way field.
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7.5M; 4' diameter; very soft and unresolved glow with brighter center; 8M star 5' NNW; not one of the more impressive M-objects, but fairly bright and easy to find; GLOB N6652 70' to SE."
Steve Coe, observing with a 13" f/5.6, notes: "(M 69) Very bright, large, round and has a much brighter middle. This bright globular can be seen in the 11X80 finder. At 165X and has ragged edges and many very faint stars are resolved across a smooth globe. I can also resolve 15 pretty bright stars in the central section. This very nice cluster looks like M 22 moved to the south. 6" f/6 22mm EP--bright, pretty large, irregularly round, much brighter middle, 8.8mm EP--bright, pretty large, elongated 1.5 X 1, much brighter middle, 3 stars resolved."
Location: Night Sky Caravan Farm, Bonnievale.
Date: 2016 Oct 30, Sunday.
Time: 22:37 SAST
Telescope: Little Martin (4-inch f/6.5 Celestron refractor)
11mm Nagler Type6 (60x): Reasonably faint and quite large globular cluster; broadly concentrated. Nice bright star (V=8.0) as companion.
30/04/93: Observing with a 6-inch f/8.6 Newtonian at 52x, this cluster is a pB, pL, round nebulous patch. It appears quite similar to the nearby NGC 6652, since both clusters have a field star to the north-west. The companion star of NGC 6637 lies closer than that of NGC 6652.
1997 July 9, Wednesday, 20:00 - 22:00 Jonkershoek. 11x80's tripod-mounted. Moderate conditions. A small, reasonably bright globular cluster, just like a slightly defocused star. Broad centre.
12-inch Meade, 40mm eyepiece, 53' fov. 1997-08-05, fair sky conditions "Small globular cluster brighter towards the middle, resembles a glimpse of a halo and somewhat elliptical shape. Compressed globular in a medium starfield. A whitish star visible a small distance from this globular in the field." [Magda Streicher, Pietersburg 23-53S, 29-28E]
12-inch f/10 SCT (EP: 2-inch 32mm SW 95x 42' fov; 2-inch 14mm UW 218x 23' fov)
This globular cluster displays a small bright compressed core, resembles a glimpse of a halo and somewhat oval shape. Combine beautifully with a white 8th magnitude star just 4' arc minutes to the northwest. Faint star points are visible in the outer hazy areas, short strings curl out into the field of view (95x). Discovered by lacaille in 1755 as class I no ii like a small comet nucleus.
Sky Conditions:The fainter parts of the Milky Way are barely visible.
Haziness only visible on the horizon.Atmosphere stable with little interference.
This small globular clusters stars is partially resolved and that the stars in this cluster are strongly concentrated towards each other as an out of focus halo of light.This globular clusters shape looks like an irregular cauliflower.In overall this cluster is moderately condensed.This globular cluster measures 3.5'x 2.5'.Chart No.327,NSOG Vol.2.
Instrument:12-inch Dobsonian Reflector Telescope.
Sky Conditions:The fainter parts of the Milky Way are barely visible on the horizon.
Transparency of the Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
Object Type:Globular Cluster.
First Impression:This object looks like a globular cluster.
Chart Number:No.18(Extract taken out of "Atlas of the Night Sky").
Size:26mm Eyepiece:Field Of View:57'/14= 4.0'.
20mm Eyepiece:Field Of View:50'/12.5= 4.0'.
4.0'+ 4.0'= 8.0'.
Size in Arc Minutes:4.0'.
Globular Cluster is 4.0'* 1.3'.
Brightness Profile:Right from the far outskirts of this globular cluster the nucleus is brighter than the central outskirts.
Challenge Rating:Moderately Easy.
In this globular cluster the individual stars are seen and that the stars are partially resolved.The stars are spherically concentrated towards each other like a swarm and that this cluster is compact.This cluster also has a slight elliptical shape and is well defined.
The Messier objects
The Bennett objects
The Caldwell list
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