Messier 69

Discovered by Charles Messier on August 31, 1780.

Messier: M69.

August 31, 1780. 69. 18h 16m 47s (274d 11' 46") -32d 31' 45"
Nebula without star, in Sagittarius, below his left arm & near the arc; near it is a star of 9th magnitude; its light is very faint, one can only see it under good weather, & the least light employed to illuminate the micrometer wires makes it disappear: its position has been determined from Epsilon Sagittarii: this nebula has been observed by M. de La Caille, & reported in his Catalog; it resembles the nucleus of a small Comet. (diam 2')
[The credit to Lacaille's object (Lac I.11) is probably a misidentification! - hf]

[discovery announce in appendix of the Connoissance des Temps for 1783, p. 408]
On August 31, 1780, M. Messier has once again discovered two nebulae placed below the left arm & near the arc of Sagittarius, both on the same parallel; here are their positions,
274d 11' 46" in right ascension & 32d 31' 45" in southern declination [M69]
277. 13. 16. .................... 32. 31. 7. [M70]

[Mem. Acad. for 1771, p. 453-454 (first Messier catalog; objects not found)]
M. de la Caille, in a Memoir on the nebulous Stars of the southern pole, printed in the Volumes of hte Academy for 1755, page 194, reports the position of a nebula, which resembles, as he said, the small nucleus of a Comet, its right ascension was, for January 1, 1752, 18h 13' 41", & its declination 33d 37' 5" south.
On July 27, 1764, in an entirely serene sky, I have looked for this nebula carefully & in vain.

Lacaille: Lac I.11.

18:13:41, -33:37:05.
"It resembles a small nucleus of a comet."

When Messier looked for this object, he didn't find it in 1764, but when he observed again in 1780, he found both M69 and M70 close to Lacaille's position. He thought that with M69, he had rediscovered Lac I.11.
However, as Glen Cozens of Australia has pointed out, this is probably not the case, for the following reasons:

• M69 is much fainter than any other Lacaille object, and it is doubtful if that faint globular could have been seen with Lacaille's 1/2-inch aperture telescope.
• Lacaille's position deviates from that of M69 by about 1.2 degrees. This is an untypically large error, and cannot be easily assigned to a copy or grid error.
• There is a grouping of three stars of mag 8.3, 7.8, 8.7 at Lacaille's position, which in his modest instrument, could well have looked like a nebula.

In his GC, John Herschel did not follow Messier's identification but assigned an own GC number to Lac I.11, GC 5076 (see below), which consequently found its way into the NGC (NGC 6634).

Bode: Bode 46

"Like a small comet's nucleus."

Bode (1782): Sagittarius 161

[From: Vorstellung der Gestirne auf XXXIV Kupfertafeln (Introduction to the Stars on 34 Copper Plates), 1782. Here p. 25, plate 20]
Sagittarius 161, after Messier. RA = 274:11 [18:16.7], Dec = -32:30. Nebul. patch.

[Lac I.11]
Sagittarius 132, after Lacaille. RA = 273:51 [18:15.4], Dec = -33:37. Nebul. patch.

William Herschel

[PT 1814 p. 280, SP2 p. 539]
I.51 [NGC 6638] and Connoiss. 69 [M69 = NGC 6637] are second miniatures of the 53rd [M 53].

[PT 1818 p. 447, SP2 p. 600]
The 69th of the Connoissance. [M 69 = NGC 6637]
"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 [M53]."
By this observation, the profundity of this cluster must be of the 734th order.

Dunlop: Dun 613.

No. 613. A.R. 18:22:10, S.P.D. 57:28 (1827) [Right Ascension and South Polar Distance]
"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." 4 Observations.

John Herschel (1847): h 3747.

h 3747 = M. 69 = Dun 613.
Sweep 477 (August 1, 1834)
RA 18h 20m 14.1s, NPD 122d 27' 51" (1830.0) [Right Ascension and North Polar Distance]
Glob. Cl.; B; R; v g b M; resolved into st 14..15; diam 10.0s in RA.
Globular Cluster; bright; round; very gradually brighter toward the middle; resolved into stars of 14 to 15m; diameter 10.0s in RA [2.5'].

Sweep 478 (August 3, 1834)
RA 18h 20m 16.3s, NPD 122d 27' 11" (1830.0)
Glob. Cl.; p B; R; 3' diam; st 14..15 m.
Globular Cluster; pretty bright; round; 3' diameter; stars of 14 to 15 m.

Sweep 619 (August 15, 1835)
RA 18h 20m 16.7s, NPD 122d 27' 43" (1830.0)
Glob. Cl.; v B; R; g v m b M; 3 1/2'; all clearly resolved into stars 14..16 m. A blaze of stars.
Globular Cluster; very bright; round; gradually very much brighter toward the middle; 3 1/2' [diameter]; all clearly resolved into stars of 14 to 16 m. A blaze of stars.

John Herschel, General Catalogue: GC 4411.

GC 4411 [= h 3747] = M69 = Dun 613.
RA 18h 22m 13.2s, NPD 122d 26' 33.5" (1860.0) [Right Ascension and North Polar Distance]
Glob. Cl.; B; L; R; rrr; st 14..16. 4 observations by W. & J. Herschel.
Globular Cluster; bright; large; round; well resolved; stars from 14th to 16th magnitude.
Remark: Piazzi, in note on xviii.122 of his catalogue, says that both M69 and M70 are 1deg more to the south. But he is wrong.
[The GC doesn't include JH's 1847 entry h 3747, which is consequently lost as identification in the NGC, for unknown reasons - hf]

GC 5076 [introduced for Lacaille's wrong position].
RA 18h 20m 44.6s, NPD 123d 30' 27.3" (1860.0) [Right Ascension and North Polar Distance]
GC 5076 = Lac I.11
Neb. without stars. 0 observations by W. & J. Herschel.
Nebula without stars.

Dreyer: NGC 6637.

NGC 6637 = GC 4411 [= h 3747]; M 69, Dunlop 613.
RA 18h 22m 13s, NPD 122d 26.6m (1860.0) [Right Ascension and North Polar Distance]
Glob. Cl., B, L, R, rrr, st 14..16; = M69
Globular Cluster, bright, large, round, well resolved, stars of 14th to 16th magnitude.
Remark: Piazzi, in note on XVIII.122 of his catalogue, says that both M69 and M70 are 1deg more to the south. But he is wrong. - JH

NGC 6634 [Lac I.11].
NGC 6634 = GC 5076; Lac. I.11.
RA 18h 20m 45s, NPD 123d 30.5' (1860.0)
Neb, without stars.
Nebula without stars.

Curtis

[Descriptions of 762 Nebulae ans Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 6637, RA=18:24.8, Dec=-32:25. Bright globular cluster 3' in diameter. M. 69. 0 s.n.