Messier 18

Discovered by Charles Messier on June 3, 1764.

Messier: M18.

June 3, 1764. 18. 18h 06m 16s (271d 34' 03") -17d 13' 14"
A cluster of small stars, a little below above nebula, No. 17, surrounded by slight nebulosity, this cluster is less obvious than the preceding, No. 16: with an ordinary telescope of 3.5-foot [FL], this cluster appears like a nebula; but with a good telescope one sees nothing but stars. (diam. 5')

[Mem. Acad. for 1771, p. 443 (first Messier catalog)]
In the same night [June 3 to 4, 1764], I have discovered a bit below the nebula reported here above, a cluster of small stars, environed in a thin nebulosity; its extension may be 5 minutes of arc: its appearances are less sensible in an ordinary [non-achromatic] refractor of 3 feet & a half [FL] than that of the two preceding [M16 and M17]: with a modest refractor, this star cluster appears in the form of a nebula; but when employing a good instrument, as I have done, one sees well many of the small stars: after my observations I have determined its position: its right ascension is 271d 34' 3", & its declination 17d 13' 14" south.
[p. 456] 1764.Jun.3. RA: 271.34. 3, Dec: 17.13.14.A, Diam: 0. 5. Cluster of small stars, which contains a slight nebulosity, a little below the train of light which has been mentioned.

Bode: Bode 53.

Star cluster with nebula.

William Herschel:

[Unpublished Observations of Messier's Nebulae and Clusters. Scientific Papers, Vol. 2, p. 652]
1783, July 31. About 20 L. [large; bright] and sev. S. [several small; faint] stars irregularly scattered.
1784, June 22 (Sw. 231). A cl. [cluster] of coarsely scattered L. [large; bright] stars, not rich.

John Herschel (1833): h 2007.

h 2007 = M18.
Sweep 270 (July 16, 1830)
RA 18h 10m +/-, NPD 107d 11' 42" (1830.0) [Right Ascension and North Polar Distance]
A poor and coarse cluster. Contains about a dozen stars 10m and 15 or 20 more 12 .. 15m.

Smyth: DCXLIV [644]. M18

DCXLIV. 18 M. Clypei Sobieskii [now Sagittarii].
AR 18h 10m 36s, Dec S 17d 11'.7
Mean epoch of the Observation: 1835.56 [July 1835].
A neat double star, in a long and straggling assemblage of stars,below the Polish shield. A 9 and B 11 [mag], both blueish. This cluster was discovered by Messier in 1764, and registered as a mass of small starsappearing like a nebula in a 3 1/2-foot telescope; which affords another instance that the means of that very zealous observer did not quadrate with his diligence. The whole vicinity is, however, very rich, and there are several splendid fields about a degree to the south of this object. It was also [as M16] differentiated from Mu Sagittarii, for which it lies 4deg to the north-by-east, in the direction of Epsilon in the Eagle's tail.

John Herschel, General Catalogue: GC 4401.

GC 4401 = h 2007 = M18.
RA 18h 11m 44.6s, NPD 107d 11' 8.1" (1860.0) [Right Ascension and North Polar Distance]
Cl; P; vlC 4 observations by W. & J. Herschel.
Cluster; poor; very little compressed.

Dreyer: NGC 6613.

NGC 6613 = GC 4401 = h 2007; M 18.
RA 18h 11m 45s, NPD 107d 11.1' (1860.0) [Right Ascension and North Polar Distance]
Cl, P, vlC; = M18
Cluster, poor, very little compressed.