Messier 24

Discovered on June 20, 1764 by Charles Messier.

Messier: M24.

June 20, 1764. 24. 18h 01m 44s (270d 26' 00") -18d 26' 00"
Cluster on the parallel of the preceding [M23] & near the end of the bow of Sagittarius, in the Milky Way: a large nebulosity in which there are many stars of different magnitudes: the light which is spread throughout this cluster is divided into several parts; it is the center of this cluster which has been determined [position]. (diam. 1d 30')

[Mem. Acad. for 1771, p. 444-445 (first Messier catalog)]
In the same night [June 20 to 21, 1764], I have discovered on the same parallel as the star cluster I have just been talking about & near the extremity of the bow of Sagittarius, in the milky way, a considerable nebulosity, of about one degree & a half extension: in that nebulosity there are several stars of different magnitudes; the light which is between these stars is divided in several parts. I have determined approximately the position of the middle of this cloud of light; its right ascension is 270d 26', & its declination 18d 26', south.
[p. 456] 1764.Jun.20. RA: 270.26. 0, Dec: 18.26. 0.A, Diam: 1.30. Cluster of stars which contains much nebulosity near the extremity of the bow of Sagittarius, on the parallel of the preceding star cluster [M23].

Bode: Bode 51.

A nebulous star cluster.

William Herschel

[Unpublished Observations of Messier's Nebulae and Clusters. Scientific Papers, Vol. 2, p. 652]
1783, Aug. 2. Considerable stars in great number.

John Herschel (1833): h 2004.

h 2004 = M24.
Sweep 269 (July 15, 1830)
RA 18h 8m 27.5m, NPD 108d 28' 13" (1830.0) [Right Ascension and North Polar Distance]
A glorious concentrated part of Milky Way, almost amounting to a globular cluster. Stars 14m and 15m.

Sweep 270 (July 16, 1830)
RA 18h 8m 28.9m, NPD 108d 29' 2" (1830.0)
Fine cluster of stars 15m; R; 6'; the stars are all of a size. The cl seems connected with the Milky Way.
Fine cluster of stars of 15th magnitude; round; 6' [diameter]; the stars are all of a size [same brightness]. The cluster seems connected with the Milky Way.

Smyth: DCXLII [642]. M24.

DCXLII. 24 M. Clypei Sobieskii [now Sagittarii].
AR 18h 08m 49s, Dec. S 18d 27'.5
Mean epoch of the observation: 1835.56 [July 1835]
A beautiful field of stars, below the sinister base of the Polish shield, and in a richly clustering portion of the Milky Way. This object was discovered by Messier in 1764, and described as a mass of stars -- a great nebulosity of which the light is divided in several parts. This was probably owing to want of power in the instruments useds, as the whole is fairly resolvable, though there is a gathering spot with much star dust [This is NGC 6603!]. A double star, H. and S. [Herschel and See] No. 264, follows in the sf quadrant, and a wider one sp, which is theit No. 263; these must be the objects alluded to by Piazzi, Nota 25, Hora XVIII., "Quatuor sequuntur ad austrum, quorum una dupley." A line led from Alpha Aquilae to the south-west over Lambda Antinoi, and configured as far again, reaches 24 Messier.

John Herschel, General Catalogue: GC 4397.

GC 4397 = h 2004 = M24.
RA 18h 10m 13.7s, NPD 108d 28' 7.3" (1860.0) [Right Ascension and North Polar Distance]
!; Cl; vRi; vmC; R; st 15 (Milky Way). 4 observations by W. & J. Herschel.
Remarkable; cluster; very rich; very much compressed; round; stars of 15th magnitude; in the Milky Way.
Remark: GC 4397 = h 2004 = M24. H.'s [William Herschel's] two observations hardly consist with this description, and their deviation in R.A. of nearly 4m from Messier's place makes it very doubtful whether he really saw this object.

Dreyer: NGC 6603.

NGC 6603 = GC 4397 = h 2004; M 24.
RA 18h 10m 14s, NPD 108d 28.1' (1860.0) [Right Ascension and North Polar Distance]
!, Cl, vRi, vmC, R, st 15 (M. Way)
Remarkable, cluster, very rich, very much compressed, round, stars of 15th magnitude, in the Milky Way.
Remark: 6603. h 2004 = M 24. h's [John Herschel's] two observations hardly consist with this description, and their deviation of nearly +3m from Messier's place makes it very doubtful whether he really saw this object. - J.H. [GC]

Barnard [IC 4715]

[AN 4239]

Dreyer: IC 4715.

IC 4715; Barnard (AN 4239), [M 24?].
RA 18h 18m ..., NPD 108d 30' +/- (1860.0) [Right Ascension and North Polar Distance]
RA 18h 20m ..., NPD 108d 29' +/- (1900.0)
eeL cloud of st and neb
Extremely excessively large cloud of stars and nebulosity.

Agnes M. Clerke:

(in 1905) "Visible to the naked eye as a dim cloudlet near Mu Sagittarii and named by Fr. Secchi as "Delle Caustiche" from the peculiar arrangement of its stars in rays, arches, caustic curves and intertwined spirals."

Curtis

[Descriptions of 762 Nebulae and Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
[B92,93 in M24]
...., RA=18: 9.6, Dec=-18:14. Two dark nebulae [B92, B93], noted by Barnard in Ap. Jour., Dec. 1913. The larger western object is about 14'x8', and the contrast between the dense Milky Way region and the vacant spots is very striking. The edges are less clear-cut, and the transition is less abrupt than in the object at 17h 56.6m [B ]. Professor Barnard's portrait lens photographs of these objects are reproduced in Lick Obs. Publ., 11, Plates 54 and 55. 0 s.n.