M24 - Sagittarius Star Cloud

Messier 24 or M24 (also designated IC 4715) is a Milky Way star cloud in the constellation Sagittarius. It has an apparent visual magnitude of 4.6 and its angular diameter is 90 arc-minutes. M24 lies at an estimated distance of 10,000 light years. The Equinox 2000 coordinates are RA= 18h 16.9m, Dec= -18° 30´ which makes M24 best seen during the summer. The Messier Summer Star Chart shows the position of all Messier objects visible during that season. As one of the more famous objects in the Messier Catalog, it is commonly known as the Sagittarius Star Cloud.

The image above shows the uncropped view of M24 through the Takahashi E-180 Astrograph (North is up). A 2x enlargement of this image appears to the right.

This Milky Way star cloud was discovered by Messier in 1764. It is unusual in that it does not consist of a single physical object. Rather, it is the juxtaposition of several bright clumps of interstellar dust and gas in the Milky Way along the line of sight. According to Stoyan et al. (2010), the distance of M24 ranges from 12,000 to 16,000 light years.

For more information, see the Messier Catalog as well as specific entries for M24 in Wikipedia and SEDS.

Messier's Description of M24

June 20, 1764
`Cluster on the parallel of the preceding [M23] and 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')

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