Astrophysics (index)about

Messier Catalog

(M, Messier Objects, Catalogue des Nebuleuses et des Amas d'Etoiles, Catalogue of Nebulae and Star Clusters, Messier Catalog)
(catalog of astronomical objects to avoid when looking for comets)

The Messier Catalog (or list of Messier Objects or Catalogue des Nebuleuses et des Amas d'Etoiles, i.e., Catalogue of nebulae and Star Clusters) is Charles Messier's 1771 catalog of fixed but apparently-non-stellar astronomical objects, of which most are now known to be galaxies. Messier was interested in finding comets and produced this list of objects that look like comets but had been established to be something else. The objects are designated M with a number (examples: Andromeda (M31), Triangulum Galaxy (M33), M82, M87) and include galaxies, clouds, and clusters of stars. All that can be currently identified are also in the New General Catalogue. The Messier designations are still often used by astronomers.

(catalog,galaxies,nebulae,star clusters)
MM87Messier Catalog 
MM85-HCC1Messier Cataloggalaxy near M85

Referenced by:
astronomical catalog
Caldwell Catalog
Whirlpool Galaxy (M51a)
Spindle Galaxy (NGC 5866)
Virgo Cluster