An astronomical catalog or catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery. The oldest and largest are star catalogues. Hundreds have been published, including general ones and special ones for such items as infrared stars, variable stars, giant stars, multiple star systems, star clusters, and so forth. General catalogs for deep space objects or for objects other than stars are also large. Again, there are specialized ones for nebulas, galaxies, X-ray sources, radio sources, quasars and other classes. The same is true for asteroids, comets and other solar system bodies. Astronomical catalogs such as those for asteroids may be compiled from multiple sources, but most modern catalogs are the result of a particular astronomical survey of some kind. Since the late 20th century catalogs are increasingly often compiled by computers from an automated survey, and published as computer files rather than on paper. Catalogs of historical importance Ptolemy's Almagest is published in 1st century AD. It remained the most authoritative text on astronomy for over 1500 years. It details over 1022 stars, constellations, galaxies and nebulae along with their positions along with their ecliptic coordinates and magnitudes. It also describes in detail the construction of instruments to aid in Astronomical investigations. Azophi's Book of Fixed Stars, published in 964, describes more than a thousand stars in detail and provides the first descriptions of the Andromeda Galaxy and the Large Magellanic Cloud. Tycho Brahe completed his catalogue with the positions and magnitudes of 1004 fixed stars in 1598. It was the major achievement in astronomy since the days of Ptolemy. The astronomical observations of Tycho Brahe greatly improved the positional accuracy achieved by his predecessors. Johann Bayer's Uranometria star atlas was published in 1603 with over 1200 stars. Names are made of Greek letters combined with constellation name, for example Alpha Centauri. John Flamsteed's Historia coelestis Britannica star atlas, published in 1725, lists stars using numbers combined with constellation and ordered by right ascension, for example 61 Cygni. Messier Catalog – The Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771. Nebulae and Star Clusters was published in 1781, with objects M1 – M110. New General Catalogue compiled in the 1880s by J. L. E. Dreyer, lists objects NGC 0001 – NGC 7840. The