New General Catalog (NGC), standard reference list of nebulae (see nebula). It is based on the General Catalog, published in 1864, which included 2,500 nebulae cataloged by William Herschel and an additional 2,500 cataloged by his son, John Herschel. The General Catalog was combined with work of other observers and the resulting total of more than 7,800 entries was published as the New General Catalog of Nebulae by J. Dreyer in 1888. This work was updated by publication of two Index Catalogs (IC), in 1895 and 1910. More than 13,000 objects are listed in these works, of which more than 12,000 are extragalactic nebulae (galaxies). Some nebulae listed in the NGC are also listed in the Messier catalog, e.g., the Andromeda Galaxy is listed both as NGC 224 and as M31.