The Evolving Universe

Smithsonian Institution

What do NGC, IC, and M Mean?

illustration of a bowl of alphabet soup with some letters in a spoon

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These letters are abbreviations for astronomical catalogues—published lists of known stars, nebulae, supernova remnants, galaxies, and other objects in space.

The New General Catalogue (NGC) was originally published in 1888 by the Royal Astronomical Society and lists 7,840 objects.

The Index Catalogue (IC) lists an additional 5,286 galaxies, nebulae, and star clusters discovered between 1888 and 1907.

Names with the letter M are Messier objects, named after Charles Messier, a French astronomer. In the 1760s and 70s, he hunted comets and made a list of the 103 objects he found that looked like, but were not comets. All Messier objects can be seen with binoculars or small telescopes under clear, dark skies.