Messier Object List

About this list

Charles Messier, a French comet hunter, compiled his catalog of nebulae and star clusters so that comet observers would not be fooled by fuzzy objects that never move. His final published list, in the Connaissance des Temps for 1784 (published 1781), reached 103 entries; M104 through M110 are later additions that historians credit to objects recorded by Messier and his colleague Pierre Mechain. The values here are compiled from commonly published references, principally the SEDS Messier database and standard almanac tables, cross-checked against other modern summaries.

Treat every number as typical rather than definitive. Visual magnitudes of extended objects, angular sizes, and especially distances vary noticeably between sources: integrated magnitudes depend on how much of a faint outer halo is included, and galaxy distances carry real measurement uncertainty, sometimes tens of percent. Coordinates are J2000 positions rounded to a tenth of a minute of time in right ascension and a minute of arc in declination, which is ample for finding charts but not for telescope pointing catalogs. M102 is listed here as the lenticular galaxy NGC 5866 in Draco, its most common modern identification, though some historians consider it a duplicate observation of M101. M40 is a double star, M73 a chance asterism of four unrelated stars (so no single distance applies), and M24 a star cloud of the Milky Way rather than a single deep-sky object.

The best-season column uses one simple rule: the season, for mid-northern observers, in which the object culminates (crosses the meridian) around 10 pm local time, computed from its right ascension. Seasonal boundaries are soft, most objects are observable for a few months on either side, and far-northern objects such as those in Ursa Major, Draco, and Cassiopeia are circumpolar from much of the northern hemisphere and can be found on almost any clear night.

The optional latitude check uses the horizon geometry rule that an object never rises when the difference between your latitude and its declination exceeds 90 degrees; from northern latitudes that means declination below your latitude minus 90. This assumes a perfect sea-level horizon, ignores atmospheric refraction and each object's angular extent, and says nothing about practical visibility: an object that culminates only a few degrees up is effectively out of reach long before it fails this test. The latitude you enter is used only inside your browser for this comparison. This page is a planning and education reference, not an authoritative almanac record.