Messier object

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The Messier objects are a set of astronomical objects catalogued by Charles Messier in his catalogue of Nebulae and Star Clusters first published in 1774. The original motivation behind the catalogue was that Messier was a comet hunter, and was frustrated by objects which resembled but were not comets. He therefore compiled a list of these objects.

The first edition covered 45 objects numbered M1 to M45. The total list consists of 110 objects, ranging from M1 to M110. The final catalogue was published in 1781 and printed in the Connaissance des Temps in 1784. Many of these objects are still known by their Messier number.

Because Messier lived and worked at astronomy in France in the Northern Hemisphere, the list he compiled contains only objects from the north celestial pole to a celestial latitude of about –35°. Many impressive Southern objects, such as the Large and Small Magellanic Clouds are excluded from the list. Because all of the Messier objects are visible with binoculars or small telescopes (under favorable conditions), they are popular viewing objects for amateur astronomers. In early spring, astronomers sometimes gather for "Messier marathons", when all of the objects can be viewed over a single night.