French astronomer Charles Messier died #OTD in 1817.
He is best known for his catalog, the Messier Catalog (contains 110 objects), which lists various astronomical objects, including nebulae, star clusters, and galaxies. Messier was primarily interested in comet hunting, and his catalog was created to help him and other astronomers differentiate between permanent celestial objects and comets, which could easily be mistaken for new discoveries.