The Caldwell Catalog was compiled by famous English astronomer
Sir Patrick Moore as a modern version of the Messier Catalog.
Moore noted that the Messier list existed initially for the sole purpose of distinguishing deep-sky objects from the
infrequent appearances of comets. It excluded many of the brightest deep-sky objects and only included objects visible
from Paris.
Moore selected 109 star clusters, nebula and galaxies to match the commonly accepted number of Messier objects
(he excluded M110.) He used his other surname, Caldwell, for the catalog name since the letter “M” was already
used for Messier. “C” became the designation for the Caldwell naming convention.
Sky & Telescope published the list in its December 1995 issue.
Amateur astronomers, after they view all of the Messier catalog, often begin working through the Caldwell catalog
which also includes objects from the Southern Hemisphere.
