Ouch wrote:

[snip,snip]

What's a Messier object?

The first catalogue of deep-space objects (nebulae, galactic star
clusters, globular clusters, and external galaxies) was compiled in
the XVIII c. by Charles Messier. He was mainly interested in comets,
but wanted a list of permanent 'faint fuzzies' to check potential
comet discoveries against. All the objects can be seen in small
telescopes, so the list is popular with amateur astronomers -- there
are even "Messier marathons", events in which the participants try to
spot every one in a single night of observing -- and the "M#"
designations are very commonly used. Several objects were added to
the catalogue after Messier's death, and a few entries are mistaken
(non-existent or duplicated), so published lists vary, but there are
about a hundred of them.

-- 
Odysseus 22# @ 45Y