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Almost
every amateur astronomer begins to be aware of the Messier Catalog as soon
as he or she opens their first book. The novice is sure to find some
spectacular object pictured and designated by its "Messier Number" with
the universal abbreviation "M". Of the myriads of star clusters and
nebulae scattered over the sky only about 100 (perhaps 110 at most) can
claim membership to this celebrated list. However, this happens to include
most, but not quite all, of the finest of these objects observable from
mid-northern latitudes.
Charles Messier (1730-1817) was a French astronomer who developed an
intense interest in comet hunting. While he had other achievements to his
credit, this was his chief occupation during his long observing career. In
this, he was so successful that he probably observed half of the comets
known in his time. He discovered about twenty. It was to keep track of the
star clusters and nebulae which might have otherwise confused him by their
comet-like appearance, that he began to catalog and describe them. In
commenting on his catalog in later years, he frankly stated that he had
compiled it in order to aid other comet hunters. There is a slight touch
of irony in the fact that Messier's chief claim to immortality grew out of
his efforts to rid himself of a nuisance to what, he felt, was his
important life's work. As might be expected, Messier's telescopes were all
modest instruments, none of them exceeding the capacity of telescopes
amateurs can expect to own today.
Messier did not discover all the objects in his catalog and he never made
any such claim. Many of the objects were called to his attention by his
contemporaries, notably Pierre Méchain and the fact was always carefully
noted. The catalog was published in several stages as additions were made
to it, the first 45 entries being printed in 1771. In its classic form, it
contained 103 entries. Studies of Messier's papers and correspondence (Dr.
Helen Sawyer Hogg and Dr. Owen Gingerich) suggest that another four to six
objects should be added to bring the total to 110.
The prospective observer should be warned that if he follows the older
editions of the catalog, or many of the older charts, he may find nothing
in the position indicated. More recent editions have corrected these
errors but there are a few entries about which there is some doubt.
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Courtesy
John Wagoner, CLASS and Astronomical League, USA
Edward Flaspoehler, American Association of Amateur Astronomers, USA
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