Messier 109 [SEP] time of discovery
Messier 109
Messier 109 (also known as NGC 3992) is a barred spiral galaxy exhibiting a weak inner ring structure around the central bar approximately away in the constellation Ursa Major. M109 can be seen southeast of the star Phecda (γ UMa).
History.
Messier 109 was discovered by Pierre Méchain in 1781. In 1783 Charles Messier catalogued NGC 3992 as his 109th object.
Between the 1920s through the 1950s, it was considered that Messier objects over 103 were not official, but in later years the
was published in "Sky & Telescope" in December 1995.
Moore used his other surname – Caldwell – to name the list, since the initial of "Moore" is already used for the Messier catalogue. Entries in the catalogue are designated with a "C" and the catalogue number (1 to 109).
Unlike objects in the Messier catalogue, which are listed roughly in the order of discovery by Messier and his colleagues, the Caldwell catalogue is ordered by declination, with C1 being the most northerly and