Right Ascension	11 : 57.6 (h:m)
Declination	+53 : 23 (deg:m)
Distance	55000 (kly)
Visual Brightness	9.8 (mag)
Apparent Dimension	7x4 (arc min)
Discovered by	Pierre Mechain       1781

M109 is one of the "Theta"-like barred spirals, which appears as a "hazy spot" situated just 40' SE of the mag 2.44 star Gamma Ursae Majoris (Phad, or Phecda). It was observed by Pierre Mechain on March 12, 1781, and by Charles Messier on March 24, 1781, together with M108 when he measured M97. Messier listed the object now called "M109" under number "99" in a preliminary manuscript version of his catalog without a position, but together with M108, it was not added to the "official" Messier catalog until 1953, by Owen Gingerich. William Herschel has found this galaxy independently in April, 1789, and cataloged it as H IV.61 (incorrectly misclassifying it as a planetary nebula).

Kenneth Glyn Jones has erroneously misclassified M109 in his General Description chapter 1 as type Sb, while in the galaxy description, he correctly gives its class as SBc.

M109 is about 7-by-4 arc minutes in angular extent, and of apparent visual magnitude 9.5 or 9.6. Visually, only its bright central region together with the bar can be seen, and appear pear-shaped in smaller telescopes, "with a strong suspicion of a granular texture" (Mallas).

According to Brent Tully's Nearby Galaxies Catalog, M109 is about 55 million light years distant, as it is receding at 1142 km/sec, and a member of the Ursa Major Cloud, a giant but loose agglomeration of galaxies. Tully took individual distances from the redshift in a model taking the Virgo-centric flow into account. The distance of this galaxy, however, may be a bit smaller, as the average recession in this cloud is lower, and some part of the surplus may be peculiar velocity.