|Rektascenzija||11 : 57.6 (u:m)
|Deklinacija||+53 : 23 (sto:m)
|Razdalja||55000 (*1000 sv.l.)
|Vizual. magnituda||9.8 (mag)
|Zorni kot||7x4 (loc min)
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 February 16, 1781, and by Charles Messier on March 24, 1781, together with M108 when they detected and measured M97, but M109, together with M108, were not added to the catalog until 1953, by Owen Gingerich. William Herschel has also found this galaxy independently, and cataloged it as H IV.61.
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.
The type I supernova 1956A occured in this galaxy on March 17, 1956, and
reached 12.8 mag in its maximum.