Messier 109 (also known as NGC 3992 or the Vacuum Cleaner Galaxy) is a barred spiral galaxy exhibiting a weak inner ring structure around the central bar approximately 67.2 ± 23 million light-years[4] away in the northern constellation Ursa Major.

M109 can be seen south-east of the star Phecda (γ UMa, Gamma Ursa Majoris).

Possibly the gas has been transported inwards by the bar, and because of the emptiness of the hole no large accretion events can have happened in the recent past.

[6][7][8][9] One supernova has been observed in M109: SN 1956A (type Ia, mag.

12.3) was discovered by H. S. Gates on 8 March 1956, using the 18-inch Schmidt telescope at the Palomar Observatory.