Right Ascension	12 : 21.9 (h:m)
Declination	+04 : 28 (deg:m)
Distance	60000 (kly)
Visual Brightness	9.7 (mag)
Apparent Dimension	6x5.5 (arc min)
Discovered by	Barnabus Oriani  May 5th, 1779

M61 was discovered by Oriani on May 5, 1779 when following the comet of that year, 6 days before Charles Messier's discovery, who had seen it on the same day as Oriani but mistaken it for the comet. Messier mistook it 2 times more until he realized that it did not move. As for a small number of others, this object was assigned an own number, H I.139, by William Herschel, who normally avoided to give own numbers to Messier's objects.

M61 is one of the larger galaxies in the Virgo cluster; its 6 arc minutes of diameter correspond to about 100,000 light years, similar to the diameter of the Milky Way galaxy. Its 10th magnitude corresponds to an absolute magnitude of -21.2.

Messier observed M61 on May 11th, 1779 " Anebula that is very faint and difficult to see. M. Messier (speaking of himself) realized it was not the comet, but a nebula that happens to lie on its path and at the same point in the sky." Charles Messier from his catalogue