NGC 3646 (also MCG 3-29-37, UGC 6376 and PGC 34836) is a magnitude +10.8 ring galaxy located 195 million light-years away in the constellation Leo.
The galaxy was discovered by German-British astronomer William Herschel using a 47.5 cm (18.7 inch) reflecting telescope at Datchet, Berkshire, on the 15th February 1784.
Right Ascension 11h 21m 43.2s, Declination +20° 10' 09"
