A magnitude 13.5 Type II supernova, 2009dd, was discovered by Giancarlo Cortini; Alessandro Dimai and Elisa Londero (Col druscié Remote Observatory Supernovae Search) on the 13th April, 2009 in the galaxy NGC 4088 in the constellation Ursa Major.
Position(2000): RA = 12h05m34s.1, Dec = +50°32'19".4
A possible magnitude 13.7 supernova was discovered on the 13th April 2009, in the intermediate spiral galaxy NGC4088 in the constellation Ursa Major. The supernova is located 2' West, 5' South from the center of the galaxy. Position(2000): RA 12 05 33.6, Dec +50 32 18