NGC 819NGC 819 is a spiral galaxy approximately 302 million light-years away from Earth in the constellation of Triangulum. It forms a visual pair with the galaxy NGC 816 5.7' WNW.DiscoveryNGC 819 was discovered by German astronomer Heinrich Louis d'Arrest on September 20, 1865 with the 11-inch refractor at Copenhagen. Édouard Stephan independently found the galaxy again on September 15, 1871 with the 31" reflector at Marseille Observatory.SupernovaeThree supernovae have been observed in NGC 819:SN 2007hb was discovered by Nearby Supernova Factory on August 24, 2007. SN 2007hb had a magnitude of about 19.5 and was located at RA 02h08m34.0s, DEC +29d14m14s, J2000.0. It was classified as a Type Ib/c supernova.SN 2016hkn was discovered by Fabio Briganti on October 22, 2016. SN 2014bu had a magnitude of about 17.2 and was located at RA 02h08m34.2s, DEC +29d14m11s, J2000.0. It was classified as a Type II supernova.SN 2020mbe was discovered by Gaia Photometric Science Alerts on January 10, 2020.