Alert Notice 363: Supernova SN 2007sr in NGC 4038

December 20, 2007: Further to CBETs #1172 (Drake et al.; Daniel W.E. Green, editor), #1173 (Naito et al.), and #1174 (Umbriaco et al.), the optical transient in NGC 4038 discussed in AAVSO Special Notice #84 has been identified as a supernova of Type Ia, and given the name SN 2007sr. Umbriaco et al. have determined the supernova is a few days past maximum light based upon spectroscopic template fitting.