A candidate supernova in the ultraluminous galaxy IRAS 12112+0305

We report the discovery of a candidate supernova in the ultraluminous galaxy IRAS 12112+0305 during April/May 1995. This would be the first supernova discovered in an ultraluminous galaxy with L_IR > 10^12 L_sun, although supernovae have been discovered in the slightly less extreme starburst galaxy NGC 3690. If this is a supernova, our very limited observations suggest that it is a Type II.