SN 1999E: another piece in the supernova-gamma-ray burst connection puzzle

Detailed optical and near-infrared observations of supernova (SN) 1999E have confirmed early suggestions that this supernova was indeed a twin of the peculiar type II SN 1997cy: it was exceptionally luminous and had evolved slowly, and the line profiles had narrow peaks and broad wings, indicating interaction with the circumstellar material. Nevertheless, the most intriguing characteristic was that, in analogy to SN 1997cy, it exploded at a position consistent in time and location with a BATSE event (GRB 980910). The a posteriori probability that the only two SNe with such an optical appearance are associated with two different BATSE gamma-ray bursts (GRBs) is only 0.2 per cent. This raises the possibility that some GRBs are associated with H-rich SNe.