Type-Ia Supernova SN 1995D in NGC 2962: Optical V, R, and I Band Photometry and Spectra

Optical light curves in the V, R, and I bands, starting 10 days before the maximum light, and the optical spectra near to the V maximum phase of supernova SN 1995D in NGC 2962 are presented. The spectra taken near to the optical maximum are similar to the prototypical type-la supernova SN 1981B, and show no trace of the interstellar Nal D line. The expansion velocity at the maximum phase was 10000 ± 200 km s^-1. The supernova reached maximum light in the ^I band about four days earlier than in the V band. A distinct secondary peak is observed in the / band about 30 days after the V maximum. This secondary peak occurred about one week delayed from the published template light curve. A clear shoulder is detected in the R band light curve corresponding to the secondary peak in the I band. The initial rate of decline is slow [Δm15 (V) = 0.66 mag], and it is suggested that the supernova belongs to a group of the intrinsically brightest type-la supernovae. From the initial declining rate in the V band, we estimated the absolute magnitude M^v to be −18.8 ± 0.3 mag, and the distance modulus of the parent galaxy (NGC 2962) to be 32.2 ± 0.3 mag.