Nainital microlensing survey - long term photometric study of two novae in M31

Abstract

Two classical novae were detected in the disk of M 31. The photometric observations were taken in Cousins R and I bands during the four year Naini Tal Microlensing Survey which was being carried out during 1998–2002 with the aim of detecting microlensing events in the direction of M 31. The first nova, NMS-1, which had an outburst in 2000 and was monitored before the outburst as well as after, showed an R-magnitude of 17.2 on 2000 October 20, and a fast decline of 0.11 mag/day. For the second nova NMS-2, outburst at peak was not detected; however, this nova was observed during the declining phase in 2001. The rate of decline of NMS-2 suggests that either it was a slow nova or we started monitoring it at late phase of its outburst. In the follow-up observations which were carried out from 2-m Hanle telescope in 2004- 2005, we find that both the novae have reached their pre–outburst level flux, though the Rc-Ic color could be slightly different.