Resolving short supersoft source states of optical novae in the core of M31

We propose to continue the monitoring of the M31 core with five 18.4ks XMMEPIC and five 20ks Chandra HRCI observations equally distributed from Nov 2009 to mid Feb2010 to determine additional light curves for short supersoft source(SSS) states of optical novae. SSS states with <100d duration indicate accretingmassive white dwarfs. They are proposed as SNIa progenitors. Determining theirfrequency is very important. We will correlate detected sources with novae fromoptical monitoring. With a nova rate in the field of virgul25/yr and SSS states lasting from weeks to years we will follow light curves of many novae. Durations ofthe nova SSS state will allow us to constrain envelope and white dwarf masses. We also will monitor time variability of virgul200 M31 Xray sources (mostly XRBs). truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]