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

We propose to monitor the M31 core with five 23ks XMMNewton EPIC and five 20ksChandra HRCI observations equally distributed from Nov 2007 to mid Feb 2008 todetermine the light curves for short supersoft source (SSS) states of opticalnovae. SSS states with <100 d duration indicate accreting massive white dwarfs.They are proposed as SN Ia progenitors and determining their frequency is veryimportant. We will correlate detected sources with novae from optical monitoringof the same area. With a nova rate in the field of virgul25/yr and SSS states lastingfrom weeks to years we will follow light curves of many novae. Durations of thenova SSS state will allow us to constrain envelope and whitedwarf masses. Wewill also monitor time variability of virgul200 M31 centre Xray sources (mostly XRBs). truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]