Monitoring the 2007 periastron passage of the pulsar-binary system PSR B1259-63

Nonaccreting binary systems containing a spinpowered pulsar and a Bestarprovide us with unique opportunities to investigate the interaction between thepulsar and the stellar wind. We propose to monitor the binary system PSRB125963 with its companion Bestar SS 2883 during its periastron passage insummer 2007. This XMMNewton data will enable us to examine the shocked emissionin a window around periastron in detail and to monitor how the spectral behaviorand the flux evolves when PSR B125963 passes through periastron. Thisobservations, which require only a modest amount of observing time, togetherwith archival data taken by ASCA and XMM at other orbital angles will finallyconstrain the geometry of the Bestar disk. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]