Study of the pulse-phase dependent spectrum of the AXP 1RXS J170849.0-400910

Anomalous Xray pulsars are a small group of pulsars whose properties (periods, soft Xray spectra, no evidence for a binary nature) are differentfrom normal Xray pulsars. Similarities with soft gamma repeaters suggest thatthey are isolated neutron stars with an extremely high (10 ^{1415} G) magneticfield (magnetars). The source 1RXS J170849.0400910 shows clear spectralvariations as a function of pulse phase. We propose a 50 ks XMMNewtonobservation which will enable us to put contraints on the emission geometry ofthis source by studying the phasedependent variations in detail. This willlikely place significant constraints on any, and especially the magnetar, model. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]