A detailed spectral study of 1E1048.1-5937

We propose a followup of a short GT observation of 1E1048.15937 in which significant spectral variations as a functionof the pulse phase and possible spectral lines were detected.Significant and relatively broad proton cyclotron featuresare predicted by model atmosphere calculations for magnetars.A detailed phase resolved spectroscopy of this AnomalousXray Pulsar (the one with the largest pulse fraction)can provide important information to discriminate betweenmodels based on accretion onto isolated neutron stars and thoseinvoking thermal emission from the surface of a magnetar. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]