Faculty of Science (FNWI) - Anton Pannekoek Institute for Astronomy (API)
Abstract
Since the start of its current X-ray outburst on 2008 Sep 21 (ATel #1728), the accretion-powered millisecond pulsar SAX J1808.4-3658 has been observed for roughly 10 ks per day with the RXTE PCA. Coherent 401 Hz pulsations are clear throughout at an amplitude of 3-6% rms (2-16 keV). We have derived a pulse timing solution for this new outburst by phase connecting the pulsations observed during the interval MJD 54731-54739.