Recent Spin Rate Measurements of 4U 1907+09
  In this study, X-ray spectral and pulse timing analysis of the high mass X-ray binary (HMXB) pulsar 4U 1907+09, based on the observations with RXTE are presented. Spin rate measurements indicate a new spin-down episode with a rate close to the previous steady spin-down rate. Orbital phase resolved spectroscopy reveals that the Hydrogen column density varies through the orbit reaching to its maximum value just after periastron. A slight spectral softening with increasing luminosity is also observed. 
S. Sahiner (1), S.C. Inam (2), A. Baykal (1) ((1) METU, (2) Baskent   University)
astro-ph.HE