ASCA Observations of 4U1907+09

The massive X-ray binary pulsar 4U1907+09 appears to have a supergiant companion and an X-ray orbital light curve characterized by two flares separated by about half the orbit, similar to GX301-2. The most natural explanation for these systems is that the neutron star's orbit is inclined to that of the matter envelope in the companion's equatorial plane. We have obtained four ASCA spectra distributed around the 8.38 day orbit, and have detected iron line emission for the first time from this system. We discuss the implications of this emission and of the hydrogen column density as a function of orbital phase for the matter distribution around the companion.