SUMMARY OF PROPOSAL 42059
PROFESSOR PETER F. MICHELSON
STANFORD UNIVERSITY
CALIFORNIA USA 94305
STANFORD
VARIAN 168

  E-mail: E7.F69@FORSYTHE.STANFORD.EDU	Tel: (415)723-3004	Fax: (415)725-6544
  Medium: 2GBDAT

Subject: X-RAY BINARIES                                              
  Title: PROBING THE MATTER DISTRIBUTION IN THE 4U1907+09 SYSTEM WITH ASCA               


Abstract:
 The massive X-ray binary pulsar 4U1907+09 appears to have a supergiant companion and
 an 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 a matter envelope in the companion's
 equatorial plane. We will test this hypothesis by obtaining four 20 ksec
 observations of 4U1907+09 distributed around the 8.38 day orbit to map out the
 hydrogen column density and iron line emission of the matter envelope. We will also
 examine how the spectra changes with the phase of the 437.5 sec pulse period in
 order to test theories of pulse profile production, as well as updating the orbital
 parameters of the system and measurements of the pulsar spin-down.

 Co-Is:
   1  MALLORY ROBERTS     	STANFORD UNIVERSITY           USA       
      MALLORY@LELAND.STANFORD.EDU	(415)327-1610
   2  LYNN COMINSKY       	SONOMA STATE UNIV.            USA       


Target Name           PRI RA        Dec        Time TC  Off GIS SIS_Cts  Obs
-------------------   --- --------  --------   ---- --  --- --- -------  ---
4U1907+09              0  287.4075    9.8269    40   Y   Y   P  2.60200   4 

REMARKS:  WE REQUEST 4 20 KSEC OBSERVATIONS WITH 1-2 DAYS IN BETWEEN SO AS TO EVENLY
          SAMPLE AN 8.38 DAY ORBIT. DATE OF OBSERVATION NOT TIME CRITICAL. IN CASE
          OF BRIGHT OUTBURST, SIS MASKING WILL BE NECESSARY.
Monitored Oservation:
          Min. Int: 84.000  Max. Int: 168.000