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    PR # 32068                                                                   
     We propose pulse and orbital phase-resolved spectroscopy of the             
     binary X-ray pulsar Cen X-3 outside of X-ray eclipse. Previous              
     observations show that several FeK lines are present; a 6.4 keV line        
     emitted from a region within 1 lt-sec of the neutron star and lines         
     at 6.7 and 6.9 keV probably emitted from over much of the binary            
     system. At least one of the lines is modulated at the 4.8 sec pulse         
     period, but it is not possible to tell which one.  Using the SIS to         
     observe from orbital phase 0.2-0.8 it will be possible to determine         
     which lines are modulated and map out the effects of the stellar wind       
     structure and ionization in the binary system, and physically locate        
     the sites of the X-ray emission components in a massive X-ray binary        
    for the first time.                                                          
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