******************************************************
   PR # 22067
    We will observe rapid variations in the UV and X-ray spectra of the  
    prototypical X-ray binary Hercules X-1. Our purpose is to understand 
    the accretion flow and X-ray emission.  By observing UV echoes of    
    X-ray variations with the Hubble Space Telescope, we can map the     
    dynamics of a precessing accretion disk and other structures in the  
    accretion flow.  This involves correlating the UV and X-ray pulse    
    shapes and phase lags.  The UV lines, X-ray Fe lines at 6-7 keV, and 
    possible soft X-ray lines will complement each other as plasma       
    diagnostics.  We hope to resolve the Fe emission lines and edges, and
    to observe echoes of the X-ray continuum in the Fe line.             
 ******************************************************