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   PR # 21529
    MKN 501 and PKS 2005-489, observed by EXOSAT and ROSAT revealed a few
    hours flux variability correlated with spectral variations. Moreover 
    the presence of an absorption feature around ~0.5-0.6 keV probably   
    due to highly ionized gas has been detected. However the poor energy 
    resolution of the previous observations did not allow a detailed     
    analysis of the absorption feature spectral parameters. Substantially
    improved ASCA broad band X-ray spectra at high S/N will allow to     
    study in detail the countinuum spectral shape and the presence of    
    spectral features, in particular the absorptiontrough at ~0.5-0.6 keV
    & the expected iron features around ~7 keV.With 20 Ks ASCA observing 
    time a careful analysis of the correlation between flux and spectral 
   variability will also be possi
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