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   52151
   AO 0235+164 (z = 0.9) is a unique BL Lac object as it is located behind
   an intervening galaxy half way between us and the BL Lac, yet is is
   sufficiently bright in X--rays to provide a "white light source" to
   study the elemental composition in that galaxy. Our previous ROSAT and
   Asca observations of this highly variable source yielded excess
   absorption in the intervening system implying abundances of about 0.5
   Solar, but the limited statistics precluded any measurement of edges
   due to individual elements. We propose to reobserve it for 20 ks
   simultaneously with STIS, to measure the elemental abundances as well
   as the dust content of the intervening system.
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