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   72158
   We propose to study the hard X-ray spectrum of three high redshift
   quasars all of which are part of a VLB monitoring campaign. This makes
   these sources ideal for investigating the inverse Compton (IC) process
   in quasars. Previous studies have been hampered by the lack of
   contemporaneous observations, despite the fact that intensity, spectral
   and morphological variability is common in these objects. The proposed
   observations will allow us to apply IC models and determine the
   physical parameters of the jet. Monitoring of the X-ray flux and
   spectral variability may also allow us to determine if different sites
   are involved in the production of X-rays or what the physical
   conditions are during such violent events as the ejection of new
   superluminal radio components.
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