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   51157
   Mkn421 is brightest in TeV energy among three extra galactic objects so
   far detected. From the previous ASCA observations, X-ray emission was
   proved to have a tight connection with TeV emission. Because of the
   brightness and the fast time variabity at X-ray region, Mkn 421 is one
   of the best AGN for the study of the evolution of the synchrotron
   spectrum with ASCA. In this campaign, we add VLBI observation by VSOP
   (5, 22GHz) and from Ground (15GHz) to reveal the structure and dynamics
   of the core of jet with resolution of 0.04pc. The multiband spectrum
   from Radio-Optical-UV-Xray and GeV/TeV gamma-rays together with VLBI
   images provides very important clue to understand the emission from
   Blazar, in which electrons are accelerated to very high energy (in the
   jet).
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