*************************************************************************
   61136
   Mrk 421 provides our best opportunity to understand the high-energy
   emission of blazar jets, because it has produced the largest observed
   TeV flux. Previous multiwavelength campaigns have revealed correlated
   variability, but do not provide sufficient sampling to be able to draw
   firm conclusions about the conditions in the jet. In order to make a
   significant advance over previous observations, we propose to monitor
   Mkn 421 for 400 ksec with ASCA. During this interval, optical and TeV
   observations will be scheduled at facilities at many diverse locations
   to obtain nearly continuous light curves in all wavelengths. We expect
   that this data will allow us to perform quantitative studies of the
   conditions in the jet where the high-energy radiation is emitted.
 *************************************************************************