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   81301
   We propose to observe AB Dra, a dwarf nova (DN) with average reccurence
   time of 13 days, for 750 ks. This will be a unique opportunity to
   follow the X-ray variations through an outburst cycle of a DN with high
   time-resolution, high spectral capability of ASCA. We will see from the
   result of this observation if AB Dra is one in which the hard X-rays (>
   0.2 keV) are suppressed during outburst, and gradually decrease over a
   quiescence. Moreover, with the energy range covered with ASCA we will
   be able to constrain whether the X-ray generation mechanism changes
   over the outburst cycle. In any case, this observation is very
   important in the comparison with the DN outburst theories.
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