*************************************************************************
   81209
   ASCA discovery of hard X-rays from protostars represents the capability
   of X-rays to reveal the star formation and evolution. To make a further
   study, we propose the long-term observation of the Rho Oph dark cloud.
   The purposes are, (1)to determine the rotation period of the protostar,
   especially, to confirm the reappearance of the suggestive flux
   variation of about 1 day from two protostars WL6 and YLW15, (2)to
   detect as many as X-ray flares from protostars or T-Tauri stars and to
   make systematic analyses (ex. the relation between the X-ray intensity
   and the plasma temperature, difference between flare and quiescent X-
   rays).
 *************************************************************************