*************************************************************************
   72054
   ASCA made the first detection of the Geminga pulsar in the 2-5 keV
   band, resolving the nature of its hardest X-rays in favor of nonthermal
   emission, and discovering a complex new pulse shape at these energies.
   We now propose to make a longer observation to better characterize
   Geminga's X-ray spectrum and pulse profile in terms of their thermal
   and nonthermal components, and also to study Geminga in the 4-10 keV
   range. These data will bear upon a number of fundamental problems in
   neutron star physics including high-energy emission from magnetospheric
   accelerators, interior cooling models, the properties of magnetized
   atmospheres, polar cap heating by energetic particles, and long-term
   timing behavior. Several of these issues are discussed in the proposal.
 *************************************************************************