*************************************************************************
   52043
   We propose to investigate the X-ray spectral properties of four
   bursters detected above 30 keV with SIGMA: GX354-0, SLX1732-304,
   KS1731-260 and A1742-294. All four sources have been poorly studied in
   the 1-10 keV band. We propose to obtain ASCA observations to constrain
   the origin of the hard X-ray emission, as required in particular for
   on-going theoretical investigations. Taking advantage of the high
   spectral resolution and extended energy coverage of ASCA, we will study
   the coupling between the cool blackbody-like radiation emitted at the
   neutron star surface and the Comptonizing corona (i.e. Compton
   cooling). This is required to understand the residual differences
   observed between black hole and neutron star systems, with respect to
   hard X-ray emission.
 *************************************************************************