  We report on a BeppoSAX Low-Energy Concentrator Spectrometer (LECS)
observation of the super-soft source (SSS) CAL83. The X-ray emission in SSS is
believed to arise from nuclear burning of accreted material on the surface of a
white dwarf (WD). The LECS spectrum of CAL83 can be well fit by both absorbed
blackbody and WD atmosphere models. If the absorption is constrained to be
equal to the value derived from Hubble Space Telescope measurements, then the
best-fit blackbody temperature is 46.4 +/- 1.4 eV while a Non Local Thermal
Equilibrium (NLTE) WD atmosphere model gives a lower temperature of 32.6 +/-
0.7 eV. In contrast to CAL87, there are no strong absorption edges visible in
the X-ray spectrum with a 68% confidence upper limit of 2.3 to the optical
depth of a Cvi edge at 0.49 keV predicted by WD atmosphere models. The
luminosity and radius derived from the NLTE fit are consistent with the values
predicted for stable nuclear burning on the surface of a ~0.9-1.0 solar mass
WD.
