  The Chandra / LETG spectrum of SS Cyg in outburst shows broad (\approx 5 A)
spectral features that have been interpreted as a large number of absorption
lines on a blackbody continuum with a temperature of 250 kK (Mauche 2004). It
is most probable that this is the spectrum of the fast-rotating optically thick
boundary layer on the white dwarf surface. Here we present the results of
fitting this spectrum with high gravity hot stellar model atmospheres. An
extended set of LTE model atmospheres with solar chemical composition was
computed for this purpose. The best fit is obtained with the following
parameters: T_eff=190 kK, log g=6.2, and N_H=8 10^{19} cm^{-2}. The spectrum of
this model describes the observed spectrum in the 60--125 A range reasonably
well, but at shorter wavelengths the observed spectrum has much higher flux.
The reasons for this are discussed. The derived low surface gravity supports
the hypothesis of the fast rotating boundary layer.
