  ESA's Superconducting Tunnel Junction (STJ) optical photon-counting camera
(S-Cam2) incorporates an array of pixels with intrinsic energy sensitivity.
Using the spectral fitting technique common in X-ray astronomy, we fit black
bodies to nine stellar spectra, ranging from cool flare stars to hot white
dwarfs. The measured temperatures are consistent with literature values at the
expected level of accuracy based on the predicted gain stability of the
instrument. Having also demonstrated that systematic effects due to count rate
are likely to be small, we then proceed to apply the temperature determination
method to four cataclysmic variable (CV) binary systems. In three cases we
measure the temperature of the accretion stream, while in the fourth we measure
the temperature of the white dwarf. The results are discussed in the context of
existing CV results. We conclude by outlining the prospects for future versions
of S-Cam.
