Bayesian Analysis of the High-Energy Tail of Sigma Gem

We present an analysis of the high-energy tail of the ASCA spectrum of the X-ray bright RSCVn star Sigma Gem. We use a recently developed method (van Dyk et al. 2000) to constrain the maximum temperature and the metal abundances on this star. We seek to verify that the metallicity is indeed sub-solar ([Fe/H]=-0.15 - -0.5) as derived from EUVE and conventional fitting of parameterized optically thin plasma radiative loss models to ASCA spectra. We also illustrate Bayesian data analysis methods including Marov chain Monte Carlo to obtain a posterior sample.