We have made a series of joint spectral fits for two blank fields , the Lockman Hole and the Lynx-3A field , where a significant amount of both ASCA and ROSAT PSPC data exist after thorough screenings .
The ASCA SIS , GIS and ROSAT PSPC spectra from these fields have been fitted simultaneously .
Comparison at E > 1 keV shows general agreement within 10 % in the Lockman Hole data and a 20 - 30 \% disagreement in the Lynx-3A data , indicating remaining observation-dependent systematic problems .
In both cases , satisfactory fits have been found for the overall 0.1-10 keV spectrum with an extragalactic power-law component ( or a broken power-law component with steepening at E < 1 keV ) , a hard thermal component with plasma temperature of kT ^ { h } \approx 0.14 keV and a soft thermal component kT ^ { s } \approx 0.07 keV .