It is possible to perform spectral fitting on the HXT, WBS and SXT data by using several routines written by Jim McTiernan. You can fit three or more filters, and thermal and non-thermal spectra. There are programs called SXTHXT_FSP and SXTHXTBOX_FSP, which will fit combined spectra for the two instruments (SXT and HXT). See the reference manual for details on how to run the program.