SXT_FSP is the same as HXS_FSP, but for SXT spectra, you now have the option to fit
temperatures and emission measures using more than two filters.
IDL> SXT_FSP, index, data, fit_pars
SXTBOX_FSP fits spectra to a given box, chosen by LCUR_IMAGE, for a set of
SXT images.
IDL> SXTBOX_FSP, index, data, fit_pars [, sc_par, ch_dta, sdel=sdel, $
IDL> outfile=outfile, pfile=pfile, same_bx=same_bx, boxq=boxq]