XSPEC HELP

XSPEC is an interactive program to fit models to spectra. To start it
simply type "xspec". An interactive help facility is available using:

   XSPEC> help

An online manual, installation instructions, a list of known bugs, and
other helpful information can be found on the XSPEC website:

   http://xspec.gsfc.nasa.gov

Although XSPEC is primarily intended for the analysis of X-ray spectra
it can be used for data from other wavebands. The input data must be in
the standard FITS formats.  The ftool flx2xsp can be used to create
FITS files from an ascii file containing energies, fluxes, and errors.