*xspec* -- External Fitting Program

The spectral analysis system xspec, which is part of the XANADU software originally written for analysis of EXOSAT data, provides a larger variety of spectral models than those supported in PROS. PROS format spectral data can be input into xspec using the XANADU program proscon.

Users should note that for spectral data generated in PROS 2.3 or later, the PROS program downspecrdf must be run to generate the input file to proscon. Also, the current version of proscon (v. 2.3) requires the full 256-channel pulse height spectrum for the PSPC.

Thus, in IRAF,

  xs> qpspec full=yes display=0		    # generate full 256 channels and
					    # suppress printout of spectrum
  source qpoe file: xdata$rp110590n00		
  source region descriptor: c 6940 9390 240
  background qpoe file: xdata$rp110590n00 
  bkgd region descriptor: a 6930 9390 300 600
  root name for output files [root_obs.tab, etc.]: rp90 
  xs> 

  xs> downspecrdf display=0    
  list of root names for files to convert [root_obs.tab]: rp90
  Output (pre-RDF) table file:  rp90_prdf_obs.tab
  xs> 


and at the operating system (OS) level,

  OS-prompt> proscon
   PROSCON version 2.3 
  Input file : rp90_prdf_obs.tab
  OS-prompt>

Both proscon and xspec are provided and supported by the HEASARC at GSFC. For more information, contact xanprob@legacy.gsfc.nasa.gov. Software may be obtained via anonymous ftp to legacy.gsfc.nasa.gov, in the subdirectory /software/xanadu.

At the present time (June 1994), HEASARC is developing a set of IRAF tools for translating PROS spectral data into xspec format. The task stw2pha in the caltools package of ftools v. 2.9 will convert FITS versions (generated with the STSDAS task stwfits) of the _obs.tab, _soh.tab, and _boh.tab qpsec output files into an OGIP standard FITS file, which can be read by xspec. However, the tool for generating the equivalent of the rsp file is still under development. PROS users are advised to continue using proscon until the ftools development is complete.