New in Version 8

The following list summarizes the major changes to XSPEC since the previous edition of the user's manual.

• Multiple data group support.
• Background models.
• FITS format data and response files now are supported.
• Arf command now reads auxiliary response files (FITS).
• The following new models have been added and old ones improved:
  • The Solar abundances for the Raymond-Smith model have been changed to match those for the Meka model.
  • A cooling flow model based on Meka has been added.
  • A simple reflection model valid for energies less than 15 keV has been added.
  • An energy-independent constant model has been added. This is very useful when using multiple datagroups in the case where the only thing you want to vary is the overall normalization.
  • Two models for thermal plasmas with a distribution of temperatures have been added.
• An alias command to define one's own commands.
• luminosity and cosmo commands to calculate luminosities.
• Plotting has been overhauled. Changes include the following items:
  • Plots involving data can have an x-axis in channels, energy, or wavelength. These are set through the setplot commands. The old options no longer work.
  • Two panel plots can be produced. The top panel shows data and the bottom panel shows residuals.
  • Each spectrum is now a separate PLT vector, so the spectra can be plotted in different colors, symbols, etc.
  • There are Ef(E) versions of model plots.
• The help has been consolidated so that help command gives commands and help model gives models.
• The ml option for the command stat has been renamed cstat.
• A command (query) has been added to enable/disable the continue fitting? questions that occur occasionally.
• The diagrsp command turns the current response into a diagonal matrix.
• XANADU managers can install local models in a separate directory tree so that they can be reintegrated more easily when a new release is distributed.
• New fitting algorithms have been added.
• The gain command has been improved and now can be used to fit for the gain parameters.