New in Version 10

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

• Tcl now provides the user interface. This should be mostly transparent to the user except that more options are available (see appendix D for details). There are a few changes that are required
  • exec command or command should be used instead of $ command.
  • xhistory should be used rather than history.
  • recall and reexecute have been replaced by history and !n (to reexecute command n).
  • The XCOMS environment variable no longer works as a list of directories in which to search for script files.
  • The XSPEC initialization script is called .xspecrc and must reside in the user's home directory.
  • Since the PLT commands are not yet integrated into the Tcl environment it is not possible to write a script containing iplot and then some PLT commands. Instead, use setplot com and plot.
  • The setplot command cannot be abbreviated to set but must be at least setp.
• Dynamic memory is now used. This means that
  • XSPEC now requires much less memory on start-up and the amount of memory used will depend on the sizes of the datasets and response matrices read in.
  • Most of the arbitrary limits on the sizes of files have been removed.
  • Some sections of XSPEC have been sped-up.
• There is a new, improved makefile which does incremental builds correctly. To force a complete new build use xmake full.
• The response matrix reading has been updated to use the TLMIN4 keyword in the RESPONSE extension (mainly for use with XTE HEXTE files).
• If setplot wave has been specified and an ignore or notice command is given with real numbers then these specify wavelengths in Angstrom. For setplot chan and setplot energy the real numbers represent energies in keV.
• The algorithm for the error or uncertainty command has been improved and should be faster and more reliable.
• A bug that caused incorrect estimated parameter uncertainties for the C-stat has been fixed.
• At the end of a fit run XSPEC now writes out the principal axes of the error ellipsoid. This can give some clues about which parameters are correlated.
• All parameters have units specified.
• XSPEC now automatically writes out its current state to the file xautosav.xcm. The default is to write out the state after every command. The autosave command can change the frequency of updating of xautosav.xcm or turn it off completely.
• The editmod command enables the user to add, delete, or replacement any one component in the model.
• The dummyrsp command has additional arguments which allow the creation of a virtual response matrix with perfect resolution and efficiency.
• The abund command has two new options. abund aneb uses the Anders & Ebihara (1982) relative abundances and abund file filename reads a set of relative abundances from filename.
• The extra page is no longer produced when specifying PostScript devices using the XSPEC cpd command.
• Three new plot options are available :
  • eemodel plots the model in space.
  • eeufspec plots the unfolded spectrum in space.
  • dem plots the differential emission measure distribution for the last multiple temperature model calculated.
• The slow plotting of spectra with many channels has been fixed.
• plot summary now works correctly and plot eff has wavelength as the x-axis if setplot wave is used.
• The algebraic format for specifying models is the default. It is now possible to specify additive components outside the overall multiplicative group. The algebraic format is used internally by XSPEC so in some cases the actual order of components and hence parameters will be different. A tool is available to convert v9 scripts into v10 scripts.
• The addcomp command has been modified to reflect the change in the model format.
• Table models must now be specified as e.g. atable{filename} instead of
  atable filename.
• A new type of model is available. Convolution models are generalizations of multiplicative models and allow more complicated operations than simple multiplications. A gaussian smoothing model (gsmooth) is included as an example.
• The following new models have been added and old ones improved:
  • grbm is a gamma-ray burst spectrum (after Band).
  • c6mekl, c6pmekl, c6vmekl, and c6pvmkl supersede cp6mkl and cp6vmkl.
  • laor is an emission line from a disk around a black hole.
  • plcabs is an approximation for transmission through Compton-thick matter.
  • gsmooth is a convolution model to modify the current model by a Gaussian smoothing.
  • vphabs is a photoelectric absorption with variable abundances.
  • zvphabs is a redshifted photoelectric absorption with variable abundances.
  • All mekal based models have a new parameter called switch which sets whether the model spectrum is interpolated from a table or calculated (former is faster, latter is more accurate). The interpolation option can make up to a factor of 100 difference in speed.
  • nteea, pexrav, pexriv, and tita_a have all been improved.
  • pliref, plrefl, and zplrefl have been removed since they were inaccurate. pexrav and pexriv should be used in their place.
  • mkcflow and vmcflow use the mekal rather than meka model.
  • posm is a model for positronium continuum.
• The model.dat and lmodel.dat files have been simplified and msetup made more robust. For the change to lmodel.dat see the example file in the release. lmodel.dat and the local model source files can be placed in any directory. The XSPEC make procedure uses the environment variable LMODDIR to find the directory containing local models.