To find and download HEASARC data in the cloud, you can use astroquery.heasarc or download our new tool, hark.
The HEASARC and NuSTAR teams are greatly saddened by the sudden passing of Katja Pottschmidt. Most recently Katja was the lead scientist for the NuSTAR Guest Observer Facility (GOF), a role she had supported for many years. During her science career she worked on many other high energy astrophysics missions and played an integral role in advancing our knowledge of the universe. She was a wonderful colleague and friend and will be keenly missed by all who knew her.
Introduction
XSPEC is a command-driven, interactive, X-ray spectral-fitting program, designed to be completely detector-independent so that it can be used for any spectrometer. XSPEC has been used to analyze data from HEAO-1 A2, Einstein Observatory, EXOSAT, Ginga, ROSAT, BBXRT, ASCA, CGRO, IUE, RXTE, Chandra, XMM-Newton, Integral/SPI, Fermi, Swift, Suzaku, NuSTAR, AstroSat, Hitomi, Insight-HXMT, NICER, IXPE, Spectr-Roentgen-Gamma, and XRISM. There are now more than 14,000 refereed papers listed on ADS which mention XSPEC.
This manual describes XSPEC v12, which is available on Linux and
MacOSX. The Python interface PyXspec is described in a
separate manual at
https://heasarc.gsfc.nasa.gov/docs/xanadu/xspec/python/html/index.html.
New users are advised to read
Chapter 2, which introduces spectral fitting and
the XSPEC approach, Chapter 3, which gives an overview of
the program commands, and Chapter 4, which contains
walkthroughs of XSPEC sessions. They should then experiment with XSPEC
and, if necessary, look up individual commands in
Chapter 5, or descriptions of the spectral models in
use, in Chapter 6.
The user interface for XSPEC, which employs a tcl scripting shell and the XSPEC parser, is described in Appendix A. The statistical methods used within XSPEC are described in Appendix B. Users interested in adding their own models can read how to do so in Appendix C. Appendix D describes the PLT plotting package which XSPEC currently uses for graphical output. Some of the tools (FTOOLS, programs, scripts) that can operate on XSPEC files are listed in Appendix E. The XSPEC model library can be linked into other programs following the instructions in Appendix F. Appendix G describes how to use your own proposal distribution for Markov Chain Monte Carlo. Appendix H includes some notes on the changes between XSPEC v11 and v12. Appendix I lists release notes for older versions of v12. Finally, Appendix J defines some commonly used XSPEC terms.
Subsections