ISIS

ISIS (Interactive Spectral Interpretation System) is designed to facilitate the interpretation and analysis of high resolution X-ray spectra. It is being developed as a programmable, interactive tool for studying the physics of X-ray spectrum formation, supporting measurement and identification of spectral features, and interaction with a database of atomic structure parameters and plasma emission models.

Features:

• Efficiently generate multi-component spectral models using the APEC/APED spectroscopy database for collisionally ionized plasmas, including user-defined line profiles.
• Automatically generate custom, multi-component APEC/APED fit-functions for specialized applications.
• Examine ionization balance tables plus data on individual emission lines and continua.
• (optional) Use new ISIS functionality with familiar XSPEC models. All XSPEC additive, multiplicative and convolution models are available, including table models and local models.
• Analyze data formatted as ASCII files or FITS Type I or Type II PHA files.
• Fit scatter data.
• Read arbitrary FITS files and columnar ASCII tables.
• Rebin your data interactively, with direct control over how uncertainties are propagated.
• Factor an RSP matrix into an ARF and a normalized RMF.
• Fit spectral models to your data either directly, or by folding models through the instrument response.
• Generate fake data for Monte-Carlo analysis of model uncertainties and for proposal planning.
• Analyze piled-up CCD spectra using the model developed by John Davis (MIT).
• Do multi-order spectral analysis (e.g. using the Chandra/LETGS) by assigning multiple instrument responses to a single dataset.
• Fit multiple data sets simultaneously, including an optional instrumental background component.
• Easily combine multiple datasets, fitting a model to the summed data.
• Define fit-parameters as arbitrary functions of other fit-parameters (including inequality constraints).
• Impose arbitrary fit-constraints by introducing user-defined penalty functions.
• Compute single-parameter confidence limits
• Generate confidence contour maps; save and re-read as FITS images; plot and overplot contours.
• Fit user-defined models coded in S-Lang, C or Fortran
• Apply user-defined fit-statistics coded in S-Lang, C or Fortran
• Apply user-defined fit-methods coded in C or Fortran
• Apply user-defined RMFs defined in software (rather than as a FITS file)
• Dynamically load C, C++, and FORTRAN code from external modules
• With the PVM module, distribute computationally expensive tasks across a network of workstations.