Come analyze HEASARC, IRSA, and MAST data in the cloud! The Fornax Initiative is now welcoming all interested beta users.
v12.7.0 May 2011
New features
- The primary new feature of 12.7.0 is the addition of the Python module, PyXspec v0.9 beta. PyXspec is built and installed by default on most platforms along with the regular XSPEC build, and simply requires an import xspec statement to load into Python. XSPEC can now be run from object-oriented Python scripts, or interactively from a Python shell prompt. Detailed instructions can be found in PyXspec.pdf. While most features of standard XSPEC are already supported in this beta release, some still remain to be implemented. Please let us know if any missing feature is of particular importance to you, or if you have suggestions and ideas for improvement.
- New models:
- cplinear: Piecewise linear non-physical background model for low-count spectra developed for Chandra by Patrick Broos.
- eqpair, eqtherm, compth: Paolo Coppi's hybrid hot plasma emission models.
- vvapec, bvvapec: APEC models allowing all 30 elemental abundances to vary (for use with AtomDB 2.0).
- zigm: Multiplicative model, computes the mean attenuation of the optical/UV spectrum by the intergalactic medium.
- zashift, zmshift: Convolution models for applying redshifts to additive and multiplicative models respectively.
- Also note that the default APEC model data files have been updated to AtomDB 2.0. This version of AtomDB includes contributions from more elements than earlier versions. When using the apec and vapec models these extra elements have Solar abundance by default. To change this use xset APEC_TRACE_ABUND.
- The statistic command may now be applied to individual spectra. This makes it possible to simultaneously fit spectra which require different fit statistics.
- Added the pgstat option to the statistic command. This is similar to using cstat with a background file except that the background is assumed to have Gaussian statistics (not Poisson) read from a STAT_ERR (and optionally SYS_ERR) column.
- Modified the pileup model for consistency with Sherpa and ISIS. A new parameter fracexpo is added which should be set to the FRACEXPO keyword value in the ARF.
- It is now possible to choose proportional or fixed fit deltas from the startup Xspec.init file. The initial default setting is now proportional deltas rather than fixed deltas.
- Improvements made to the output generated during a fit. The parameter names are listed at the top of columns, not just their numbers. Column alignment has been improved, and is no longer limited to a maximum width of 5 columns.
- Added reporting of the Bayesian contribution (if any) to the fit statistic output.
Enhancements previously released as patches to 12.6.0
- Initpackage now recognizes and builds files with .f03 extensions for Fortran 2003, and .f90 extensions for Fortran 90.
- Added a new fakeit option for setting the fake background exposure time.
- Added a new tclout version option for returning the XSPEC version string.
- Improved XSPEC's internal update mechanism to reduce the number of model calculations.
Bug fixes
All bug fixes to v12.6.0 released as patches a - ab are included in v12.7.0. In addition the following problems have been corrected:
- A crash occurred if tclout notice energies was performed on a spectrum containing only a dummy response with no channels.
- The 5 redundant xset options (those which merely duplicate other existing XSPEC commands) weren't passing their arguments to the command handlers correctly.
- Fit error messages were misleading for the case where the data was missing a suitable response, or when the only existing models were inactive.
- A fatal error could occur in fakeit when attempting to generate a background file while only a dummy was used for the response.
- The bayes command handler was not properly handling the case where the prior type option string was abbreviated.
- A crash occurred when flux was run in error mode and the specified energy was entirely outside the range of one or more spectra.