Loving ISIS - Confessions of a Former XSPEC User

Power Tools

The examples here have just really scratched the surface of the capabilities of ISIS. As described in the ISIS manual, there's lots of very useful stuff that it can do with the APEC database. There's also all sorts of 'advanced methods' for setting up data and models. For example, one can assign multiple responses to the data (e.g., multiple gratings orders for HRC-LETG data). You can combine data sets (see the .help file for the ISIS command combine_datasets - a more general way of combining data than adding their spectra and averaging there responses outside of the analysis package). The latter can be used to model sources that are very close together on a detector image, i.e., where one expects their spectra to 'overlap', etc.

Here are some other web-pages that describe and utilize advanced ISIS features and capabilities:

• TGCat - the Transmission Gratings Catalog. TGCat is a searchable archive of all Chandra Gratings observations. It provides an overview of source properties, interactive plotting, and downloads of processed, archived spectra. The analysis and plots were all generated with ISIS, and the interactive plotting uses a version of the custom ISIS plot routines found on these pages.
  
  
• aglc - A suite of S-lang routines from Dave Huenemoerder to perform timing analysis on Chandra gratings data.
  
  
• SITAR - A suite of S-lang routines to perform timing analysis, including the ability to define an averaged, binned Power Spectrum as an ISIS dataset, suitable for fitting.
  
  
• Analysis Software from Dave Huenemoerder, much of it dealing with the analysis of Chandra gratings data.
  
  
• MIT/CXC S-lang Modules - Various modules, all runnable and scriptable from ISIS, including parallelized computation of ISIS fit models across a heterogeneous network of machines, 3D visualization of data cubes, 3D spectral model definition and visualization, etc.
  
  
• Event-2D - Forward folding & comparison of 3D models with 2D event data, by Dan Dewey.
  
  
• Manfred Hanke's ISIS Page - Manfred maintains a nice set of links to useful software, including a very extensive set of utility scripts. (Note that these scripts share some of the code presented on this web site, so be careful if downloading both! S-lang will let you overwrite function definitions!) These pages also point toward a GIT repository of very useful ISIS scripts. Dig through there, and you'll find all sorts of nifty things.

Need further help and guidance? Send your questions to the ISIS users e-mail list: isis-users@space.mit.edu.