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:

• Remeis Observatory ISIS scripts. The Remeis scripts are a super-set of the scripts presented here. They should be considered the definitive, most up-to-date versions of the scripts found here. So be careful if you download both! S-lang will let you overwrite function definitions! The Remeis Observatory pages point toward a GIT repository of very useful ISIS scripts. Dig through there, and you'll find all sorts of nifty things.
  
  
• 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. Again, the most up-to-date version of these scripts can be found within the Remeis Observatory ISIS scripts.
  
  

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