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Last modified: 2 July 2014


Chandra Ray Tracer (ChaRT)

The Chandra Ray Tracer (ChaRT) simulates the best available point spread function (PSF) for a point source at any off-axis angle and for any energy or spectrum. Technical details are available from the About ChaRT page.


It is important to read the caveats before running ChaRT and using the resulting PSF simulations in analysis. In particular, users whose science depends on subpixel resolution must be aware that the current version of ChaRT cannot be used with MARX to simulate the EDSER subpixel algorithm.

There are four steps to using ChaRT:

  1. Prepare to run ChaRT: determine the input parameters for the PSF raytrace.

  2. Run ChaRT: run the raytrace simulation.

  3. Retrieve ray file: obtain the ChaRT rays via FTP.

  4. Create an event file: project the rays onto the detector plane using MARX.

If you need to run multiple ray traces, you should consider installing SAOTrace and running the traces locally.

Citing ChaRT in a Publication

If you are writing a paper and would like to cite ChaRT, we recommend the following paper:

ChaRT: The Chandra Ray Tracer
C. Carter, et al.
ADASS XII ASP Conference Series, Vol. 295, 2003, p.477

The specific version of CIAO and CALDB (if applicable) used for the analysis should be mentioned as well.

Last modified: 2 July 2014
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