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Last modified: 4 March 2024

URL: https://cxc.cfa.harvard.edu/ciao/PSFs/chart2/index.html

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.

There are five 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.

  5. Creating an Image of the PSF: create an image from the MARX simulated event file.

[TIP]
Projecting Simulated Events and Creating the Image with simulate_psf

The results of steps 4 and 5 may be obtained by using the simulate_psf script.

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.

For technical information about the Chandra PSF, please see PSF Central.