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PSF Simulation Tool

The WebbPSF package produces simulated point spread functions for JWST based on measured or budgeted optical path difference (OPD) files comprising wavefront errors in the Optical Telescope Element (OTE) and instruments.

WebbPSF provides:

Screenshot from WebbPSF Tool

  • Support for all of JWST's instruments.
  • PSF simulations for direct imaging, IFU, and coronagraphic modes, and for non-redundant aperture masking mode on NIRISS.
  • Arbitrary oversampling of output PSFs.
  • Quick calculations using optimized matrix Fourier transforms, the fast semi-analytic coronagraphy algorithm, and the FFTW3 library (optional).
  • Built-in functions for PSF evaluation such as producing radial profile plots, measuring encircled energy curves, FWHMs, etc.
  • An easy-to-use scripting interface for integration with other tools.

For the latest version of WebbPSF, and a description of its regularly increasing fidelity and scope, please refer to the links immediately below.

You can access a pre-made set of simulated point spread functions for JWST, generated with WebbPSF.

Obtaining WebbPSF

WebbPSF is written in Python and should run on any platform that supports numpy/scipy/matplotlib. About 900 MB disk space is required, mostly for the simulated OPD map library.

Installation Instructions       Release Notes

Software Documentation

Additional documentation and examples for WebbPSF are also available.

WebbPSF Documentation       Quick Start       Scripting Interface Examples

WebbPSF Feedback

WebbPSF was developed by Marshall Perrin, with contributions from other members of the Telescopes group at STScI. Please send any comments or suggestions to the JWST Help Desk.


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For technical assistance, please contact the JWST Help Desk.


The NASA James Webb Space Telescope, developed in partnership with ESA and CSA, is operated by AURA’s Space Telescope Science Institute.