Roman Space Telescope Reference Information (PHASE B)

The optical reference information files have been updated to reflect the Phase B payload design. This is the design that was baselined for the Fall 2019 Mission Preliminary Design Review.

The Wide-Field Instrument

» Roman Wide-Field Instrument Reference Information
A compendium of basic reference information on the WFIRST Wide-Field Instrument. (January 25, 2021) View PDF | PowerPoint file


» WFIRST Observatory Reference Information
A compendium of basic information on the WFIRST Observatory. (March 1, 2021) View PDF | PowerPoint file

» The Coronagraph Instrument - Reference Information
Information here captures the instrument design elements as of the CGI Preliminary Design Review in September 2019 (December 2019) View PDF | PowerPoint file

Point-spread Functions

» Libraries of point spread functions for WFIRST WFI imaging modes have been computed with WebbPSF. A small set, computed at the centers of SCA 1 and SCA 18 are available here ( - 28MB) to illustrate the variation from the center to one corner of the field of view.

More extensive libraries, with PSFs computed at the center of each SCA and at various locations around the boundary of the FOV are also available; these have been computed with stellar spectral energy distributions for spectral types:

The following material on pupil masks and wavefront error as a function of field angle and wavelength is provided for those who compute PSFs with existing tools, such as GalSim.

» Data from version 8.5.5 of the WFIRST telescope and Wide-Field instrument model (.xlsm) Point-spread functions for the WFIRST Wide-Field Instrument (aka 'Wide Field Channel') can be computed at any wavelength and at any position in the field of view, given knowledge of the pupil function. The file gives Zernike decompositions of the wavefront error needed to perform this calculation; links to the pupil masks are given below. In addition to imaging mode, the Zernike coefficients are provided for the grism Wide-Field Spectroscopy Mode (WSM) in first order, and for a single field position in 0th and 2nd order. This file also provides a fit to distortions in WFI imaging mode (WIM), a mapping of WIM detector positions onto the sky, WFI SCA positions in the focal plane, etc.

» Explanation of Zernike coefficients (.docx) Contains descriptions of the columns in the preceding file.


» The first set of pupil images is for filters F062, F087, F129, F158, W146, and the prism. For these filters, the cold pupil mask consists only of an outer rim that blocks most rays from outside the primary mirror aperture stop. (SCAn_rim_mask.fits)

» The second set of pupil images is for filters F184, and the grism. For these filters, the cold pupil mask blocks most rays from the central baffles and the secondary mirror support tubes as well as material outside the primary mirror aperture stop. (SCAn_full_mask.fits)


» WFIRST Phase B Dispersion Fits (.xlsx) This spreadsheet provides information on the dispersion for the grism and prism.

» WFIRST Wide-Field Instrument Transmission (.xlsx) Contains the Effective area as a function of wavelength for each observing mode of the Wide-Field Instrument.

Additional information

» Observatory and instrument parameters is available at the IPAC site

WFIRST Instrument Reference Information Archive Pages

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