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MIRI Simulator

simulation of the LMC astrometric field with the F770W filter
MIRISim simulated observation of a star field in the Large Magellanic Cloud with MIRI’s F770W filter.

MIRISim* is a simulation package designed to help troubleshoot the data flow from the detectors to the archive for JWST’s Mid-Infrared Instrument (MIRI) using realistic simulated data. The MIRISim package incorporates several modules that simulate aspects of an observation:

  • The sky scene being observed
  • The different optical pathways through the instrument
  • The behaviour of its unique mid-infrared detectors

The simulator can generate imaging, as well as low- and medium-resolution spectroscopic data. With MIRISim, the team can create quasi-realistic data in the correct format with accurate metadata (header information), so the calibration pipeline can be tested under realistic conditions.

The simulated data produced with MIRISim can also be used to prepare for commissioning. During the 6-month period after launch, the instrument teams will use this data to test instrument operation and scientific performance and to ensure that the measurements and analysis we need to get the instrument ready for science go smoothly.

The value of simulators, such as MIRISim, goes beyond testing of calibration and data management processes. Simulated observations can also help scientists to better understand the capabilities of the instrument, prepare their own observations, and plan ahead for data analysis. Mock observations produced with MIRISim can be used for preparatory research projects ahead of the JWST launch. They can provide a benchmark for comparison with theoretical predictions, or output from astrophysical or cosmological simulations.



*MIRISim is owned and maintained by the MIRI European Consortium. Questions about MIRISim may be directed to .


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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.