Bright source limits of JWST's Mid-Infrared Instrument (MIRI) are predicted by a saturation model that uses measurements obtained during ground testing.
JWST sensitivity update
Preliminary results from observatory commissioning indicate that system throughput is higher than pre-mission expectations, by amounts that vary with wavelength. Until detailed results are available and updated in Pandeia, results calculated by the ETC and JIST tools will underestimate S/N. An announcement will be made when the tools are updated.
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Words in bold italics are also buttons or parameters in GUI tools. Bold style represents GUI menus/ panels & data software packages.
The performance of MIRI has been measured directly at both the component and system level using the fully assembled MIRI flight model in a flight-like radiative environment with a well characterized radiometric source (Glasse et al. 2015). Results of these JWST throughput measurements have been integrated into a sensitivity model, which includes the following components: (1) background, (2) photon conversion efficiency (PCD), (3) encircled energy, and (4) detector performance (Pontoppidan 2016).
The values in the table and plots below were obtained from ETC 1.5.1. The JWST ETC assumes a safety margin when calculating when saturation occurs to account for pre-flight uncertainties in the overall responsivity and throughput of the observatory and instrument.