MIRI Bright Source Limits
Bright source limits of JWST's Mid-Infrared Instrument (MIRI) are predicted by a saturation model that uses measurements obtained during ground testing.
This article has not yet been updated to include in-flight performance.
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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.
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Table 1.MIRI imager bright source limits (for Ngroups = 5)
|Filter||Full Frame (mJy)||SUB64 subarray (mJy)|
Table 2.MIRI imager subarray bright source limits (for Ngroups = 5)
in F560W (mJy)
in F2550W (mJy)
Low-resolution spectrometer (LRS)
Medium-resolution spectrometer (MRS)
Glasse, A. et al. 2015, PASP, 127, 686
The Mid-Infrared Instrument for the James Webb Space Telescope, IX: Predicted Sensitivity
Pontoppidan, K. 2016, Proc of SPIE, 9910, 16
Pandeia: a multi-mission exposure time calculator for JWST and WFIRST