Identify the physical origin of the NIRISS/AMI instrumental jitter blur

Determine which mechanism primarily causes the approximately 21 mas instrumental blur observed in JWST/NIRISS Aperture Masking Interferometry data: high-frequency vibrational modes of optical components (e.g., the secondary mirror) or electron diffusion in the H2RG detector substrate.

Background

In the linear detector stage of Amigo’s Effective Detector Model, the authors model an instrumental blur that is significantly larger than JWST’s pointing jitter. They posit two plausible causes: fast vibrational modes in the optical train or electron diffusion within the detector substrate. However, the dominant physical origin has not been established, leaving an ambiguity that could affect point spread function modeling and downstream calibration.