HCI NIRISS Limiting Contrast
Treatment of limiting contrast (Climit) is based on current information about telescope aberrations and the expected performance of JWST NIRISS AMI.
Limiting-contrast, Climit(s), is the companion-to-host flux ratio of the minimum detectable companion. It is the detection limit and the best that can be done.
The article HCI Contrast Considerations provides a general treatment of "contrast" (C), including Climit(s).
Climit(s) is a function of essentially everything related to high-contrast imaging (HCI): myriad eclectic technical factors and procedures, end-to-end. Figure 1 shows the estimated limiting contrast ratio for a 3-sigma detection of a faint companion near a bright host star as a function of their apparent separation (s) in mas, as measured from in-flight data during JWST commissioning (Sivaramakrishnan et al. 2022). If the user's operating point (s, Cflux) lies above a color curve, that source is detectable. Users may be able to extrapolate estimates of Climit(s) using the Exposure Time Calculator (ETC) and other proposal tools.
Sivaramakrishnan, A., Tuthill, P., Lloyd, J. P., et al., 2022, arXiv:2210.17434
The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope – IV. Aperture Masking Interferometry.