Quantify the post-processing gain from residual-speckle stability

Quantify the achievable post-processing sensitivity gain for the simulated Habitable Worlds Observatory observing approach by determining how the spatio-temporal correlation structure of residual speckles affects detectability after telescope-roll observations.

Background

The paper evaluates spatially averaged raw contrast, but the authors explain that post-processing can achieve deeper effective contrasts when a dark hole is maintained over an observing sequence. The gain depends on whether residual speckles are reproducible and therefore removable, or vary rapidly in time.

Although prior studies report substantial signal-to-noise improvements, the paper does not determine the exact gain for the JWST-telemetry-based active-control approach considered here. Establishing this value would connect the predicted raw contrast to the ultimate exo-Earth detection sensitivity.

References

The gain to be expected depends on the spatio-temporal correlation structure of the residual speckles: a reproducible residual halo is easier to remove than a more rapidly varying pattern. As such, an exact gain value for this study is not straightforward to obtain, but recent studies have demonstrated signal-to-noise improvements by a factor of more than eight, for example.

— JWST telemetry combined with active coronagraphy: raw contrast predictions for exoplanet imaging with the Habitable Worlds Observatory  (2608.28322 - Pourcelot et al., 28 Aug 2026) in Conclusion