[astro-ph.IM]. A wavefront-sensor (WFS) prediction can select the photon measurement before detection or condition its likelihood afterward.
This matters for reflected-light spectra requiring hundreds of hours, because subtracting residual starlight cannot remove its photon noise. In a two-mode, low-occupation model, isotropically distributed leakage makes planet-mode projection—ideal single-mode injection matched to the planet—the optimal fixed single-photon measurement, including unequal aligned backgrounds and equal Poisson detector-event rates per output.
For nonzero leakage, an attainable two-output conditioned measurement is optimal and strictly more informative before differential loss.
For an isotropic background, a contrast bound holds for any distribution of recorded leakage directions: relative transmission 0.80 and relative admitted-time duty 0.90 limit the Fisher information per scheduled time to 0.81 of the fixed optimum at equal predictable-leakage and planet contrasts. Haar averaging sharpens this ceiling to 0.78.
The necessary leakage-to-planet ratios for gain are approximately 2.25 for any direction law and 3.26 for Haar directions. A concentration-model certificate identifies directional diversity sufficient to beat recalibrated fixed measurements.
Independently gated fixed-basis fallback guarantees no loss of continuum-profiled spectral information when rates and costs are known. For the Habitable Worlds Observatory, the candidate regime is predictable, directionally diverse, leakage-dominated residuals, not a general sensitivity improvement.
Slava G. Turyshev
Comments: 18 pages, 5 figures, and 5 tables
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2609.31778 [astro-ph.IM] (or arXiv:2609.31778v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2609.31778
Focus to learn more
Submission history
From: Slava G. Turyshev
[v1] Thu, 24 Sep 2026 19:43:55 UTC (1,687 KB)
https://arxiv.org/abs/2609.31778
Astrobiology,
