...Using a statistically robust sample across multiple filters with precise
focus values (–2.0 to +2.0 µm), we quantify: (1) focus-dependent FWHM variations of
18.7% across the operational range, following a parabolic relationship with minimum
at focus =–0.2 µm (FWHM(focus) = 1.92 + 0.031·focus2 pixels, R2 = 0.89); (2)
exceptional photometric stability with RMS variations <2.3% over decade timescales;
(3) astrometric precision of 20.3 ± 8.7 milliarcseconds, enabling detection of 0.5MJup
exoplanets at 10 pc; and (4) empirical detection limits for anomalous PSF