Two Kepler-1708 b fits give positive fixed contrast coefficients with free circular planet shapes

We test whether changes in the planet transit shape remove two selected flux contrasts in Kepler-1708 b data. We use the public Q8 and Q16 Kepler light curves and the fixed planet-plus-moon minus planet curves recovered by an earlier SCI study. Each four-day window has its own six free circular planet coordinates, physical quadratic limb darkening, and quadratic baseline. The signed contrast coefficients are 0.983 and 1.171. The refitted zero-contrast models increase white-noise chi square by 14.33 and 7.54. The SAP flux checks give coefficients of 0.960 and 1.143. None of the 49 and 85 overlapping same-quarter control windows has a coefficient at or above its target value. These counts are descriptive. Both target fits approach zero impact parameter; the second also reaches a limb-darkening bound. The contrast curves were selected with the same target data and include changes in the published planet fit. These conditional fit results do not establish a moon or give a false positive probability. We preserve the archive data, recovered curves, source code, coefficient profiles, control fits, numerical checks, data provenance, and reproduction instructions.

Kepler-1708 b · exomoon · Kepler · transit · limb darkening · fixed flux contrast · nonlinear least squares · reproducible analysis