A fixed window test leaves the KOI-2700 b tail to core ratio change uncertain in Kepler Q1 to Q16

We test a change in the optical tail to core ratio of KOI-2700 b. This ratio can test shape changes when the overall signal fades. We use 1,223 covered orbits in public Kepler DR25 Q1 to Q16 data. The early and late groups each contain two quarters in each spacecraft orientation. A local quadratic baseline gives mean dimming in a fixed core window and a fixed tail window. The equal quarter ratio changes from 0.2544 to 0.2149. The change is -0.0396, with an approximate conditional 95% interval of -0.1724 to +0.0607 from 10,000 draws with blocks of 20 orbit slots. All 14 planned sensitivity intervals include zero. Four main draws have a nonpositive quarter core, so ratio tails require care. A check added after inspection pools depths before division. It gives a change of -0.0304 with an interval of -0.1305 to +0.0640. A check without division also includes zero. Both measured windows fade, but these data do not resolve their relative change under the tested measuring and noise models. The result permits substantial shape change. Fading and fitted tail shortening were reported before; neither is a new discovery here. The contribution is a reproducible fixed window test and data product. The package preserves original FITS files, source records, code, all checks, figures, and offline instructions. The result does not measure physical tail length or grain properties.

KOI-2700 b · KIC 8639908 · Kepler · dust tails · transit shape · public data · block bootstrap · optical dimming