Path and time stretch models give similar fits to 33 KELT-17 b transits with a circular orbit, spherical star, fixed radius ratio, and free depths

We test two explanations for a reported KELT-17 b transit width increase. The same five public TESS sectors contain 33 accepted transits in 2021 and 2023. We use a circular orbit and spherical star. The radius ratio is fixed at 0.09166. Each event has a free depth, center, and local baseline. The path-change model gives chi squared 12924.573. The uniform time-stretch model gives 12924.305 with the same parameter count. Freeing both changes gives 12924.229. Thus the two restricted explanations give similar fits. In 600 whole-event resamples within sectors, the nominal 95 percent interval for the impact parameter change is -0.0244 to +0.0416. The two changes have a resample correlation of 0.994. One trial reaches a search bound. Extending the change bounds for that trial leaves the reported percentile endpoints unchanged. The joint half-depth width change is +0.850 minutes, with an interval of +0.309 to +1.376 minutes. The ingress change interval, -0.777 to +1.740 minutes, includes zero. Seven controls retain small chi-square differences, from 0.061 to 0.567. Exploratory fits with a free radius ratio reach the lower search bound. The event intervals hold unknown sector and epoch errors fixed. This conditional shape test does not establish orbit precession. The package preserves the original light curves, source hashes, new code, fit records, resamples, figures, and reproduction steps.

KELT-17 b · TESS · transit shape · transit duration · impact parameter · model identifiability · public astronomical data