TESS photometry of LP 40-365 does not keep one phase at the published period in 2019–2024

We tested whether the known 8.914122-hour light signal of LP 40-365 keeps one Fourier phase. We used uniform aperture photometry from twelve public TESS sectors in 2019–2024. The series contains 51,464 retained measurements over 1684 days. Four 120-second pipeline light curves provide processing checks. The common-phase score is 5148 for eleven degrees of freedom, using conditional errors from residual blocks. In adjacent sectors 74 and 75, the phase difference is −0.15974 ± 0.01023 cycles. This equals −85.44 ± 5.47 minutes relative to the printed period. The reference period error gives only 0.000167 cycles between their mean times. Aperture, baseline, timing, and pipeline checks preserve the large phase differences. Fourier image maps place the variation near the target. Tests with added signals recover their input phases. The common-phase model also fails for the four early sectors used by the original study. Thus, we cannot establish when a change began. The result concerns the observed light pattern under this reduction. It does not measure a change in material rotation or establish a planet. We preserve reduced data, masks, source code, input provenance, fit results, and figures for inspection and reproduction.

LP 40-365 · GD 492 · TIC 198510602 · TESS · stellar rotation · phase stability · runaway stars · reproducible photometry