Local fits to 45 TESS transits preserve the 115-day wave preference in TOI-2109 b timing data with a constant-period clock and independent errors

We test whether local TESS flux reductions remove the reported transit timing wave of TOI-2109 b. Explicit coverage rules retain 45 transits in Sectors 52 and 79. We fit SAP flux with a quadratic baseline and a symmetric transit template. The median adjusted timing error is 41.69 seconds. The 42 times shared with the published table differ by 17.11 seconds RMS. Three more times are absent from that table. We replace the source TESS times and retain 66 other times, with no WASP point and no timing-error cut. For these 111 times, a constant-period clock plus one sine wave has a BIC 27.45 lower than the clock alone. The best period is 114.76 days and the amplitude is 35.54 seconds. Linear and cubic baselines and pipeline-corrected flux give BIC differences from 26.47 to 28.76. The 178-day solution has a chi-square excess of 4.82 in the primary reduction, compared with 0.079 for the published times. Controlled comparisons show that changes in the time values affect this difference. In 360 tests with shifted measured residuals, the timing-recovery error is 34.01 seconds RMS. We provide the original public TESS files, derived times, coverage decisions, code, figures and reproduction instructions. The results assume independent timing errors and no quadratic clock term. They test local TESS reduction effects and do not confirm a second planet or a unique timing period.

TOI-2109 b · TESS · transit timing · photometry · baseline sensitivity · period ambiguity · reproducibility