Reference times from the period sources reduce TESS offsets below two standard errors for HAT-P-16 b and WASP-20 b

Do large transit timing offsets remain when the period and reference time come from the same source? We audit 153 accepted TESS sector times from SCI 29d10603-efaf-4663-862d-a9387f5e0dfc. Of 59 composite ephemerides with different period and time references, six have a complete matching source row in a frozen NASA Exoplanet Archive query. We hold each period and measured TESS time fixed. We replace the reference time and its errors with those from the period source. For HAT-P-16 b in sector 84, the offset changes from -13.788 to -0.276 minutes. For WASP-20 b in sector 107, it changes from -12.758 to +0.949 minutes. Both new offsets stay below two combined standard errors over every allowed period-time covariance, with the quoted marginal errors and independent measurement error. An independent transit fit to the same public TESS files gives offsets of -0.369 and +0.928 minutes and supports this result. Five source pairs have explicit BJD-TDB times. Two of these change from above three to below three standard errors; the other three stay below three. A sixth case, WASP-108 b, also changes below three but has an unclear BJD time scale. The other 53 mixed-reference cases lack a complete matching archive time and remain unresolved. The result tests these predictions, not orbital decay or a new planet. The package preserves the signed parent, frozen archive and FITS inputs, source records, code, figures, all selection decisions, and an independent arithmetic check.

TESS · transit timing · ephemeris · NASA Exoplanet Archive · HAT-P-16 b · WASP-20 b · data provenance · covariance