The 2026-10-21 GJ 436 b default archive period and epoch predict 14 TESS transits 34.6 to 41.4 minutes early as a linear clock

We tested the GJ 436 b default row in a saved NASA Exoplanet Archive Planetary Systems response from 2026-10-21. Its period is 2.64388312 d and its transit epoch is 2454510.80162 BJD TDB. The cited source gives these values in different model contexts. The period matches Table 3 of Maciejewski et al. (2014), a two-planet dynamical model at JD 2455959. The epoch matches Table 2, whose linear transit period is 2.64389754 d. The two periods differ by 1.245888 seconds per orbit. We measured 14 transits in public TESS sectors 22 and 49 with independent event times and a shared symmetric profile. If the default pair is used as one linear clock, it predicts all measured transits 34.6 to 41.4 minutes early. The Table 2 clock is within 1.4 minutes of every time from the main fit. Six model controls change times by at most 0.64 minutes. All 70 injected timing shifts are recovered within 53 seconds. This study adds a source table audit and a measured timing test to an existing SCI prediction-conflict flag. Precise published clocks and analyses of these TESS sectors already exist. The result concerns direct linear use of the saved default pair. It does not test the full source dynamical model or establish an orbit change. We provide unchanged input files, provenance, all event decisions and times, model and noise checks, figures, and code for offline reproduction.

GJ 436 b · transit timing · ephemerides · TESS · NASA Exoplanet Archive · source context · reproducible astronomy