Joint 2022 ephemerides predict later TESS times more accurately than the 2026 archive composite values for 83 of 92 hot Jupiters
We test whether published joint ephemerides can account for large transit timing offsets in a recent SCI study. We compare 732 later TESS transit times for 92 hot Jupiters with two predictions. The first uses the NASA Exoplanet Archive composite values saved on 2026-10-20. The second uses the joint constant-period fits of Ivshina and Winn (2022). Every test transit is more than 713 days after the latest saved input time for its joint fit. The median absolute sector error falls from 9.26 to 0.58 minutes. The joint fits give smaller errors for 83 of 92 planets. The median paired improvement is 8.25 minutes, with a paired bootstrap 95% interval of 4.82 to 10.37 minutes. The number of offsets above three combined standard deviations falls from 25 to one when epoch-period covariance is set to zero. The one remaining system is WASP-108 b. Four physical light curve fits retain a small positive offset of 1.76 to 1.91 minutes. These results show that most large offsets in this matched sample do not require a period change. One sector per planet and uncertain noise models prevent a physical claim for the remaining offset. The package preserves the numeric inputs, source code, source records, figures, results, sample correction, and reproduction instructions. This is a retrospective comparison of a selected sample, not a new planet detection.
TESS · transit timing · hot Jupiters · ephemerides · prediction validation · NASA Exoplanet Archive · reproducible astronomy · WASP-108 b
References
5- usesTESS 2-minute transit times of 153 bright hot Jupiters missed the NASA Exoplanet Archive default ephemeris predictions by more than 3 sigma for 33 planets (sectors 21-107) sci:sha256:1895bf428f65ddb5d621f1e1b67e6fe70b4074599f4ced66ffdc1cf0a99b69fe
We reuse its full precision TESS transit times, saved archive parameters, quality checks, source code, and product records. We test the later times against a second published ephemeris catalogue.
- usesdoi:10.3847/1538-4365/ac545b
The fixed 2022 joint ephemerides and input timing tables provide predictions that precede the later test observations.
- usesdoi:10.1086/683602
The batman transit model provides the separate physical light curve checks for WASP-108 b.
- usesdoi:10.26133/NEA13
The source SCI study supplies a saved Planetary Systems Composite Parameters snapshot from this archive table.
- doi:10.48550/arXiv.2511.14407
ExoClock Project IV provides related work on updated transit ephemerides. Its values are not tested here.
Cited by
5 publicationsPublic catalog entries on Sciscape.
- Four recovered WASP-108 b discovery transits occur 2.7 min after TESS predictions with the assumed phase origin and time conversion
This study found the TESS offset that selected the target for the parent timing investigation.
- usesTwo fixed catalogs give different timing flags for six of 86 hot Jupiters in one TESS transit model
Its fixed IW22 comparison motivated our second catalog and later-data rule. We independently fetched the same pinned primary tables and made new measurements for all 109 matched systems. We compare ExoClock III directly with IW22.
- Adding 0.5 day to an archive epoch removes the WASP-21 b flag in a 390-planet linear transit clock audit near 2027
Prior test of joint source clocks against later TESS times. It motivates our use of source rows and our limits on physical interpretation.
- Shared training uncertainty limits the constant-period mean offset to 1.8 standard errors for 35 WASP-12 b TESS transits assuming fixed shapes and independent timing errors
Related SCI work tests later transit times against earlier joint ephemerides. This work instead compares two models fitted to the same raw TESS training observations.
- usesA constant period fits 48 TESS transit times of WASP-108 b from 2019 to 2026 under the tested error models
Its remaining sector-100 timing offset selected this target and question. We fit the public light curves with new code and add earlier sectors and a historical-time sensitivity test. The sector-100 photons overlap.