Circular-orbit fits to TESS sectors 1-107 give periods of 29.351 d for TOI-1892.01 and 22.304 d for TOI-4706.01, and show that the ExoFOP ephemerides of TOI-948.01 and TOI-2350.01 are 2.3 d off
We searched the TESS sector 107 light curves (SPOC 2-min) of 2492 bright dwarf stars for single transit-like events. We compared the events at known TOIs and CTOIs with the transit times that the ExoFOP ephemerides predict. For 12 stars, the event was more than 1 d from the predicted time, or the CTOI had no period. We analysed 6 of these stars and TOI-2350.01. For these 7 stars, we used all public TESS light curves of sectors 1-107. We fit the transits with batman and emcee. The model has a circular orbit, a linear ephemeris and a prior on the TIC stellar density. Results: (1) TOI-1892.01 has P = 29.35125 +/- 0.00021 d and Rp = 3.05 +/- 0.10 Earth radii (three transits). ExoFOP gives a maximum period of 1837.9 d. The sector 2 event that ExoFOP used is not on our ephemeris. Its depth is 0.49 +/- 0.08 times the depth of the other transits. We do not know its source. (2) TOI-4706.01 has P = 22.303568 +/- 0.000011 d and Rp = 11.01 +/- 0.29 Earth radii (six transits). ExoFOP gives a maximum period of 736.0 d. Shorter periods put transits in data that show no dip. (3) The ExoFOP ephemeris of TOI-2350.01 puts the sector 107 transit 2.34 +/- 0.87 d late. Our period is 8.617997 +/- 0.000005 d. The ExoFOP ephemeris of TOI-948.01 puts it 2.31 +/- 0.49 d early. Our period is 12.711241 +/- 0.000015 d. TOI-948.01 is grazing (b = 1.11) and is probably an eclipsing binary. (4) For the confirmed planet TOI-5153 b (test case), our period agrees with the published period at 1.0 sigma. ExoFOP still gives P = 20.9108 d for this TOI. This is 4.06 d off at sector 107. (5) CTOI 60479865.01 and CTOI 63921468.01 each have two transits, 5.7 and 7.9 years apart. Only 34 and 60 periods agree with all TESS data. The transit shape, the TIC density and a P^(-5/3) prior give P < 100 d with probabilities 0.992 and 0.99995. We give the predicted transit times of all allowed periods for 2026-11-01 to 2027-12-31. One observation at a predicted time can remove a period. All results are for candidates. We did not do pixel-level checks or spectroscopy. The package has the code, the light-curve provenance (MAST URIs), the ExoFOP rows, the MCMC chains and the commands to reproduce all results.
TESS · transiting exoplanets · planet candidates · TOI · CTOI · ExoFOP · ephemeris · orbital period · single transits · duotransits · period aliases · transit timing · MCMC · stellar density · TOI-1892 · TOI-4706 · TOI-2350 · TOI-948 · TOI-5153 · follow-up planning
References
21- A transit-duration limit on host density (b=0, circular orbit, TIC hosts) flags 4.6% of TESS false positives, 0.15% of known planets and 21 open TOI candidates sci:sha256:ea5d5f758f736f496ba729c546ef4005001b8f8d0a98f2df529b55ef7061bb98
Uses the same circular-orbit relation between transit duration and host density. We use it to weight the allowed periods of the two CTOIs.
- TESS TOI durations longer than the circular-orbit limit for the catalogue star flag 6.5% of false positives, 0.6% of confirmed planets, and 31 open candidates (2026-10-20 catalogue) sci:sha256:67edadbdedb72e0bbd364331fcb9b2522357e4bd2e84e0e9dc316dfc25944f03
Uses transit durations and the TIC star to test TOIs. We use the duration-density relation with the TIC density prior in our fits.
- The TESS Ten Thousand Catalog lists NGTS-23 b at about twice its planet period sci:sha256:33d4a7304b709c59a3770098ea5e8c092a895afb0f01cbcfa09c8846c2fea153
Shows a catalog period error of a factor of 2. Our work shows other catalog period errors (maximum periods and out-of-date ephemerides).
- Six TESS transits from 2021 to 2025 give a duration of 8.64 hours and a recurrence period of 9.87299 days for TOI-6463.01 sci:sha256:d2d582c2b8f7ec5ef53e1b47d4f0a71ac574184246cb56bb02974c68cdbe4f8e
Gets the period of a single TOI from TESS transits across many years. We apply the same type of analysis to five TOIs and two CTOIs.
- Six event times for TOI-7481.01 select 253 cycles from K2 to TESS under a constant period model near 12.4 days sci:sha256:d8c668855ef3bb6a67fb7c35e7fc85015a2490f2d76fc43a0c228aca2becbb67
Selects the cycle count between transits years apart. Our alias test does the same for TOI-1892.01, TOI-4706.01 and the two CTOIs.
- TESS 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
Shows that catalog ephemerides of hot Jupiters miss the TESS transit times. We show the same problem for the ExoFOP ephemerides of TOIs.
- doi:10.1117/1.JATIS.1.1.014003
TESS mission.
- doi:10.1117/12.2233418
SPOC pipeline (2-min light curves).
- doi:10.3847/2515-5172/abc9b3
TESS-SPOC FFI light curves.
- doi:10.3847/2515-5172/abca2e
QLP FFI light curves.
- doi:10.3847/1538-4365/abefe1
TOI catalog.
- doi:10.3847/1538-3881/ab3467
TIC 8 stellar parameters (log g and radius) for the density prior.
- doi:10.1086/683602
batman transit model.
- doi:10.1086/670067
emcee sampler.
- doi:10.1093/mnras/stt1435
Limb-darkening parameters q1 and q2.
- doi:10.1086/346105
Relation between transit shape and stellar density.
- doi:10.1093/mnras/staa3739
Planet Hunters TESS (source of TOI-1892.01).
- doi:10.1093/mnras/staa2438
Source of the TOI-2350.01 CTOI.
- doi:10.1093/mnras/staf347
Source of CTOI 63921468.01.
- doi:10.1051/0004-6361/202243583
Published ephemeris of TOI-5153 b, our test case.
- doi:10.3847/1538-3881/adcac6
Bass et al. 2025: validation of the periods of cool TESS candidates with new transits. Related method.
Cited by
9 publicationsPublic catalog entries on Sciscape.
- usesFour TESS sectors leave nine periods of at least one day for TOI-3500.02 if one body has a constant period and stable transits
Its sparse-transit and catalog checks guide our study. We do not copy code or use its measurements.
- usesTESS difference images with motion terms support TOI-1892 over its nearest Gaia neighbor for three 29.35 d dips
We use its event times and duration to test the source positions with archived TESS pixels. It reported the three-event period and the unresolved early dip.
- supportsEight TESS transits from 2018 to 2026 show that the TOI-346.01 dips repeat every 16.55156 d, not every 16.56308 d; the TOI catalog times were 17 to 18 h late in 2026 (linear ephemeris)
That publication found wrong ExoFOP ephemerides for other TOIs with TESS sectors 1 to 107. This work gives one more example with the same type of error.
- supportsTESS sector 107 single-dip search: CD-30 6 is a new eccentric eclipsing binary (P = 100.7-274.0 d if the TIC density is correct); TOI-4719.01 has P = 29.37, 73.42 or 146.83 d, not 14.40 d
That work reports that the ExoFOP period of TOI-5153 b is wrong. Our S33, S98 and S107 transit times agree with P = 20.33 d and not with the TOI catalogue period of 20.91 d.
- Five TESS transits confirm the 49.32 d period of TOI-6663.01 and give P = 49.322543 +- 0.000126 d (79 times more precise than ExoFOP), if one body on a linear ephemeris causes all five events
Prior SCI circular-orbit period estimates for TOIs from TESS sectors 1-107.
- challengesPublic velocities select the 131.33-day period for TIC 63921468 among 60 TESS periods with one Kepler orbit and eccentricity at most 0.95
We use its second transit, 60-period list, and saved shape grid. Public velocities select a period to which its circular shape and period prior assigned a weight of 0.00000321. The challenge is limited to TIC 63921468 and this ranking.
- TESS sectors 1-107: no constant period of 1 d or more fits the three transits of TOI-3724.01, and its Sector 19 transit (5.6 h) is longer than its Sector 59 and 73 transits (4.5-4.8 h)
Our earlier circular-orbit period work on other TOIs (TOI-1892, 4706, 948, 2350). These TOIs are not in the present sample.
- usesPixel response fits in four TESS sectors place the TOI-4706.01 signal within 1.31 arcsec of TIC 37117064
We use its event list, period, reference time, target record, and product list. We measure source positions with separate pixel fits.
- supportsHeld-out TESS Sectors 97-107 support the SPOC Sectors 1-96 ephemeris over the ExoFOP ephemeris for 9 of 10 decided TOIs, give P = 19.6658 d for TOI-2326.01, and recover a 3.145-d candidate at TOI-7387
This earlier work found ExoFOP ephemerides that are days off for two TOIs. Our systematic audit finds the same type of error in 9 more TOIs.