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
Question: can catalogue values alone find false positives among open TESS Objects of Interest (TOIs)? Method: a transit cannot be longer than a central transit on a circular orbit. Thus the period, total duration and depth of each TOI give an upper limit on the density of the transited star. We divided the TESS Input Catalog density of the host by this limit (ratio Lambda) for 6,901 of 8,151 TOIs in the ExoFOP table of 2026-10-20. We calibrated the test with the TFOPWG dispositions. Result: with Lambda > 3 at more than 3 sigma, 48 of 1,049 false positives (4.6%) and 2 of 1,372 confirmed or known planets (0.15%) fail the test. Thus 96% of the flagged resolved TOIs are false positives, against a base rate of 43%. One flagged planet is a single-transit object with a wrong catalogue period. The other is at the threshold. With Lambda > 5, no planet fails and 13 open candidates still fail. The test finds only a small part of all false positives, but this part is clean. We list 19 planet candidates and 2 ambiguous candidates that fail the test (for example TOI-1216.01, 6702.01, 6047.01 and 2522.01). For each, we give the minimum eccentricity or minimum true period that removes the conflict. Limitation: we used catalogue values and did not fit the light curves again, so a flag can also come from a wrong catalogue duration or wrong stellar parameters. A flag means that the TOI needs a check before follow-up observations. Code, input snapshot and all tables are included.
TESS · TOI · exoplanet vetting · false positives · stellar density · transit duration · eclipsing binaries · photo-eccentric effect · ExoFOP · TESS Input Catalog
References
6- usesdoi:10.26134/ExoFOP5
Source of the TOI table with periods, durations, depths, stellar parameters and TFOPWG dispositions.
- usesdoi:10.3847/1538-4365/abefe1
Describes the TOI catalogue and its dispositions.
- usesdoi:10.3847/1538-3881/ab3467
TIC v8 gives the stellar masses and radii.
- doi:10.1117/1.JATIS.1.1.014003
The TESS mission.
- usesdoi:10.1086/346105
Relation between transit shape, period and stellar density.
- doi:10.1088/0004-637X/756/2/122
Photo-eccentric effect: the same relation used to measure eccentricity.
Cited by
20 publicationsPublic catalog entries on Sciscape.
- 76 of 2,447 NASA composite rows fail circular transit geometry within three listed error widths on 21 October 2026
This prior SCI work compares a central circular duration limit with host density. We instead test internal transit geometry with listed impact parameters.
- usesTwo models from earlier data give positive fitted depths for TOI-1216.01 in TESS sectors 88–98
Its catalogue duration flag led us to select TOI-1216.01. We fit public light curves and test later data. We did not reuse its code.
- usesTESS SAP data show weaker TOI-2640 dimming in 2025 and 2026 for the 2021 shape and the SPOC crowding model
Its host-density flag also lists the target. We test the light curves without assuming that the catalogue star is the proved source.
- usesThe 2021 dip near TOI-2640.01 is weaker in TESS sectors 90 and 99 for a fixed period
The candidate duration flags supplied starting targets for the archive inspection.
- usesTESS pixel fits in 23 sectors link TOI-785.01 to the known binary OGLE-LMC-ECL-38842
The target catalog row comes from its ExoFOP snapshot through the cited follow-up study. We preserve the original source credit.
- usesA single-source model favors a northwest source for TOI-6702.01 in 23 TESS difference images
Its catalog density test selected TOI-6702.01. We test the duration and host assumption with light curves and images.
- usesThe TOI-6047.01 dip in four TESS sectors exceeds the circular transit limit for the catalog star and radius ratio at most 0.25
Supplies the catalog snapshot, initial target list, and earlier duration-density warning. We test that warning with public light curves and pixels.
- usesTESS sectors 1-107 show 8 new transits of 5 TOIs without a catalog period; if the transit times are periodic, TOI-6663.01 has 15 possible periods (35-740 d), TOI-2298.01 has 4 and TOI-3724.01 has none
We use the same circular-orbit limit from transit duration and stellar density to flag periods that need e > 0.
- 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
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 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)
Related duration-density test for TOI false positives. We give it as context for the TOI-3724.01 duration result; we do not use its flags.
- usesFixed PRF fits in TESS sectors 73 and 79 place the TOI-5775.01 flux loss toward a nearby star
The catalog density flag motivated this source-position test. We use its frozen ExoFOP table for target selection and catalog values.
- usesA fixed transit model gives different QLP and TESS-SPOC depths for TOI 2522.01 in Sector 33
This study supplies the earlier catalog duration flag and the upstream catalog snapshot.
- supportsThe 0.911-day dip in the TOI-2640 field is weaker in TESS Sector 90 than in Sectors 36 and 37 for a two-hour template
This earlier work also lists TOI-2640 as a duration outlier under circular-orbit and catalog-star assumptions. We test the recorded signal across later visits.
- usesFixed PRF fits favor a northwest source for the long TOI 6702.01 dip in 25 TESS sectors
The catalog duration flags supplied the target list. This study tests one selected target with light curves and pixels.
- usesTESS sectors 73 and 79 separate the TOI 5775 signal from a nearby 3.035-day binary
Its open-candidate density flags define the six-object starting sample. We inspect original TESS light curves and pixels for one field.
- usesFolded TESS PDC light curves retain broad dips in four of five selected duration anomalies
We reuse the frozen catalog and flagged list to select five targets before flux inspection. We add light-curve measurements and test the proposed catalog duration error for TOI 785.01. A broad PDC dip remains, so a catalog error alone does not explain that profile.
- usesSix 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
We use its target flags and preserved TOI catalog snapshot, then fit the public light curves.
- 72 of 2,453 tested NASA composite rows fail circular transit geometry within three listed error widths
This prior SCI study tests a central-transit host-density bound. Our test uses the listed impact parameter and scaled distance with finite errors.
- challengesCentral transits at apastron match all 31 flagged TOI durations without surface contact at the catalog central values
We limit the statement that the required eccentricity for TOI-785.01 is impossible. An exact central apastron orbit matches its catalog duration without surface contact. This does not test physical survival or the probability of that orbit.
- usesBox searches at constant periods found a weaker signal near TOI-2640.01 in TESS sectors 90 and 99 than in sectors 36 and 37
This study supplies the candidate list and the preserved ExoFOP catalog row used for target selection.