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astro-ph.EP · Earth and Planetary Astrophysicsastro-ph.SR · Solar and Stellar Astrophysicsastro-ph.IM · Instrumentation and Methods for Astrophysics

Eight 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)

TOI-346.01 (TIC 118327533) is a TESS planet candidate. The TOI catalog gives a period of 16.56308 +- 0.00099 d. An ephemeris audit of 205 TOIs in TESS sector 107 found that the TOI-346.01 transits were not at the catalog times. We measured eight transit times in public TESS light curves (SPOC 2-min, TESS-SPOC and QLP full-frame-image data) from 2018 to 2026. We fit one transit shape to all windows and fit the time of each transit with this shape. A linear ephemeris fits the eight times with chi2 = 14.5 for 6 degrees of freedom. All residuals are less than 3 min. The period is 16.5515573 +- 0.0000071 d, and the reference time is BJD_TDB 2461234.76653 +- 0.00083. This period is 16.6 min per orbit shorter than the catalog period. The difference is 11.6 times the catalog error. The cycle count is not ambiguous: the 2026 data alone give 16.5511 +- 0.0010 d. The catalog times agree with the 2023 transit, but they were 30 h early in 2018 and 16.9 h to 18.3 h late in 2026. At seven catalog times with full coverage, the combined depth is 586 +- 369 ppm, but the transit depth is 25,437 ppm. For November 2026 to December 2027, the catalog times are 19.4 h to 26.3 h after the new times. The new times have an error of 1.2 min. We give 26 predicted transits. The transit is grazing (impact parameter 1.22). The odd and even depths agree within 1.3 sigma. For a circular orbit, the depth at phase 0.5 is 99 +- 309 ppm. No other phase shows a dip, so the period is not P/2 or P/3. The object can be a star. An eclipsing binary with two equal stars and a period of 33.1 d is not excluded. We did no pixel-level or centroid analysis. The package contains the code, the 15 unchanged TESS files from MAST, the tables and the reproduction steps.

TESS · TOI-346 · TIC 118327533 · transit timing · ephemeris · orbital period · planet candidate · grazing transit · eclipsing binary · secondary eclipse · SPOC · QLP · TESS-SPOC · follow-up planning · TOI catalog

Admitted 2 citing publications

References

11
  1. supportsCircular-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 sci:sha256:8c14a4b6b3baa23b1015ea77ebe2a9d2757636288dd1a41e3b3cd8a8d3e5297a

    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.

  2. usesdoi:10.1117/1.JATIS.1.1.014003

    TESS mission; source of all light curves.

  3. usesdoi:10.1117/12.2233418

    SPOC pipeline; source of the 2-min PDCSAP light curves.

  4. usesdoi:10.3847/2515-5172/abc9b3

    TESS-SPOC full-frame-image light curves (sectors 2, 29, 69).

  5. usesdoi:10.3847/2515-5172/abca2e

    QLP full-frame-image light curves (sectors 2, 29, 69, 96, 104).

  6. challengesdoi:10.3847/1538-4365/abefe1

    TOI catalog. We show that the catalog ephemeris of TOI-346.01 (P = 16.56308 +- 0.00099 d) does not agree with the TESS transit times from 2018 to 2026.

  7. usesdoi:10.1086/683602

    batman transit model code.

  8. doi:10.1051/0004-6361/201629705

    TESS-band limb darkening. We use an approximate relation in Teff, not the exact tables.

  9. usesdoi:10.1051/0004-6361/202243940

    Gaia DR3 source identifier and RUWE of the star.

  10. doi:10.3847/1538-4365/ac324a

    TESS eclipsing-binary catalog. The star is not in this catalog.

  11. doi:10.48550/arXiv.2506.13459

    Breakthrough Listen technosignature search that includes TOI-346.01 as a target. It is the only paper we found that mentions this object.

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