PHANTOM Candidate TIC 257060490: A 0.98499-Day Transit Signal in TESS Photometry

Status: candidate transiting companion with a radius near Jupiter's (a giant planet, a brown dwarf or a low-mass star). A periodic transit-like signal on TIC 257060490 found by PHANTOM (Planet Hunting Across Noisy TESS Observations and Measurements), an independent search of NASA TESS photometry. If on the target, a companion with a radius near Jupiter's: a giant planet or a brown dwarf is possible, and a low-mass star or an unresolved blended configuration is not excluded; radial-velocity monitoring is needed to constrain the companion's mass and distinguish these possibilities. It has not been confirmed by follow-up observations (see Unresolved). Version 1.0 of this record. TIC: 257060490 Star: Tmag 15.45, Teff 3064 K, radius 0.285 ± 0.009 R☉, distance 120.7 pc (TIC v8) Period: 0.98499295 ± 0.0000002 d Mid-transit epoch: BJD_TDB 2459756.12315 ± 0.00013 Depth: 128,078 ± 1,636 ppm Duration: 1.02 ± 0.012 h Radius if on the target: 10.34 +0.34/−0.34 R⊕ (the detailed review's physical fit with the star's density as a prior: its Rp/Rs × the TIC stellar radius, both uncertainties); ± 0.9 R⊕ more as a sensitivity allowance for the depth's dependence on the reduction and the epoch, which are confounded here (half the difference between TGLC's sectors 14-53, 11.2 R⊕, and PHANTOM's 56-83, 9.5 R⊕; see *Detailed review*), not a calibrated 68% interval. Both assume the dip is on the target with no dilution beyond the photometry's own; the allowance does not bound dilution by an unresolved companion, errors in the stellar parameters or the transit model's assumptions Transits meeting the fit's coverage criterion: 373 in TESS sectors 14, 15, 16, 20, 21, 22, 26, 40, 41, 47, 48, 49, 53, 56, 60, 74, 75, 76, 80, 83 Detection S/N: 153.9 (PHANTOM's search) The full record, with the evidence, uncertainties, data sources, cross-matches, unresolved questions and publication history, is README.md in this deposit.