PHANTOM Candidate TIC 238293650: A 2.19645-Day Transit Signal in TESS Photometry

Status: planet candidate. A periodic transit-like signal on TIC 238293650 found by PHANTOM (Planet Hunting Across Noisy TESS Observations and Measurements), an independent search of NASA TESS photometry. It has not been confirmed as a planet: its source star and nature are not yet established by follow-up observations (see Unresolved). Version 2.1 of this record. Changes in version 2.1 Version 2.1 brings the record up to date with PHANTOM's current procedure. The conclusion is unchanged: an unvalidated planet candidate. Repeated for this version: The detailed review, on a light curve made again from raw flux in all ten sectors and flattened with the transits masked, with the period fitted and three independent ensembles per fit (Detailed review). The radius is now taken from its physical fit with the star's density as a prior: 3.75 ± 0.16 Earth radii, with a ±0.33 systematic allowance for the depth's dependence on the epoch (version 2.0: 4.0 ± 0.4). TRICERATOPS, 12 runs in two set-ups, with and without the neighbors the difference images exclude: FPP 0.012–0.017 with every neighbor kept, NFPP below 0.001 in every run. Still at the validation threshold, not reliably below it. Two-source fits of the difference images, on the analysis package's ephemeris, for the four neighbors within 31″ bright enough to make the dip: the three at 17″, 19″ and 20″ are excluded as the source; the one 7.8″ away is disfavored (the dip on the target at 8.5σ, the neighbor's share consistent with none) but not independently excluded at a third of a pixel (Location of the dip). Version 2.0 said TESS data could not distinguish that neighbor at all. The standard sector-edge check (Detailed review), the literature (NASA ADS) and archive checks of 1 November 2026 (the VizieR imaging catalogs carried over from 24 October, CDS not answering), the stellar inputs file, a re-check of the TOI, community-TOI and published candidate lists, and the vetting table (vetting 1.19, package version 5). Retained from version 2.0, unchanged: the analyses of the sectors after 55 (2023 and 2025), made on 21–22 October, each with its own inputs: the new-sector depths and ephemeris prediction (analysis__newsectors_834, on the 2019–2021 fitted ephemeris, P = 2.1964509 d, epoch BTJD 2245.38627, 1.085-hour transit); the depth by year in one photometry (analysis__ownphot_allyears_834), the edge-transit rule (analysis__edgedepth_834, named edges_834 in version 2.0, and analysis__edges_check_834) and the sector-61 injection and background tests (analysis__sector61_834, analysis__background_834), all on the 2019–2025 refitted ephemeris (P = 2.1964515 d, epoch BTJD 2302.49434, 1.085 hours); the depth by season (analysis__seasons_834, on the 2019–2021 fitted period with the search's 0.98-hour box); and the difference images split by year (analysis__diffimg_834_split, from 21 October; its file does not record its ephemeris). These scripts ran on PHANTOM's cached light curves of that date, not on this deposit's lightcurve.csv: analysis__seasons_834.py, for one, was written for version 1.0's lightcurve.csv (the six TGLC sectors of 2019–2021, without the photometry column) and does not read this one. They record the method, and their saved results the numbers quoted. The sector-61 injection file's note expected recoveries of about 0.8–0.9 from the box estimator; the saved recoveries are 0.96–1.03. Changed in the interpretation: the two reductions' weighted means agree on the same images, so version 2.0's statement that TGLC reads about 25% deeper than PHANTOM's photometry, which compared different sectors, is withdrawn; sector 9's shallow depth is new in this version and not explained. Left out as superseded: the physical fits of 21 October and the TRICERATOPS runs of 21–22 October, which versions 1.0 and 2.0 keep. TIC: 238293650 Star: Tmag 14.22, Teff 3196 K, radius 0.331 ± 0.010 R☉, distance 91.2 pc (TIC v8) Period: 2.1964515 ± 0.0000020 d Mid-transit epoch: BJD_TDB 2459302.49434 ± 0.00083 Depth: 13,506 ± 1,014 ppm (trapezoid fit, TGLC 2019–2021) Duration: 1.085 ± 0.081 h (same fit) Radius if on the target: 3.75 +0.16/−0.16 R⊕ (the detailed review's physical fit with the star's density as a prior: its Rp/Rs × the TIC stellar radius, both uncertainties); ± 0.33 R⊕ more as a sensitivity allowance for the depth's dependence on the epoch and reduction (half the difference between TGLC's sectors 7-36, 4.0 R⊕, and PHANTOM's 61-89, 3.3 R⊕; see *Detailed review*), not a calibrated 68% interval; the fitted area ratio, (Rp/Rs)², is about 10,800 ppm: not the modeled transit depth, which limb darkening, the impact parameter and the exposure time change, and smaller than the trapezoid's depth above Transits: 48 in TESS sectors 7, 8, 9, 34, 35, 36 (TGLC; the trapezoid fit's coverage criterion) and 47 in sectors 61, 62, 88, 89 (PHANTOM's photometry; epochs within the yearly analysis's fitting windows, not the same criterion) Detection S/N: 17.1 (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.