PHANTOM Candidate TIC 38699429: An 11.71815-Day Transit Signal in TESS Photometry

Status: planet candidate. A periodic transit-like signal on TIC 38699429 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 1.3 of this record. Changes in version 1.3 Version 1.3 adds three additional checks; the conclusion, the adopted values and the results of version 1.2 are unchanged: The sector-edge check (Detailed review): the transits measured one by one and compared by their distance from the edges of the data (sector starts and ends and longer gaps, where scattered light and pointing ramps are worst), now a standard part of PHANTOM's records. It finds no evidence that the depth is driven by transits near the tested boundaries; the closest group holds only five transits, so it is not a strong limit on every boundary-related bias. Odd and even transits overlaid (analysis__oddeven_1950.png, .json and .py): the profiles appear consistent in shape; their box depths differ by 2.1σ, as the vetting's comparison found, and the detailed review's fit with one Rp/Rs each gives 1.0σ (Detailed review explains why the two differ). Pixel-level views of the transit (analysis__pixels_1950_images.png and _map.png, .json and .py): new individual-sector visual diagnostics, the direct and difference images of five sectors with the Gaia DR3 stars marked, and the folded light curve of each of the central 7×7 pixels in the two sectors where the target's pixel contrasts most with the outer pixels. In all five sectors the largest positive difference-image pixel is the target's or an adjacent one; other residuals are present. The new figures provide additional individual-sector visual diagnostics; they do not replace or update version 1.2's quantitative localization results (Location of the dip), which use multi-sector combinations. The scientific conclusions and fitted results of version 1.2 are unchanged. Small changes to machine-readable derived values reflect the radius-unit conversion described below; the rounded summary values are unchanged. Also in this version: the record builder's current wording of the flux-ratio paragraph and of the TRICERATOPS inputs (as in PHANTOM's later records), the prior fit's radius quoted as 2.82 (+0.06/−0.06) with the stellar radius held fixed beside the adopted 2.81 (+0.11/−0.10) that includes it, a flattened 'dip on the target' vetting entry, and candidate.json's derived values computed with the IAU nominal solar-to-Earth radius ratio (109.076, against 109.1 before: adopted radius 2.8143 against 2.8149 R⊕, the implied mass and radial-velocity amplitude with it; the README's rounded values are unchanged). TIC: 38699429 Star: Tmag 15.27, Teff 2914 K, radius 0.166 ± 0.005 R☉, distance 57.5 pc (TIC v8) Period: 11.7181493 ± 0.0000090 d Mid-transit epoch: BJD_TDB 2459970.07015 ± 0.00065 Depth: 26,349 ± 1,247 ppm Duration: 1.346 ± 0.059 h Radius if on the target: 2.81 +0.11/−0.10 R⊕ (physical fit's Rp/Rs × the TIC stellar radius, both uncertainties); not included: in the same sectors TGLC's light curves measure the transit 9-16% deeper than TESS-SPOC's (a radius about 5-7% larger), while PHANTOM's photometry agrees with TESS-SPOC within about 4%; and the TIC's contamination ratio (0.04) is uncertain, with brighter stars 2-2.5 pixels away Transits meeting the fit's coverage criterion: 82 in TESS sectors 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 61, 62, 63, 64, 65, 66, 67, 68, 69, 88, 89, 90, 93, 94, 95, 96, 97, 98 Detection S/N: 33.7 (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.