SkySift candidate KIC 6146676: a 40.291 d transit signal in Kepler photometry

A dip of 0.22 percent repeats every 40.3 days on a star of magnitude 16.2. Ephemeris: P = 40.29081 ± 0.00015 d, T0 = BJD_TDB 2455734.3205 ± 0.0014 (epoch 19, the centre of the series), duration 3.686 +0.063/-0.072 h, depth 2,214 ± 114 ppm. Reddening: E(B-V) 0.009 (16th to 84th percentile 0.009 to 0.014) from Bayestar19 (Green et al. 2019) at 303 pc (E(B-V) unchanged at the printed precision across the distance's 16th to 84th percentiles, 300 to 307 pc), a sightline average, nearer than the map's reliable range (from 405 pc), adopted; through the Gaia DR3 law it gives E(BP-RP) 0.011 (0.011 to 0.018), A_G 0.020 (0.020 to 0.032) and A_Ks 0.003 (0.003 to 0.005), and Teff 3,666 +90/-78 K (unreddened 3,653; full column 4,657), radius 0.500 +0.015/-0.016 Rsun (unreddened 0.499; full column 0.540) and planet radius 2.5 ± 0.1 Earth radii (unreddened 2.5; full column 2.7); unreddened (E(B-V) = 0) is the earlier assumption; the 3D value is consistent with the full column (the full column, 0.674 ± 0.034 on the Schlafly and Finkbeiner 2011 scale, is an upper bound); the star sits about 39 pc above the plane, inside the dust layer, so its true reddening lies well inside the range from unreddened to the full column; the map does not constrain the dust this near on this sightline; GSP-Phot E(BP-RP) 0.27, biased for cool dwarfs (Andrae et al. 2023), is not adopted. False-alarm probability: 1 in 170. 11 of 1,998 null searches (the inverted and scrambled light curves of 999 other KBonus stars, searched without the masked pass and alias resolution) reached the signal's SDE; across the 1,579-star sweep about 9 such peaks are expected by chance, and the vetting ladder, not the SDE, separates the candidate from them. False-positive probability: TRICERATOPS 1.1.0 gives 0.073 (0.022 without a planet on an unresolved bound companion), and 0.055 (1 in 3,000 without it) with the 6 neighbours the difference images exclude removed, in none of its validation classes, which do not apply at 30-minute cadence (Giacalone et al. 2021); a four-scenario estimate without a bound-companion or diluted-planet scenario gives 0.0033, a lower bound. The pixel-excluded value (0.055, mainly STP) rests on our own evidence, the difference-image centroids; the all-neighbours value (0.073) rests on neighbour shares set by the PRF overlap rule within the catalogue's crowding budget, a bound rather than a measurement. This record is the submission pack of a transit candidate found by the SkySift engine in the KBonus Kepler Background light curves: the detrended light curve, the ephemeris and parameters with their errors, the per-event depths, the vetting metrics, the figures, the standalone dossier, a Research Note draft and the provenance of every query. What is not yet known: A season's box is cut by the stamp edge; No spectrum: the planet radius depends on the stellar radius from Gaia colour and parallax, and the map does not constrain the reddening this near; This is a candidate until follow-up confirms it.