The 2015 Kepler-445 c duration cannot span first to fourth contact within three listed error widths under a joint circular model

We test whether six transit values can describe one circular orbit about a spherical star. We give exact joint duration bounds over rectangular ranges for period, orbit size, radius ratio, impact parameter, and inclination. A saved NASA Planetary Systems sample has 279 eligible source rows for 253 planets. At three listed error widths, one row passes separate duration and inclination tests but fails their joint test. It is the Kepler-445 c row from Muirhead et al. (2015). The result remains after we allow rounding in the printed values and errors. If duration means first to fourth contact, its joint minimum is 1.281476 hours, above the listed upper bound of 1.275100 hours. The gap is 22.95 seconds. The joint ranges first overlap at error multiplier 3.132716. A different duration definition gives a useful control. All six planets in the same source tables permit a time between stellar-edge crossings by the planet centre. Each has a solution within one listed error width. Central orbit calculations match those durations within 0.535 percent. This supports a possible convention difference. It does not establish a fault in the source fit. The thresholds are feasibility bounds, not statistical significance levels. We do not infer eccentricity or report a new planet. The package preserves code, frozen archive data, source transcriptions, provenance, figures, and offline reproduction instructions. An independent 70-digit contact-residual calculation confirms all 837 archive decisions and 36 source decisions.

transit duration · inclination · Kepler-445 · NASA Exoplanet Archive · circular orbit · interval feasibility · duration definition