The 2024 TESS visit of TOI-6255 b agrees with its 2019–2022 clock under a stated noise model

We test the transit clock of TOI-6255 b with three public TESS visits from 2019, 2022, and 2024. The last visit was outside the TESS data used in the discovery study. We fit 289 accepted transit windows with local flux baselines and an exposure-averaged symmetric profile. A clock and shape fitted only to the first two visits predict the 2024 time. The measured difference is +79.8 seconds, with an estimated standard error of 61.8 seconds under an eight-orbit residual-block model. A joint linear clock gives a period of 0.23818256267 days. The quadratic clock gives a period derivative of +10.56 ± 8.05 milliseconds per year. Its approximate conditional 95 percent range is -7.38 to 28.50 milliseconds per year. Three visit times exactly set the three quadratic coefficients. They provide no separate quadratic goodness-of-fit test. Flux and shape controls change times by at most seven seconds. A check with the full loss curvature raises the derivative error to 9.37 milliseconds per year. Noise fits show limits of local error propagation. All tested rules permit zero period change. The discovery tidal model predicts a 2024 clock shift of only -0.043 seconds, which these data cannot test. We provide new visit clocks, a linear ephemeris with covariance, source data, hashes, code, figures, and offline instructions.

TOI-6255 b · TESS · transit timing · ephemeris · orbital decay · public data · noise model