Three TESS visits show no clear width trend for HAT-P-69 b in 2021–2025 under an independent visit error model

We test a linear change in the transit width of HAT-P-69 b. The primary sample has 13 complete transits from TESS sectors 34, 61, and 88 in 2021–2025. We fit a common symmetric profile with a free width, time, depth, and local baseline for each event. The model averages the flux over each exposure. The width is measured at half of the maximum loss before exposure averaging. The slope is +0.36 minutes per year. The 95% Student t interval from the three visit means is −1.75 to +2.46 minutes per year. It assumes independent normal visit errors with a common variance. An added event error floor widens the interval to −2.69 to +3.40. The event bootstrap alone gives +0.08 to +0.61, but it excludes errors shared by a visit. Two 30-minute transits from 2019 give a six-year extension. Its slope is +0.19, with a visit-based interval of −0.34 to +0.71. That interval widens to −0.69 to +1.06 with the event error floor. Template controls, a second 2019 reduction, separate profiles, and residual tests check the result. The short-cadence data show no clear linear width change under the tested model. The 2019 extension has a stronger dependence on the assumed profile. The archive supplies exact inputs, hashes, source code, event fits, figures, and run instructions.

HAT-P-69 b · TESS · transit width · transit duration variation · public data · error model