The scaled eclipse gap of V539 Ara increased by 27.7 minutes in six TESS sectors from 2019 to 2026

We tested whether the primary-to-secondary eclipse phase of V539 Ara changed in six public TESS sectors from 2019 to 2026. We measured 76 eclipse times: 36 primary and 40 secondary eclipses. Each sector has a free local period and separate primary and secondary clock origins. The scaled eclipse gap is the measured secondary phase multiplied by a fixed 3.1690854-day period. The main fit uses simple aperture flux, a symmetric eclipse profile, and a quadratic local baseline. Its gap increased from 1.486880 day in sector 13 to 1.506135 day in sector 104. The increase is 27.73 minutes, with a conditional 95% orbit-cluster resampling interval of 26.68 to 28.78 minutes. All 11 tested flux and fit choices give increases, from 27.26 to 29.22 minutes. Eight compact-profile fits reach a parameter bound; the ten other fit choices have no such fits. A fixed-orbit control at the actual timestamps gives only 0.0063 minute of false endpoint change. A separate run reproduced all main event times and sector resample values. This work adds a uniform timing dataset that includes 2025 and 2026 data for a binary with known apsidal motion. It does not establish a new companion or a new physical precession rate. The timing intervals do not include all effects of stellar light variation or evolving eclipse shape. The package preserves the original light curves, checksums, query responses, source code, results, figures, and reproduction instructions.

V539 Ara · TESS · eclipsing binaries · eclipse timing · apsidal motion · public astronomical data · reproducible dataset