The second orbital harmonic amplitude of HS Hydrae rises and falls in six TESS visits from 2019 to 2026

We test whether the remaining orbital brightness signal of HS Hydrae is stable after its eclipses disappear. We use all six mission light curves with 120-second cadence in a saved MAST target query. The visits span 2019 to early 2026. A joint fit uses time baselines and orbital harmonics. It excludes the old eclipse phases. The total second-harmonic amplitude increases by 791.5 +/- 115.8 parts per million from 2021 to 2023, or 22.25%. It then decreases by 738.8 +/- 99.2 parts per million by 2025, or 16.99%. All tested processing and fit choices preserve both directions. These three visits use the same camera and CCD. Separate half-visit fits differ by 342 to 560 parts per million across the six visits. The stated errors are conditional residual-noise errors. They exclude unknown calibration errors and uncertainty in the physical source of the signal. The total harmonic alone cannot give a stable inclination measure in these data. Surface spots, other stellar variations, and instrument response remain possible causes. We do not isolate the tidal component or reject the published orbital dynamics. The package preserves the six original files, provenance, code, figures, result tables, and instructions. A complete repeat run checks the numerical results against saved reference tables.

HS Hydrae · TESS · stellar binaries · orbital harmonics · time series · reproducible photometry