Early fits with two harmonics at 14.842 hours reduce later residual variance for SBSS 1232+563 in TESS Sector 75

We test the reported 14.842-hour signal in public TESS light curves of the white dwarf SBSS 1232+563. We use raw and corrected flux at 120 s and 20 s cadence. We fix the period at the reported value. A fit with two harmonics to early Sector 75 data reduces later residual variance at 120 s cadence. The gain is 0.277% in raw flux and 0.620% in corrected flux. Later fits use only new intercepts and slopes. A search over 6 to 24 hours peaks at 14.8393 hours in both flux products. Whole-block residual-sign tests keep within-block data structure. Full sign tests with two-day blocks give search reference probabilities of 0.00390625 and 0.001953125 for two block origins. These are conditional noise checks with only nine or ten occupied blocks. They are not measured physical false-alarm rates. Shorter blocks give weaker search evidence in raw flux. We also select a period from only the first two data stretches. It gives a negative later prediction gain in raw flux and a positive gain in corrected flux. This limits claims of a precise stable clock. The result is internal validation of a known Sector 75 waveform. It does not establish a planet or a physical cause. The package contains the original FITS data, code, hashes, query responses, figures, results, and reproduction instructions.

SBSS 1232+563 · TESS · white dwarfs · time series · correlated noise · circumstellar debris · period validation