Seven ZTF J0328−1219 seasons reject one 9.8–10.1 h sinusoid under independent sign-symmetric error blocks

We test one constant sinusoid for the known debris-transit white dwarf ZTF J0328−1219 across seven ZTF seasons. We fit 896 selected public DR24 g and r measurements from August 2018 to February 2025. Each season has separate magnitude offsets and a linear trend. A model with one sine and cosine pair is compared with separate pairs in each season. Both models search the full 9.8–10.1 h range. Separate pairs improve the weighted score by 833.56 over the best shared pair. No null statistic reaches this value in 999 residual sign simulations for each of the 1, 10 and 30-day block choices. Each simulation repeats both period searches. The plus-one fraction is 0.001. These approximate tests assume independent, sign-symmetric error blocks. A follow-up test allows separate positive amplitudes but one phase. It gives a fraction of 0.006 with 30-day blocks after repeating the period and phase searches. Fixed-period checks use separate filters, airmass terms, a second harmonic, fixed secondary signals and a reused local comparison-star correction. Seasonal band searches support the known A signal in 2019 and 2024 after correction for fourteen tests. No season passes that threshold in the B band. This extends earlier work with seasonal coefficients and tests of a shared pattern. It does not establish a new planet, the first changing dips, or a change in one physical orbit. The package preserves raw data, query records, hashes, code, decisions, simulated statistics, figures and instructions for reproduction.

ZTF J0328-1219 · white dwarfs · planetary debris · ZTF DR24 · seasonal variability · phase coherence · residual sign tests · public data · reproducible research