Retained 2022–2025 ZTF samples of J0139+5245 have phase gaps below 3 days for fixed periods of 100–110 days

We tested whether gaps in retained ZTF observation times can hide a fixed repeating phase interval at the known debris-transit white dwarf ZTF J0139+5245. We used public DR24 catalog data and local comparison objects. The late set has 537 retained g- and r-band exposures on 261 UTC nights from February 2022 to October 2025. We chose the first retained time per night. For every fixed period from 100 to 110 days and every phase, the largest empty interval in folded phase is below 3 days. A uniform frequency grid with an analytic cell bound gives an upper limit of 2.994922 days. A separate program evaluates all 12,902 critical periods where two phases coincide. It gives a maximum of about 2.981821 days. Separate g, r, and stricter combined sets give conservative upper bounds of 3.936875, 3.085615, and 3.504520 days. For every phase, the union of all repeated 15-day windows contains at least 22 selected nights across the late record, or 17 with stricter cuts. These bounds use no probability model for brightness errors. They apply to retained detections and do not give photometric detection completeness. An exposure audit finds flagged measurements and missing target rows. The 2022 boundary was chosen after inspection. Earlier SCI studies already report fewer late deep nights and limits for fixed triangular dips. This work adds continuous-period phase-gap bounds, an independent finite check, and a local calibration audit. It does not establish a new planet, the loss of all transits, or an orbit change. The package preserves source responses, query hashes, code, figures, results, and reproduction instructions.

ZTF J0139+5245 · white dwarfs · planetary debris · phase coverage · irregular sampling · ZTF DR24 · reproducible research