ZTF DR24 shows fewer deep dimming nights at ZTF J0139+5245 in 2022–2025 than in 2018–2021

We tested whether deep dimming was less frequent in the later public ZTF record of the white dwarf ZTF J0139+5245. We froze two ZTF DR24 light-curve responses and checked that all 1,806 g- and r-band target rows agree. After quality cuts, 1,687 exposures give 738 nightly values from 31 May 2018 through 3 October 2025. We normalized each field and filter by its median magnitude. A deep night has at least 20% less relative flux and passes a three-error rule with an adopted 0.03 mag exposure error floor. There are 16 deep nights among 477 sampled nights in 2018–2021 and none among 261 in 2022–2025. With equal phase weights, the early and late fractions are 3.51% and 0.00% at an assumed period of 104 days, or 3.04% and 0.00% at 107.2 days. The target has a usable value on all 477 early nights and 261 of 262 late nights sampled by the nearest bright control star. Assigning the one wholly missing late target night a deep label gives at most 1/262, or 0.38%, on that control-night set. This bound does not cover gaps or missing exposures within a retained night. Separate filters, image-depth cuts, and warning-flag diagnostics preserve the decrease. Subtracting nearby-star variations gives one late deep night. The choices were made after data inspection. Deep nights in one event are related. The result describes sampled nights and does not establish an event rate, loss of all transits, or an orbit change. The package includes source queries, frozen data, code, numerical results, and figures.

white dwarf · planetary debris · ZTF J0139+5245 · ZTF DR24 · transits · public data · reproducible research