K2, ZTF, and TESS exclude 27.43% of 70–1200 day periods for fixed 0.25 day dips of at least 40% in EPIC 204376071

We tested a fixed repeat of the known 2017 dip in EPIC 204376071, also called TIC 9855014. We used public K2 C2 and C15, ZTF release 24, and TESS Sector 91 measurements. The model requires an observed flux loss of at least 40% for 0.25 days in every cycle. The 2017 core center has an allowed offset of 0.025 days in either direction. A period is excluded only when two bright exposures from one survey are fully inside a predicted core for every allowed offset. Exact interval unions exclude 309.91 days of period length from 70 to 1200 days. This is 27.43% with a uniform period measure and 43.66% with a uniform log period measure. TESS adds 32.82 days beyond the K2 and ZTF union in this test. The lowest retained TESS SAP flux is 0.8962 of its median. A separate phase calculation agrees in 18,829 checks. The package preserves source measurements, hashes, code, figures, interval endpoints, and exposure pairs for the TESS increment. The fractions are geometric measures, not orbital probabilities. The result does not exclude events that change depth, duration, or timing, and it does not identify a planet.

EPIC 204376071 · TIC 9855014 · stellar occultation · TESS Sector 91 · K2 · ZTF DR24 · period constraints · public astronomical data