# Moira 5.1.1 — DE440 Historical Delta-T Repair **Release date:** 2026-07-22 **Public upgrade path:** 5.1.0 to 5.1.1 Moira 5.1.1 fixes reader-backed historical chart computation when the active planetary kernel is the content-identified JPL DE440/LE440 product. Moira's historical Delta-T source is expressed on a declared lunar tidal acceleration basis. Before evaluating a reader-backed ephemeris, the engine translates that clock product to the active kernel's admitted DE/LE basis. Version 5.1.0 admitted DE430/LE430 and DE441/LE441 but omitted DE440/LE440, so historical DE440 chart requests could raise `_EphemerisTimeBasisError` even though the kernel itself covered the requested epoch. This release explicitly admits DE440/LE440 at `-25.936 arcsec/cy²`, based on the JPL DE440/DE441 release record and the official Horizons historical Delta-T policy for that ephemeris generation. The mapping remains keyed by the SPK summary identity read from kernel content. Filenames do not establish identity, and no adjacent or unknown DE/LE release is inferred. The behavioral scope is narrow: - historical, basis-sensitive DE440 chart paths now reach TT normally; - modern direct-EOP epochs are unchanged; - DE430/LE430 and DE441/LE441 behavior is unchanged; - unknown or unadmitted kernel identities still fail closed. Regression coverage exercises content-derived DE440 identity, historical Delta-T binding, UT1-to-TT conversion, and the retained refusal for an unadmitted coherent DE/LE identity. Pushing the `v5.1.1` tag triggers the repository's GitHub Actions publication workflow, which builds the supported source distribution and platform/Python wheels and publishes them to PyPI.