v0.2.0

0.2.0 - 2026-07-25

Added

• LeapSecond.expires_on, LeapSecond.expired? and
  LeapSecond.updated_through expose the expiry date and IERS bulletin that
  Leap_Second.dat states in its header. Both were previously discarded with
  the rest of the comment lines. Unlike Data.status.cache_age, which measures
  when a file was downloaded, these describe how long the data itself stays
  authoritative.
• LeapSecond.at now answers 1961-01-01 through 1972-01-01, the era when UTC
  was steered by rate adjustments rather than whole leap seconds. It returns
  those values as exact Rationals. The coefficients come from the USNO
  tai-utc.dat file and are bundled in source, since they are fixed. The
  change is additive: the pre-1972 range previously raised, so no successful
  call returns anything different. TAI.utc_to_tai and TAI.tai_to_utc gain
  the same range for free.

Changed

• Parsers::LeapSecond.parse returns a Table of entries and metadata
  instead of an array of entries. Parsers is internal; the public API is
  unaffected.
• Parsers::LeapSecond.parse no longer raises Encoding::CompatibilityError
  on a file containing invalid UTF-8. Header metadata is read on a best-effort
  basis and an unreadable data row raises ParseError as before.

Full Changelog: v0.1.1...v0.2.0

v0.1.1

0.1.1 - 2026-06-27

Changed

• Refreshed the bundled finals2000A.all snapshot from IERS. Final values now
  extend through 2026-06-25 (previously 2026-02-19) and predictions through
  2027-08-22.

v0.1.0

v0.1.0 - 2026-02-27

Initial public release.

Features

• Polar motion - PolarMotion.at returns x/y coordinates with Lagrange or linear interpolation; PolarMotion.rotation_matrix_at builds the full W rotation matrix; PolarMotion.between for daily range queries
• UT1-UTC - UT1.at with automatic UT1-TAI normalization across leap second boundaries; Bulletin B preference over Series A when available
• Celestial pole offsets - CelestialPoleOffset.at for dX/dY corrections
• Length of day - LengthOfDay.at for LOD excess
• Delta T - DeltaT.at for TT - UT1, extended back to 1800 with Espenak & Meeus polynomials
• Earth Rotation Angle - EarthRotationAngle.at per IERS Conventions 2010
• Greenwich Mean Sidereal Time - GMST.at via ERA + polynomial
• Terrestrial rotation - TerrestrialRotation.at for the R(ERA) × W matrix
• Unified EOP - EOP.at and EOP.between composing all individual parameters
• Leap seconds - LeapSecond.at for TAI-UTC lookup with binary search; LeapSecond.next_scheduled for the next known transition
• TAI utilities - TAI.utc_to_tai and TAI.tai_to_utc for UTC↔TAI conversion
• Bundled data - ships a finals2000A.all and Leap_Second.dat snapshot for out-of-the-box usage with no network calls required
• Data management - Data.update! downloads fresh files with atomic writes and redirect handling; Data.ensure_fresh! raises StaleDataError when coverage is insufficient; DataStatus reports bundled/cached/custom state
• Configuration - IERS.configure for data paths, interpolation method (:lagrange or :linear), Lagrange order, freshness thresholds, and download URLs; per-query interpolation: override on all .at methods
• Time inputs - all query methods accept Time, Date, DateTime, Modified Julian Date (float), or Julian Date (float)
• Data quality - every Entry exposes observed? and predicted? predicates via the HasDataQuality mixin; date via HasDate
• Lazy enumerators - between returns a lazy Enumerator for memory-efficient iteration over large date ranges
• Thread safety - mutex-protected lazy caching in Data and LeapSecond
• Error hierarchy - IERS::Error base with ConfigurationError, DataError, DownloadError, ParseError, OutOfRangeError, and StaleDataError