starcat 0.2.0

Command-line astrological ephemeris: Compute Natal Charts
starcat-0.2.0 is not a library.

Starcat

Crates.io License

A fast, modern ephemeris reader that turns a civil date + location into a complete chart-of-the-moment in one shot.

What it does

Given a date, time, calendar, and zone (or LMT longitude), starcat compute emits:

  • Tropical or Sidereal ecliptic-of-date apparent positions — longitude, latitude, distance, daily speed, retrograde flag and more.
  • Geocentric, topocentric , or heliocentric frames.
  • The chart axes — Ac/Ds, Mc/Ic, Vx/Ax, Nn/Sn, Lil/Pri — with selectable mean-vs-true modes for nodes and Lilith.
  • Five house systems in one call: Whole Sign, Equal-from-Asc, Placidus, Regiomontanus, Porphyry.
  • Hellenistic sect and the eight Hermetic lots (Fortune, Spirit, Exaltation, Necessity, Eros, Courage, Victory, Nemesis).
  • Output as human-readable text, JSON (--json), or an opt-in TUI page (--page, feature-gated).

Coordinates render in --dd, --dms, --ddm, --dm, or --d. The JSON shape includes a placements wrapper with calculated_at, daily-motion floats at 8dp, and whole-sign cusps as exact multiples of 30°.

Why it exists

starcat the reference implementation of pericynthion. Suitable for quick chart lookups, pipelines, batch backtesting, or wiring into other tools.

How it works

starcat is a thin CLI shell over pericynthion. The binary does three jobs:

  1. Parse and validate input. Date/time parsing, calendar selection (Julian, Gregorian, or auto-detect at 1582-10-15), longitude/latitude parsing in DD/DMS/DDM, JPL data resolution (--jpl-data → --jpl-file+--jpl-header → $STARCAT_JPL_DATA), and disambiguation of the LMT-vs-UTC-offset workflows.
  2. Drive the library. Convert civil time → JD UT → JD TT, open the ephemeris, and call pericynthion::coords::apparent::apparent_ecliptic_position (or its topocentric/heliocentric siblings) once per requested body, plus the angle, node, Lilith, lots, and house-cusp routines.
  3. Serialize. Format coordinates in the requested style and emit text, JSON, or the page renderer.

The default build has a minimal dependency tree (clap, anyhow, serde); the page feature pulls in tabled for the TUI table. Integration tests live in tests/cli_compute.rs and exercise the full pipeline against reference charts when STARCAT_JPL_DATA is set, skipping cleanly when it isn't.