empyrean.query_horizons

query_horizons(names, observer, epochs, cache_dir=None)[source]

Query JPL Horizons for observer-table ephemerides.

Returns topocentric RA/Dec, range, rates, light-time, phase angle, elongation, heliocentric distance, and V-band magnitude pulled from the Horizons observer-table query.

Parameters:

  • names (Sequence[str]) – Object names / designations / SPK IDs.

  • observer (str) – MPC observatory code (e.g. "W84", "F51", "@399").

  • epochs (Epochs | ndarray[Any, dtype[double]] | Sequence[float]) – Observation epochs. Epochs table (converted to TDB internally) or a 1-D array of MJD TDB.

  • cache_dir (str | Path | bool | None) –

    • None (default): cache JSON responses under $EMPYREAN_CACHE_DIR/horizons (or ~/.empyrean/cache/horizons).

    • False: disable caching for this call.

    • explicit path: use this directory.

Return type:

Ephemeris

Returns:

Ephemeris – Predicted ephemeris from Horizons (all angles in degrees). Aberrated state, local-horizon angles, lunar elongation, sky rate, and position angle are not produced by Horizons; those columns come back as NaN.