pleiades-data 0.5.6

Packaged offline ephemeris data (precomputed positions for the Sun, the Moon, Mercury through Pluto, derived from JPL public-domain ephemerides) and its EphemerisBackend for the pleiades astrology workspace.
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# pleiades-data

[![crates.io](https://img.shields.io/crates/v/pleiades-data.svg)](https://crates.io/crates/pleiades-data)
[![docs.rs](https://img.shields.io/docsrs/pleiades-data)](https://docs.rs/pleiades-data)
[![License: MIT OR Apache-2.0](https://img.shields.io/badge/license-MIT%20OR%20Apache--2.0-blue.svg)](#license)

Packaged offline ephemeris data (precomputed positions for the Sun, the Moon,
Mercury through Pluto, derived from JPL public-domain ephemerides) and its
`EphemerisBackend` for the
[pleiades](https://github.com/rahulmutt/pleiades) astrology workspace.

The crate ships a compressed artifact covering 1900-01-01 through 2100-01-01,
regenerated from the checked-in JPL reference snapshot and validated against a
deterministic binary fixture. The backend serves the Sun, the Moon and Mercury
through Pluto, and falls back to other providers when callers request bodies
outside the packaged slice.

The artifact also carries segments for `asteroid:433-Eros`, fitted to 17
reference rows. They are not served: outside those rows the fit is wrong by
tens of degrees. `PackagedDataBackend` reports the body unsupported, and
`packaged_lookup` refuses it too. Enable the
`packaged-artifact-path` feature to load an explicit artifact file for larger
or externally distributed packaged datasets.

## Quick start

```rust
use pleiades_backend::{CelestialBody, Instant, JulianDay, TimeScale};
use pleiades_data::{packaged_backend, packaged_lookup};

let _backend = packaged_backend();
let instant = Instant::new(JulianDay::from_days(2_451_545.0), TimeScale::Tt);
let sun = packaged_lookup(&CelestialBody::Sun, instant)
    .expect("Sun should be in the packaged artifact");
assert!(sun.distance_au.is_some());
```

Besides the packaged bodies, the backend serves six derived lunar points: the
osculating `TrueNode`, `TrueApogee` and `TruePerigee` (from the packaged Moon
state) and the mean `MeanNode`, `MeanApogee` and `MeanPerigee` (from the mean
lunar elements in `pleiades-apsides`). The mean apogee and perigee are the
points on the inclined mean orbit, as Swiss Ephemeris reports `SE_MEAN_APOG`.
All six are served only inside the packaged window.

## Status

Experimental, pre-1.0: breaking changes can land in any minor release. This backend returns mean
geometric coordinates and rejects apparent requests; the chart layer in
`pleiades-core` and the event engines in `pleiades-events` apply apparent
place on top of it. See the
[workspace README](https://github.com/rahulmutt/pleiades#readme) for the full
maturity posture.

## License

MIT OR Apache-2.0