JPL Moshier Ephemeris Python

Pure Python ctypes runtime FFI binding for the project-owned JPL Moshier Ephemeris C library.

This package wraps the native jme_* API directly. It is intended to be a true raw I/O surface: no recalculation, no normalization, no rounding, no reshaping, no dropped buffers, and no hidden status conversion.

Contract

• Primary public functions: jme_*
• Primary public constants: JME_*
• Current wrapper target: all 204 public jme_* functions tracked by the native API inventory
• Current constant target: all 462 public JME_* constants from the native headers
• Native runtimes bundled in the wheel: jme plus calceph
• No CPython extension module; pure Python loader plus bundled native libraries
• Argument order, pointer ownership, output buffers, and return values are kept as-is from the native C API

Installation

pip install jmeph-ffi

End users do not need to download native binaries manually. The package ships its bundled jme and calceph runtimes inbuilt inside the wheel.

Native Libraries

The package bundles the same prebuilt runtimes as the PHP wrapper:

• linux-x64/libjme.so
• linux-x64/libcalceph.so
• linux-arm64/libjme.so
• linux-arm64/libcalceph.so
• macos-x64/libjme.dylib
• macos-x64/libcalceph.dylib
• macos-arm64/libjme.dylib
• macos-arm64/libcalceph.dylib
• windows-x64/jme.dll
• windows-x64/calceph.dll

The local/PHP release source below is for maintainers and package build refresh only, not for normal users.

Local source for those prebuilt runtimes during development:

Copy from a local checkout of jpl-moshier-ephemeris-php/libs

Published runtime source:

https://github.com/jayeshmepani/jpl-moshier-ephemeris-php/releases/tag/prebuilt-libs

You can override discovery with:

• JME_LIBRARY_PATH
• JME_CALCEPH_LIBRARY_PATH

Search order:

1. explicit environment override
2. bundled src/jpl_moshier_ephemeris/libs/<platform>/
3. common system library paths

Quick Start

from jpl_moshier_ephemeris import (
    JME_BODY_SUN,
    JME_CALC_SPEED,
    JME_CALENDAR_GREGORIAN,
    JmeEph,
    c_double,
    create_string_buffer,
)

jme = JmeEph()

jd = jme.jme_julian_day(2000, 1, 1, 12.0, JME_CALENDAR_GREGORIAN)
xx = (c_double * 6)()
err = create_string_buffer(256)

rc = jme.jme_calc_ut(jd, JME_BODY_SUN, JME_CALC_SPEED, xx, err)
print(rc, list(xx), err.value.decode())

Development

python -m pip install -e ".[dev]"
python scripts/fetch_prebuilt.py
python -m ruff check .
python -m ruff format . --check
python -m pyright
python -m pytest
python -m build
python -m twine check dist/*

The test suite verifies:

• 204/204 configured ctypes function signatures
• 462/462 generated JME_* constants
• import and runtime loading
• basic native contract calls such as version, Julian day conversion, calculation, houses, ayanamsa, Delta-T, split-degree, body naming, and refraction
• optional source-surface audit against the local native jpl-ephemeris- tree

License

MIT. The Python package and the project-owned JME native library are intended to remain under MIT-compatible distribution.