Angelus

Angelus is an Elixir library that returns one geocentric tropical ephemeris for a supplied instant. Its only public API is Angelus.get_ephemeride/1.

Supported Bodies

Angelus 1.0.0 returns these body atoms in a fixed order:

[
  :sun,
  :moon,
  :mercury,
  :venus,
  :mars,
  :jupiter,
  :saturn,
  :uranus,
  :neptune,
  :pluto,
  :north_node,
  :south_node,
  :lilith,
  :chiron
]

The public datetime range is 1900-01-01 through 2100-01-24, inclusive.

Installation

Angelus is not yet published to Hex. Add it from Git:

def deps do
  [
    {:angelus, github: "MonsignorEduardo/angelus", branch: "master"}
  ]
end

Requirements

• Elixir ~> 1.20.2 on Erlang/OTP 29.0.3.
• For supported platforms, no local C compiler or CSPICE installation is required when installing from Hex.
• Local source builds require a C compiler available as cc, plus Meson, Ninja, and the native dependencies used by the Meson subprojects.

Precompiled CSPICE-enabled native workers are provided for macOS Apple Silicon (aarch64-apple-darwin), Linux glibc x86_64 (x86_64-linux-gnu), and Linux glibc arm64 (aarch64-linux-gnu).

Quick Start

Fetch dependencies and compile the native worker:

mix deps.get
mix compile

When installed from Hex on one of those supported platforms, compilation downloads the matching precompiled angelus_worker. Local development in this repository can force a source build with ANGELUS_FORCE_BUILD=1 or just build.

Install the complete Angelus runtime data:

mix angelus.prepare

This downloads the JPL/NAIF kernels and the pinned Quirón SPK into priv/kernels/. The pinned SPK is verified against its catalogued SHA-256 checksum.

Calculate an ephemeris. Kernels load automatically on the first call:

{:ok, ephemeride} = Angelus.get_ephemeride(~U[1990-05-24 06:30:00Z])

ephemeride.sidereal_time
ephemeride.positions

Each result includes the UTC instant, weekday, Greenwich sidereal time, and the positions in this fixed order. Every position contains ecliptic latitude (lat), true-equatorial declination (decl), and direct/retrograde/stationary motion. All angular values are expressed in degrees; Angelus does not expose zodiac signs or formatted ecliptic longitudes. ephemeride.reference identifies Earth as the geocentric observer and supplies the PCK ellipsoid radii in km, flattening, coordinate frame, and aberration correction used by the calculation.

Print the same result in a terminal with an ISO 8601 instant:

mix angelus.ephemeride 2000-01-01T07:00:00-05:00

Development

Common commands:

mix setup
mix compile
mix test test/unit
mix consistency

By default, mix compile may use a published precompiled worker. To force a local source build while working on this repository:

ANGELUS_FORCE_BUILD=1 mix compile

If you have just installed, the repository also provides:

just build             # compile with CSPICE support
just build-stub        # compile stub worker only, no CSPICE download
just test              # run test/unit only
just test-integration  # build with CSPICE and run e2e tests
just test-e2e          # alias for test-integration
just clean             # remove local build outputs and downloaded native libraries

Unit tests live under test/unit. Integration tests require the real CSPICE worker and downloaded kernels.

Kernel and Data Licensing

Angelus does not include third-party ephemeris data. JPL/NAIF kernels and the Quirón SPK are downloaded separately and remain subject to their respective terms.

The source code in this repository is MIT licensed. Native artefacts include components from NAIF CSPICE, distributed under NAIF's respective terms.

Angelus is not affiliated with or endorsed by NASA, JPL, NAIF, IAU, or SOFA.