sidereon 0.9.0

Python bindings for the Sidereon GNSS positioning engine (SP3 loading and SPP/RTK/PPP solves)

sidereon

GNSS and astrodynamics for Python: propagate satellites, predict passes, solve precise positions (SPP / RTK / PPP), and convert between coordinate frames and time scales — checked against the references the field trusts (Vallado, Skyfield, IGS, IERS).

Under the hood it's a Rust engine compiled into the wheel, so it's fast and the only runtime dependency is numpy. You just pip install sidereon.

Install

pip install sidereon

import sidereon
print(sidereon.__version__)

Quickstart: when does the ISS fly over you?

No data files, no setup — give it a two-line element set and a ground station, and ask when the satellite is above the horizon.

import sidereon
from datetime import datetime, timedelta, timezone

# Real orbital elements (grab fresh ones from CelesTrak any time).
iss = sidereon.Tle(
    "1 25544U 98067A   26178.50947090  .00006280  00000+0  12016-3 0  9996",
    "2 25544  51.6322 248.9966 0004278 238.4942 121.5629 15.49454046573359",
)

# A ground station: latitude, longitude in degrees (altitude in metres, optional).
berkeley = sidereon.GroundStation(37.87, -122.27)

# Every pass above 10° over the next 24 hours.
now = datetime.now(timezone.utc)
us = lambda t: int(t.timestamp() * 1_000_000)  # epochs are UTC unix microseconds
passes = iss.find_passes(
    berkeley, us(now), us(now + timedelta(days=1)), elevation_mask_deg=10.0
)

for p in passes:
    rise = datetime.fromtimestamp(p.aos_unix_us / 1e6, timezone.utc)
    print(f"{rise:%H:%M} UTC · {p.duration_s / 60:4.1f} min · peak {p.max_elevation_deg:2.0f}°")

Tle also gives you propagate() (TEME state arcs as numpy arrays) and look_angles() (azimuth/elevation/range over a time grid). Everything that takes time takes UTC unix microseconds and returns numpy arrays.

Precise positioning

The positioning engine is the other half of the library: feed it pseudoranges and a precise-ephemeris product and it returns a least-squares fix.

import sidereon

sp3 = sidereon.load_sp3(open("igs_product.sp3", "rb").read())

config = sidereon.SppConfig(
    observations=[
        sidereon.SppObservation("G01", 21_000_123.4),  # PRN, pseudorange (m)
        sidereon.SppObservation("G08", 22_517_889.1),
        # ...more satellites
    ],
    t_rx_j2000_s=...,          # receiver time
    t_rx_second_of_day_s=...,
    day_of_year=...,
    initial_guess=[0.0, 0.0, 0.0, 0.0],
    corrections=sidereon.SppCorrections(ionosphere=True, troposphere=True),
    with_geodetic=True,
)

fix = sidereon.solve_spp(sp3, config)
print(fix.position)   # numpy [x, y, z] ECEF metres
print(fix.geodetic)   # (lat_rad, lon_rad, height_m)
print(fix.used_sats)  # satellites that contributed

solve_rtk_float, solve_rtk_fixed, solve_ppp_float, and solve_ppp_fixed follow the same shape — typed config in, a result object with numpy positions, scalar attributes, and enum statuses out. Need the products? sidereon.data fetches and caches SP3, RINEX, and IONEX from the public archives.

What's in the box

• Orbits — SGP4/TLE and OMM, numerical propagation, passes, look angles, visibility
• Frames & time — TEME ↔ GCRS ↔ ITRS, GMST/GAST, geodetic ↔ ECEF, UTC/TT/TDB/UT1
• Bodies — Sun/Moon positions, eclipse, plus JPL SPK (DAF/.bsp) kernels
• Positioning — SPP, RTK (float/fixed), PPP (float/fixed), DOP, velocity
• GNSS data — SP3, RINEX (obs/nav/clock), CRINEX, ANTEX, IONEX, broadcast ephemeris
• Space situational awareness — conjunction/TCA screening, collision probability, CDM, covariance
• RF — link budget (FSPL, EIRP, C/N0, antenna gain)

The binding adds no modeling of its own: every result is exactly what the engine computes, returned as numpy arrays, typed objects, and real Python exceptions (sidereon.SidereonError and friends). Full signatures live in the bundled type stubs (sidereon/__init__.pyi).

Other languages

sidereon is one validated engine with first-class interfaces in Rust, Python, C, Elixir, and WebAssembly — same numbers everywhere. See the live demo and docs at sidereon.dev.

How it's validated

The SGP4 propagator is a Rust port of David Vallado's reference implementation, bit-exact to it. Frames and time are checked against Skyfield and IERS; the positioning stack is checked against IGS products. The wheel links the Rust sidereon-core engine statically, so there's no separate native install.

Building from source (for contributors): pip install maturin, then maturin develop from the repo. Tests: pytest.