sgp4
The C++ SGP4 routine that, given an Earth satellite TLE, computes its position.
Decision gist · record as of 2026-08-14
Yes. SGP4 is actively maintained, has no runtime dependencies, compiles cleanly on most systems with a pure-Python fallback, carries an MIT license with no restrictions, and has no known vulnerabilities. Install it if you need to compute satellite positions from TLE or OMM data; it is the standard Python interface to the official SGP4 algorithm.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Installs cleanly with no runtime dependencies.
- Actively maintained with recent releases; the C++ implementation compiles on most systems, but the package gracefully falls back to a slower pure-Python version if compilation fails.
License · maintenance · safety
MIT (permissive) — MIT license permits free use, modification, and distribution with minimal restrictions, making it suitable for both open-source and commercial projects.
last release 2026-07-03 (42 days) · last repo commit 2026-07-12 · 468 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 1,039,036 downloads/mo, #4,457 on PyPI
Alternatives
Verify before relying
pip install sgp4
from sgp4.api import Satrec
s = '1 25544U 98067A 19343.69339541 .00001764 00000-0 38792-4 0 9991'
t = '2 25544 51.6439 211.2001 0007417 17.6667 85.6398 15.50103472202482'
satellite = Satrec.twoline2rv(s, t)
jd, fr = 2458826.5, 0.8625
e, r, v = satellite.sgp4(jd, fr)
print(r) # position in km
print(v) # velocity in km/s- Whether the C++ extension will compile successfully on your target platform (graceful fallback exists but is slower).
- Performance characteristics of the pure-Python fallback relative to C++ for batch computations.
What it is and what it does
SGP4 is a Python wrapper around the official C++ implementation of the Simplified General Perturbations (SGP4) and Simplified Deep Space Perturbations (SDP4) satellite propagation algorithms. It takes Two-Line Element (TLE) sets or OMM (Orbit Mean Elements Message) data—the standard formats for describing satellite orbits—and computes the satellite's position and velocity at any given time. The package automatically selects between SGP4 (for low Earth orbit, periods under 225 minutes) and SDP4 (for higher orbits) based on the orbital parameters.
The package includes a fast C++ implementation that compiles on most systems, but falls back to a slower pure-Python version if compilation fails, ensuring portability. Results are returned as raw x,y,z Cartesian coordinates in the True Equator Mean Equinox (TEME) reference frame—an Earth-centered inertial frame. The package does not perform coordinate transformations to other frames (J2000, ICRS, ECEF, WGS84) or compute latitude/longitude; those conversions are left to higher-level astronomy libraries like Skyfield, which builds on top of this one.
Use it for
- Track International Space Station or other known satellites by loading their TLE and computing positions at specific times.
- Build a satellite pass predictor that determines when a satellite will be visible from a ground location.
- Validate or debug TLE data by checking whether parsed orbital elements produce physically reasonable positions.
- Compute satellite positions for a large batch of times and satellites using the accelerated array routine.
- Integrate satellite propagation into a mission planning or conjunction assessment tool.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
SGP4 is actively maintained, has no runtime dependencies, compiles cleanly on most systems with a pure-Python fallback, carries an MIT license with no restrictions, and has no known vulnerabilities. Install it if you need to compute satellite positions from TLE or OMM data; it is the standard Python interface to the official SGP4 algorithm.
Install
sgp4 on PyPI
Before you install
Installs cleanly with no runtime dependencies. Actively maintained with recent releases; the C++ implementation compiles on most systems, but the package gracefully falls back to a slower pure-Python version if compilation fails.
License in practice
MIT license permits free use, modification, and distribution with minimal restrictions, making it suitable for both open-source and commercial projects.
Quickstart
pip install sgp4
from sgp4.api import Satrec
s = '1 25544U 98067A 19343.69339541 .00001764 00000-0 38792-4 0 9991'
t = '2 25544 51.6439 211.2001 0007417 17.6667 85.6398 15.50103472202482'
satellite = Satrec.twoline2rv(s, t)
jd, fr = 2458826.5, 0.8625
e, r, v = satellite.sgp4(jd, fr)
print(r) # position in km
print(v) # velocity in km/sVerify before relying
- Whether the C++ extension will compile successfully on your target platform (graceful fallback exists but is slower).
- Performance characteristics of the pure-Python fallback relative to C++ for batch computations.
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release !=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,!=3.5.*,!=3.6.*,!=3.7.*,!=3.8.*,!=3.9.*,>=2.7 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 42 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 1,039,036 / month, #4,457 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: Science/ResearchProgramming Language :: Python :: 2Programming Language :: Python :: 2.7Programming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Topic :: Scientific/Engineering :: Astronomy |
Evidence: sgp4-2.27-py3-none-any.whl
Tags
Let your AI agent find packages like this
Example. Real query, live index.
You found this page by searching. An agent finds it by wishing: SkillFed indexes 14,416 PyPI packages by what they can do, searchable in plain language.
wish › “satellite position propagation”
- sgp4Computes satellite positions in Earth orbit from TLE or OMM orbital…
- skyfieldSkyfield computes high-precision positions for planets and Earth…
- ephemPyEphem computes high-precision positions of planets, moons, stars,…
Give your agent the search over MCP, or paste the wish link into any chat.
More Astronomy packages
Albumentations applies image transformations to training data, supporting classification, segmentation, object detection, and pose estimation with a unified API for images, masks, bounding boxes, and keypoints.
Install it if you need a unified, production-grade augmentation API for computer vision tasks.
Converts dates between the Gregorian calendar and 15+ alternative calendar systems including Hebrew, Islamic, Julian, French Republican, Mayan, and others, plus calculates holidays across North American, Jewish, and other traditions.
Install only if you actually need multi-calendar support; the single pymeeus dependency is manageable.
Converts between Julian dates and Gregorian or Julian calendar dates, storing Julian dates as pairs of floating-point numbers for maximum precision.
However, be aware that it will not receive bug fixes or updates—verify that its behavior matches your requirements before committing to it in a production system.
PyERFA wraps the ERFA C library (Essential Routines for Fundamental Astronomy) as NumPy universal functions, exposing key astronomy algorithms for scalar or array inputs.
Install it if you need fundamental astronomy calculations or if another package depends on it.
PyMeeus implements astronomical algorithms from Jean Meeus's classical reference, providing Python classes for computing celestial positions, lunar phases, planetary phenomena, and time conversions with minimal dependencies.
However, verify Python version compatibility first and consider whether other libraries better suit production-grade use cases.
PyEphem computes high-precision positions of planets, moons, stars, comets, and asteroids in the sky for any observer location and date, using C-based numeric routines from the XEphem astronomy application.
See also pyorbital · skyfield · jplephem · pystac-ext-sat · astropy-iers-data · sxtwl · pygeodesy