# shashwatak/satellite-js

Modular set of functions for SGP4 and SDP4 propagation of TLE and OMM.

Repository: https://github.com/shashwatak/satellite-js
Canonical: https://ross.abutalabs.com/products/satellite-js
Language: TypeScript
License: MIT
License Family: permissive
Last push: 2026-08-20T16:45:38+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 82, longevity 100
- inputs: {"age_days": 4861, "days_push": 13, "days_rel": 41, "gap_med": 76, "n_releases_24m": 6}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1082, forks 172 (observed 2026-08-28T04:03:30.911246+00:00)

## What it is
A TypeScript/JavaScript library implementing SGP4 and SDP4 orbital propagation from TLE and OMM data, usable in web and Node.js environments. It also provides coordinate transforms and utilities like doppler factor and shadow (eclipse) calculations.

## Use cases
- propagate satellite positions from TLE lines in javascript
- track ISS position in a web app
- compute look angles and geodetic position for ground stations
- convert OMM JSON orbit data to a satellite record
- calculate doppler shift for satellite pass predictions
- determine if a satellite is in Earth's shadow

## When to choose
- you need SGP4/SDP4 propagation in JavaScript or TypeScript
- you're building a satellite tracking or pass prediction web application
- you need coordinate transforms (ECI, geodetic) alongside propagation

## When to avoid
- you need high-precision ephemeris beyond SGP4/SDP4 accuracy
- you're working in Python or another non-JS language
- you need full mission-analysis astrodynamics suites

## Facets
- artifact type: library
- maturity: active
- function: simulation, math, sdk
- domain: simulation, astronomy, developer-tools
- platform: browser, cross-platform
- tags: sgp4, sdp4, tle, omm, satellite-propagation, orbital-mechanics, space, coordinate-transforms, doppler, nodejs, typescript

## Member repositories
- shashwatak/satellite-js (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:30.911246+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:51:17.866132+00:00, confidence not recorded.
  - readme: https://github.com/shashwatak/satellite-js (fetched 2026-08-28T04:03:30.911246+00:00, sha 558a4506b7fe)
- Data as of 2026-08-30T08:39:29.467469+00:00.