Orbital catalog · SGP4/SDP4 propagation · observer geometry
Orbital Commons presents the active satellite population as an interactive Earth-orbit field. CelesTrak mean elements, UTC propagation time, orbital regime, and ground-based observation geometry meet in a single workspace.
- Orbital population: navigate active catalog objects in a three-dimensional Earth-orbit view.
- Regime filters: examine LEO, MEO, GEO, and higher-altitude populations.
- UTC propagation: adjust the epoch and propagation speed using SGP4/SDP4.
- Spacecraft inspection: read catalog ID, element epoch, propagated position, velocity, altitude, inclination, period, and eccentricity.
- Orbit and ground traces: connect the selected spacecraft to its trajectory and Earth footprint.
- Observer geometry: place a terrestrial observer and inspect azimuth, elevation, range, and pass geometry.
- Display controls: compare physical and compressed radial scales, switch viewing direction, and manage graticules and orbit shells.
- Catalog search: locate spacecraft by name or NORAD identifier.
| Component | Specification |
|---|---|
| Catalog | CelesTrak active GP data |
| Exchange format | CCSDS OMM in JSON |
| Elements | Mean motion, inclination, eccentricity, right ascension of ascending node, argument of pericenter, mean anomaly, epoch, and perturbation terms |
| Propagation | satellite.js · SGP4/SDP4 · Web Worker |
| Time | UTC propagation epoch |
| Position | Geocentric propagated state and observer-relative geometry |
| Rendering | Three.js · instanced 3D orbital field |
The instrument uses a CelesTrak OMM catalog distributed through GeoGeek's orbit-active data snapshot. The propagated state depends on the selected UTC epoch and each object's element epoch.
The GeoGeek Observatory source contains the orbital engine, propagation worker, and orbital controls.
Instrument: https://geogeeklab.github.io/orbital-commons/
Lab: https://geogeeklab.github.io/lab.html
Instrument record: https://geogeeklab.github.io/records/lab-l04.html
GeoGeek note — an orbit is a relation among state, epoch, reference frame, and observer.
“星汉灿烂，若出其里” -- 曹操《观沧海》