From orbital elements to your sky

CelesTrak publishes general perturbation orbital elements. SGP4 predicts a satellite position at the selected time. The browser converts that position into Earth-fixed coordinates for the globe and computes your azimuth, elevation and range.

Time, height and uncertainty

The globe, Sun and satellite details share one clock. Height is above the WGS84 ellipsoid. City observers currently use an explicitly approximate zero-metre ellipsoid height; you can supply a manual height. Orbital speed is not ground speed. Elements can become inaccurate after maneuvers. Retrieval older than six hours triggers a warning; optical recommendations are suppressed beyond 72 hours from the element epoch. The solar model is approximate and partial eclipses are excluded.