About azmth
azmth is a free, real-time satellite tracker. It shows more than 15,400 active satellites orbiting Earth on an interactive 3D globe, predicts when any of them will pass over your location, detects freshly launched Starlink trains, and explains the orbital mechanics behind all of it in plain language. There is no signup and no advertising; the project is built by one developer and supported by donations. It has been featured in the Morning Brew newsletter.
The name comes from azimuth: the compass direction you look toward to find a satellite crossing your sky.
Data sources
- CelesTrakgeneral perturbations (GP) orbital data, maintained by Dr. T.S. Kelso. azmth refreshes its catalog every 2 hours, matching CelesTrak's update cadence.
- CelesTrak SATCAT for operator and country attribution.
- NASA Visible Earth for the Blue Marble Earth textures (public domain).
- NASA 3D Resources for the ISS and Hubble 3D models shown in the True Scale view (public domain).
- GeoNames for the city database used in manual location entry.
Methodology
Satellite positions are computed in your browser using the SGP4/SDP4 orbital propagation models via the satellite.js library, from each object's latest general perturbations elements. The catalog is baked into the site and refreshed every 2 hours by an automated pipeline, so the app makes no live calls to CelesTrak when you use it. Orbit classification (LEO, MEO, GEO, HEO) uses standard altitude bands derived from each satellite's elements; characteristics like sun-synchronous or Molniya orbits are derived from inclination, period, and eccentricity.
Accuracy
Pass predictions are typically accurate to within about 30 seconds for satellites with fresh orbital elements. Accuracy degrades for objects with stale elements or rapidly decaying orbits. Visibility labels (visible, daytime, in shadow) are geometric estimates and do not yet model per-satellite brightness. Satellite dimensions shown in the True Scale view are documented values for well-known satellites and clearly labelled class-level estimates for the rest.
Contact
Feedback and corrections: hello@azmth.space. If azmth is useful to you, you can support it at buymeacoffee.com/langguesser.