No. Everything is computed entirely within your browser on your own device. Nothing is transmitted to any server, stored externally, or tracked in any way. This application is fully offline-capable and leaves no trace.

The compass requires a magnetometer. The tilt meter requires an accelerometer. GPS requires the Geolocation API. These are standard on smartphones. Desktop browsers lack orientation sensors — the compass then shows a fixed north-up display. All features degrade gracefully.

Accuracy depends on your device hardware. Phone magnetometers typically achieve ±2–5° when calibrated. GPS varies from ±3 m (open sky) to ±50 m (urban). Sun and moon positions are computed with sub-arcminute precision using SunCalc — far beyond practical observation needs.

Yes. Once loaded, the page has no network dependency. All calculations run locally. The only external request is for Google Fonts, and if that fails, the page falls back to system fonts automatically.

If the heading seems inaccurate, move your device in a figure-8 motion several times to recalibrate the magnetometer — this is a hardware-level calibration handled by your OS. Avoid nearby metal objects and magnetic cases. You can also tap the Calibrate button to reset the offset.