Compass Error Calculator Live

Compass Error Calculator is a marine navigation tool for determining gyro and magnetic compass error using astronomical observations. The app calculates the true bearing of the Sun, Moon, selected planets and navigational stars for a given UTC date, time and position. The calculated true bearing can be compared with an observed gyro or magnetic compass bearing to determine compass error. Features include: • True bearing calculation for the Sun, Moon, planets and navigational stars • Gyro compass error calculation • Magnetic compass deviation calculation • Course and bearing conversions • Calculation of GHA, SHA, declination, LHA and calculated altitude (Hc) • Amplitude calculation for observations near sunrise and sunset • Optional corrections for vessel speed, wind and current • Observation log stored locally on the device • Works offline – no internet connection is required for astronomical calculations Astronomical positions are calculated using the JPL DE440s SPICE ephemeris. The JPL DE440s SPICE kernel is distributed by NASA/JPL's Navigation and Ancillary Information Facility (NAIF). Compass Error Calculator is designed as a practical aid for mariners and for training and verification of traditional astronomical compass observations. The app does not collect or transmit personal data. Observation logs and settings remain locally on the user's device. Important: Compass Error Calculator is an aid to navigation. It does not replace approved navigational equipment, official nautical publications, or the navigator's responsibility for the safe navigation of the vessel.