#true north

• Agonic line — An imaginary line on the Earth's surface (an isogonic line of zero value) connecting points where the magnetic declination is zero; along this line, a compass needle points exactly to true geographic north.
• Astrocompass — The modern synonymous variant of the term astrocompass; a mechanical, optical, or electronic instrument used to determine true north, a vehicle's heading, and azimuth by directly sighting and tracking celestial bodies. This device plays a crucial role in high-altitude, high-precision aerial or maritime navigation, functioning as an independent redundant system in the event of magnetic or electronic GPS equipment failure.