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    Astrolabe

    Astrolabe

    An astrolabe is an ancient astronomical instrument used for solving problems related to time and the position of the stars. It was widely utilized in the Islamic world and medieval Europe for navigation, timekeeping, and surveying.

    World Magnetic Model

    World Magnetic Model

    The World Magnetic Model (WMM) is the standard geomagnetic reference used for navigation, attitude and heading systems worldwide. Produced jointly by NOAA NCEI and the British Geological Survey and sponsored by the U.S. NGA and the U.K. Defence Geographic Centre, the current version (WMM2025) was released on 17 December 2024 and is valid through 31 December 2029.