Named on the occasion of the 600th anniversary of the birth of the Korean king Sejong (1397–1450), renowned for his many achievements in astronomy. He built the Royal Observatory of Choson in Seoul in 1437, equipping it with a whole series of astronomical instruments and installing an automatic striking clepsydra. He revised the Chinese calendar for Korean use and invented the rain gauge. He established the Hangul alphabet, which is still used throughout Korea. (M 30801) _ _.