Gaocheng Astronomical Observatory

This site has a long tradition of astronomical observations, from the time of the Western Zhou up to the early Yuan dynasty.

The astronomer Yi Xing (683–727) of the Tang dynasty built 20 standardized gnomons spread out over China to measure the equation of time dependent on the geographical location.

Following a proposition of Liu Zhuo from 604 AD, 10 of these were aligned along the meridian 114° east of Greenwich from Central Asia down to Vietnam in order to determine the circumference of the Earth and deviations from a perfect sphere.

South of the observatory, in the temple dedicated to Zhou Gong can be found a Shigui chart made by Yi Xing.

[2] The great observatory was built in 1276 in the early Yuan dynasty on the order of Kublai Khan and was designed by astronomers Guo Shoujing (1231–c.1215) and Wang Xun (1235–1281) to observe the movement of the sun and the stars and to record time.