On August 17, 1990 (June 27 of the Lunar calendar), the first astronomical ring was built in China.

On August 17, 1990, China, in cooperation with Danish astronomers, developed the effective caliber of the world's largest reflective fully automatic level ring, 240 mm, the Shaanxi Observatory of the Chinese Academy of Sciences was installed.

China has the first astronomical ring.

After the initial deployment, the observation of the Northern star and other distant stars at a distance of about 782 light-years from the Earth has shown good stability, good image quality, which marks the Chinese astronomy in this field to enter the world line, and after its official use, it can be observed 630 times higher than the extreme distance of the human eye, and more than 100,000 stars can be observed throughout the year, providing more than ten thousand precise positions.