Purple Mountain Observatory, also known as Zijinshan Astronomical Observatory, is a dual-use astronomical observatory operated by the Chinese Academy of Sciences, located at Purple Mountain east of Nanjing. The observatory conducts both open science, such as calculating the official Chinese calendar, and classified space domain awareness activities for the PLA Aerospace Force. The observatory's long-range precision mechanical tracking radars used for space surveillance are managed by PLAASF Base 26 as the Space Target and Debris Observation and Research Center.
The Purple Mountain Observatory was established in 1934 funded by the Nationalist Government of the Republic of China and administered by Academia Sinica. The longtime director of the observatory from 1950 to 1984 was Chinese astronomer Zhang Yuzhe. By the late 1980s, increasing light pollution in Nanjing meant Purple Mountain was no longer viable as a working observatory. It has since shifted its focus to public education, with much of the actual scientific work being carried out in its five branch observatories located at Qinghai (in Delingha), Ganyu, Xuyi, Honghe (in Jiamusi), and Qingdao.
The Minor Planet Center credits the observatory with the discovery of 149 minor planets between 1955 and 1983, while the observatory's PMO NEO Survey Program is credited with more than 600 discoveries between 2006 and 2013.
The observatory discovered the periodic comets 60P/Tsuchinshan and 62P/Tsuchinshan, as well as the non-periodic (Tsuchinshan), also known as Comet 1977 X, , and C/2023 A3 (Tsuchinshan-ATLAS). They are named after the postal romanization of the name (WadeâÂÂGiles: Tzu-chin-shan; pinyin: ZÃÂjënshÃÂn). Many asteroids were also discovered, including the Trojan asteroids 2223 Sarpedon, 2260 Neoptolemus, 2363 Cebriones, 2456 Palamedes, and the eponymous 3494 Purple Mountain.
The Chinese Near-Earth Object Survey (CNEOS), based at the Xuyi Station in Xuyi, Jiangsu, started observations in 2006. It uses a 1:04=1:20=1:80 m Schmidt telescope equipped with a 4K ÃÂ 4K CCD detector with the drift-scanning function. As of August 2012, the program has observed 149,971 asteroids, found 1,279 new provisional designation asteroids, and cataloged 251 numbered asteroids including five Jupiter trojans, two Hildian, and one Phocaea asteroid. The program has also observed the position of 824 near-Earth objects (NEOs) and discovered four new ones: the Apollo asteroid , and the three Amor asteroid , , and .
A total of 149 minor planets were discovered by the Purple Mountain Observatory between 1955 and 1983.
Several hundred minor planets were discovered by the observatory's PMO NEO Survey Program from 2006 to 2013.