What was the name of the official who observed the celestial phenomena and calculated the time in ancient times?

Astronomers were officials who observed astronomical phenomena and calculated time in ancient times. There were sixty astronomy students on the fourth terrace in the Tang Dynasty. Ming and Qing Dynasties belonged to Qin Tianjian. In the Qing Dynasty, there were astronomical eaters, including Manchu 16 people, 8 Han troops and 24 Han people. Astronomy students, Han 56. 2. The past refers to people who divine good or bad luck, choose days and measure geomantic omen.