A panoramic view of historical Chinese astronomical instruments on the roof of the Beijing Ancient Observatory in Beijing, China, an astronomical observatory that dates from the 1400s. From left to right: equatorial armilla (1673) to measure true solar time and right ascension and declination of celestial objects; sextant (1673) to measure angular distance between any two stars less than 60 degrees apart, as well as angular diameters of the sun and moon; azimuth theodolite (1715) to determine azimuth and altitude (elevation angle); ecliptic armilla (1673) to measure ecliptic longitude difference and latitude; celestial globe (1673) to determine azimuth and altitude of objects, particularly at rising and setting times; new armilla (1744) with quadrant (1673) ??to measures altitudes or zenith distances - behind.