Another Maraga instrument, to measure altitude and azimuth of astral bodies by two observers.

The Wikipedia gives, spelling the name differently: Maragheh observatory (Persian: رصدخانهٔ مراغه‎), was an institutionalized astronomical observatory which was established in 1259 CE under the patronage of the Ilkhanid Hulagu and the directorship of Nasir al-Din al-Tusi, an Iranian scientist and astronomer. Located in the heights west of Maragheh, East Azerbaijan Province, Iran, it was once considered one of the most prestigious observatories in the world.