Observatory of Ulugbek
The biggest astronomical observatory of the time was built in Samarkand under Mirzo Ulugbek in the 1420 s. Here, the great astronomers Qazi-Zade Rumi, Djemshid Giyas al-Din Kashi and Ali Kushchi studied the skies. For three decades high-precision measurements of the motion of celestial bodies were conducted. Samarkand observatory became famous owing to the book “Zidj of Ulugbek”. This work contains a theoretical introduction and a catalog of 1018 stars. European scientists knew about the observatory in 1648 after the publication of “Zidj” at Oxford. In the late Middle Ages, the observatory was destroyed and deserted. The observatory was discovered by archaeologist V. Vyatkin at the beginning of 20th century. The structure had the form of a cylinder with a diameter of about 46 m. and was 30 m. high. Under the ground they excavated the remains of the basic instrument of the observatory – a giant (40 m. radius and 63 m. long) quadrant arc. It was used for measuring the movement of the Sun, Moon and other bodies.