In the outskirts of Samarkand, on Kukhak hill, stands Ulugbek’s Observatory – a unique historical and architectural monument. Having inherited the power over Movarounnahr from Amir Temur, his grandson Mirzo Ulugbek successfully combined royal duties with scientific activities. He is known worldwide as the founder of the famous Samarkand astronomic school. His crowning achievement, which brought him international fame, was compilation of star catalogue “Ziji jadidi Gurgani”. For almost twenty years Ulugbek, his tutor Qadi-Zada al-Rumi and his disciples Ali Kushchi and Giayath-ad-Din Jamshid conducted observations with the help of a huge astronomic instrument arranged in the specially built observatory. The construction of the observatory started in 1424 and in 1429 it was already completed and fully equipped. After the tragic death of Ulugbek the building was almost totally destroyed. Ulugbek’s disciple Ali Kushchi left for Istanbul and managed to rescue the catalogue “Ziji jadidi Gurgani”. For a long time afterwards the astronomers of the East and West used this work of the Uzbek scientist and referred to it in their researches. Compilation of star catalogues requires very hard and meticulous work. Star catalogues are of great scientific value, for they do not only show the location of stars in different periods but also help much in research of heavenly bodies’ movement. This was noted in the work by famous French astronomer Pierre-Simon Laplace, who called Ulugbek “the great observer”. He also remarked that “in Samarkand, the capital of his Realm, Ulugbek had himself compiled a new catalogue of stars and astronomic tables that had turned out to be the best ever before Tycho Brahe”.
For many years nobody even recalled Ulugbek’s observatory; its exact whereabouts was forgotten. In 1908 Abu Sayid Mahzum, an expert in rare manuscripts, found a mention about the construction of this structure, and the archeologist L. Vyatkin determined the location of its ruins at the top of Kukhak hill. He excavated the lower brickwork of the foundations and the arc of the angle measuring instrument.
The building of observatory was circular in shape and had three levels. The main astronomic instrument was a colossal quadrant, bedded deep in a narrow meridionally stretching ground slit. This cylindrical building, decorated with tiles, amazed Ulugbek’s contemporaries by the originality of its architectural design, so different from the traditional structures of Oriental architecture. Those who happened to see the observatory wrote that the observatory was decorated with mosaic and glazed tiles; the wall paintings inside represented the vault of the heaven, stars at their right locations, as well as the orbits of the planets.
The main instrument – vertical quadrant with an aiming sight was supplemented with a horizontal graduated instrument - azimuth circle, installed on the top of the observatory. The calculations of scientists proved that the total height of the quadrant was 30 meters. The extant part of the arc of the gigantic quadrant fits a 10-metre-deep trench. The arc is made of two parallel marble-covered masonry bars placed 50 centimetres apart. It is graduated in degrees with the topmost point on the extant part of the quadrant indicating 57 degrees, and the bottommost point indicating 80 degrees. The marble plates have a groove for installing and moving astronomic instruments. On either side of the bars there are stone stairs, which the medieval scientists of the observatory could use while performing measurements. In 1915 a vaulted cover was built over the extant part of the quadrant. Though being represented by a rather small original fragment, today this instrument makes an unforgettable impression on its visitors.
Next to the quadrant is Ulugbek’s Museum. The interior of the museum is decorated with frescoes depicting episodes from the great scientist’s life. The frescoes are made by the famous Uzbek artist Chingiz Akhmarov. On display in the museum there are also ancient astronomic instruments similar to those of the 15th century, astronomic tables and other artifacts. Of great interest are marble fragments of the horizontal azimuth disk with polished surface and grooves, circles, letters and figures on them, as well as the glazed clay bowls that served as an artificial horizon when filled with liquid. Next to the museum stands a monument to Ulugbek by the famous Uzbek sculpture Mukhtar Musabaev.