In 1428 Ulugh Beg began to build his observatory three kilometres outside Samarkand. Its remnants were discovered under a shallow hill in 1908 by the Russian archeologist Viatkin. Only the underground section of the giant marble sextant seen on the left remains. Because relescope were not available at the time, Ulugh Beg achieved high accuracy through building his instruments at very large scale.
Photo: © ArchNet Digital Library, reproduced by permission.
Today's entrance to the underground remains of the observatory.
Photo: © Sigismund von Dobschütz; GNU Free Documentation license (Wikipedia)
Portrait of Ulugh Beg and the remains of the sextant of his observatory
Illustration: Turkish postage stamp issued 1983; public domain
Ulugh Beg's star catalogue in Latin translation. It was the most important star catalog of the era, recording the positions of 1000 stars. Unlike later star catalogs, all observations to create this catalog were made by the naked eye.
Illustration: Dudley Observatory, New York; public domain (US government)