Ulugh Beg Observatory, Samarkand

Timeline

1. c. 1420–1429Samarkand · SamarkandUlugh Beg built an observatory north of Samarkand, equipped with a giant mural quadrant (radius about forty meters) and observation chambers, gathering scholars such as Qazi-zadeh Rumi and continuing the observational tradition of the Maragha school.
2. 1431–1440Samarkand Observatory · SamarkandThe observatory entered its most productive phase; Ulugh Beg led his team in systematically determining the obliquity of the ecliptic and the precession of the equinoxes, and compiling a catalogue of stellar positions whose accuracy surpassed the earlier Ptolemaic tradition, laying the observational foundation for the Zij-i Sultani.
3. 1437–1449Samarkand · SamarkandThe Zij-i Sultani was completed and circulated, containing coordinates for about a thousand stars and calendrical computation tables; it became an important astronomical text for the Timurid Empire and the later Islamic world, with its influence extending into early modern Europe.