Early Astronomy in the University of Michigan Collections

Muḥammad Ṭaraghāy ibn Shāhrukh ibn Tīmūr, known as Ulugh Beg (d.1449), was governor of Transoxania and briefly Timurid sultan. He became famous for his patronage of mathematics and astronomy, establishing and supporting large madrasahs in Bukhara and Samarqand. He is perhaps most famous for the observatory established at Samarqand in 1420. He himself was knowledgeable and practiced in mathematics and astronomy, and gathered capable scholars who taught, designed instruments, and conducted the observational program culminating in an astronomical handbook (zīj) entitled the Zīj-i Sulṭānī or Zīj-i Gurkānī.

This manuscript (see the first two images) reproduces the tables provided in the astronomical handbook (zīj) compiled for Ulugh Beg (d.1449).

The tables featured here are part of the star catalogue, originally completed in early 841 H [1437 CE]. This star catalogue relied on the magnitudes of al-Ṣūfī (d.986) but was the first to provide updated positions based on new, independent measurements rather than simply adjusting for precession the coordinates provided by Ptolemy. The measurements were performed using the gigantic instruments of the observatory, including a colossal meridian arc (referred to as a suds or sextant but possibly greater in extent) running through the center of the building and mostly below ground. The enormous size allowed for remarkably accurate measurement, more accurate than those of Ptolemy. (cf. Verbunt and van Gent 2012)

In this manuscript, the original star positions of the Ulugh Beg catalogue have been adjusted for precession to the year 1120 H [1708/9 CE], perhaps by the copyist who prepared this manuscript for himself (cf. the opening of the star catalogue on p84 of the manuscript and the copyist’s statement at the conclusion of the star catalogue on p117)

Editions of the star catalogue prepared for Ulugh Beg (d.1449) were eventually produced in Europe, though not before the work of Tycho Brahe. This volume (see the last four images) contains Thomas Hyde’s edition and Latin translation of 1665. About 700 of the 1018 stars included were based entirely on Ulugh Beg and the remainder derived from Ptolemy in one or both coordinates.

While recognition of the contributions of the Samarqand observatory were delayed in Europe, the zīj and especially star catalogue of Ulugh Beg became the standard, in wide use throughout the Islamic world. It has since been widely acknowledged that as it flourished the observatory was conducting “the most advanced observations and analysis being done anywhere.” (Krisciunas 1992)

Observatory at Samarqand

Islamic Astronomy