Early Astronomy in the University of Michigan Collections

Work of the Observatory: Zīj of Ulugh Beg (d.1449)

15th century Samarqand

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)

Underground space in the Smarqand observatory
Interior of the underground sections of the giant sextant of the observatory built for Ulugh Beg at Samarqand. Photograph © Hatice Yazar, 1990. Source: MIT Libraries, Aga Khan Visual Archive via Archnet (CC BY-NC 4.0 license)

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

Select Bibliography

  • Isl. Ms. 763 online catalogue record (R Dougherty)
  • SPEC RARE QB 6 .U442 online catalogue record
  • “Rasdkhanah-i Ulugh Beg (Samarkand, Uzbekistan)” ARCHNET (available online)
  • Cavin, Jerry D. 2011. “Ulugh Beg.” In The Amateur Astronomer’s Guide to the Deep-Sky Catalogs, edited by Jerry D. Cavin. New York, NY: Springer New York: 51-54.
  • de Blois, François C., David A. King, and Julio Samsó. “Zīdj.” In Encyclopaedia of Islam, Second Edition, edited by Peri Bearman et al.
  • Kennedy, Edward S. 1956. “A Survey of Islamic Astronomical Tables.” In Transactions of the American Philosophical Society, new series 46 (2): 123-177 (available online)
  • Knobel, Edward Ball. 1917. Ulugh Beg’s Catalogue of Stars, rev. from all Persian Manuscripts Existing in Great Britain, with a Vocabulary of Persian and Arabic Words. Washington, DC: The Carnegie Institution of Washington (available online).
  • Krisciunas, Kevin. 1992. “The Legacy of Ulugh Beg.” In Central Asian Monuments, edited by Hasan B. Paksoy. Istanbul: ISIS Press: 95-103.
  • Manz, Beatrice F. “Ulugh Beg.” In Encyclopaedia of Islam, Second Edition, edited by Peri Bearman et al.
  • Saliba, George. 2004. “Reform of Ptolemaic Astronomy at the Court of Ulugh Beg.” In Studies in the History of the Exact Sciences in Honour of David Pingree, edited by Charles Burnett et al, Leiden: Brill: 810-824.
  • Verbunt, F. and R. H. van Gent. 2012. “The Star Catalogues of Ptolemaios and Ulugh Beg: Machine-readable Versions and Comparison with the modern Hipparcos Catalogue.” Astronomy & Astrophysics, 544: A31 (available online)

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