Zīdsch-i Sultānī

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Latin translation of the Zīdsch-i Sultānī by Thomas Hyde

The Zīdsch-i Sultānī ( Persian زیجِ سلطانی, DMG Zīǧ-i Sulṭānī , also known as Zīdsch-i Ulugh Beg or Zīdsch-i Gūrgānī ), fully Zīdsch-i Jadīd-i Sultānī , is an astronomical treatise, the main part of which is an extensive catalog of stars and which is under the direction of the Muslim mathematician and astronomer Ulugh Beg was compiled in 1437. In fact, it was a joint product of a group of Islamic scientists based on surveys and observations carried out in Ulugh Beg's observatory in Samarkand from 1420 onwards. Participants included the Islamic astronomers al-Kashi and ʿAlāʾ ad-Dīn ʿAlī ibn Muhammad al-Qushdschī .

The Zīdsch is considered the most up to that time worked best and most extensive catalog of stars , which all previous works, such as the Almagest of Claudius Ptolemy , Abd ar-Rahman as-Sufi Book of Fixed Stars and the Maragha observatory compiled Zīdsch-i Ilchani surpassed. The mathematical and astronomical data written down in the Zīdsch-i-Sultani were only surpassed a few decades later in the 16th century by the work of Taqi al-Din and later by Tycho Brahe .

content

In the introduction, Ulugh Beg praised the collaboration with Mūsā Qāḍīzāda , al-Kashi and al-Qushdschī, who were undoubtedly largely responsible for the underlying observations and the preparation of the tables.

The foreword of the Zīdj consists of four sections. In addition to a chronology in which different systems of time calculation are described, a treatise on the practice of astronomy, especially on the implementation and applicability of an observation, a chapter with tabular information on the movement of the sun, moon and planets based on a geometric system of the universe and an insert on astrology. In addition, the work contains a number of mathematical principles (see Ulugbek Madrasa ), such as tables of trigonometric functions.

The core of Ulugh Begs Zīdsch, however, is the outstanding star catalog, in which the names and the ecliptic coordinates of a total of 1018 stars are listed. In addition, there is some information on the precession of the equinoxes , i.e. on the shifting of the times of the equinoxes .

Outstanding features

Many Islamic astronomers operating before Ulugh Beg had mostly adopted the information from Ptolemy in their star catalogs , adapting his position data by correcting them for the effect of precession , i.e. the gyration that describes the earth around its axis. In contrast, Ulugh Beg and his colleagues took the trouble to redefine the positions of a total of 992 fixed stars between 1420 and 1437 using larger and therefore more precise observation instruments. Some clear deviations from the values ​​handed down by Ptolemy were found and adjusted. In addition, the list includes the data of a further 26 stars, which were taken from the catalog Book of Fixed Stars by Abd ar-Rahman as-Sufi from the year 964. While the positions of the first 992 objects could be determined in our own observatory, the other stars were too far in the southern hemisphere to be over-served from Samarkand.

A particularly impressive part of this work is a sine table in which, on 18 pages, the sine values ​​in the range from 0 ° to 87 ° for every arc minute up to five sexagesimal places (corresponding to nine decimal places) and between 87 ° and 90 ° six sexagesimal places (11 decimal places) are recorded.

The outstanding achievement is the accuracy of the position and time information given in this work. In 1437, Ulugh Beg determined the length of the sidereal year to be 365.2570370… d = 365 d 6 h 10 m 8 s , with an accuracy of +58 s . For their measurements, which extended over many years, the group used a sextant with a radius of 40.212 m. This value was improved 88 years later in 1525 by Nicolaus Copernicus . Ulugh Beg also measured the earth's orbital inclination at 23 ° 30 'and 17 "and thus came within 32 s of the current value. This was the most accurate value up to this point in time, which could only be improved by Copernicus and Tycho Brahe , which in turn is still accepted today.

Importance and distribution

Due to the aforementioned achievements, Ulugh Begs Zīdsch is, at least in the Islamic world, one of the most important of the Middle Ages. It was extremely influential throughout the Orient and was used as a standard work until the 19th century. Shortly after its publication, Yahya al-Mutali translated it into Arabic and Ibn as-Salah into Turkish. Editions in Persian and Hebrew were also produced in various regions.

In Europe, however, it did not become better known until the middle of the 17th century, almost five decades after the publication of Tycho Brahe, although copies of the Zīdsch existed in various libraries in Europe, such as Oxford and Paris, shortly after it was written . Crucial for the attention in Europe was the dissemination of a Latin translation of this work, which the British linguist Thomas Hyde published in Oxford in 1665 under the title Tabulae longitudinis et latitudinis stellarum fixarum ex observatione Ulugbeighi . In 1767 the contents of the Zīdsch were finally taken up by G. Sharpe. References to this can also be found in edition Vol. XIII. the Memoirs of the Royal Astronomical Society of Francis Baily from the year 1843rd

literature

  • ES Kennedy: A Survey of Islamic Astronomical Tables . In: Transactions of the American Philosophical Society , 46 (2), 1956, pp. 3-4, 44-5.
  • LPEA Sedillot (1808–1875): Tables astronomiques d'Oloug Beg, commentees et publiees avec le texte en regard . Tome I, 1 fascicule. Paris 1839. A relatively unknown work, but it is referenced in the Bibliographie generale de l'astronomie jusqu'en 1880 by J.
  • LPEA Sedillot (1808–1875): Prolegomenes des Tables astronomiques d'Oloug Beg, publiees avec Notes et Variantes, et precedes d'une Introduction . F. Didot, Paris 1847.
  • LPEA Sedillot (1808–1875): Prolegomenes des Tables astronomiques d'Oloug Beg, traduction et commentaire . Paris 1853.

Remarks

  1. ↑ Note: For Thompson, the fixed stars included in the catalog are given as 994 and those adopted by as-Sufi as 27. Many other sources give the values ​​992 and 26. For this article, the more conservative values ​​have been used.

Individual evidence

  1. ↑ a b c d e Benno van Dalen: Ulugh Beg: Muḥammad Ṭaraghāy ibn Shāhrukh ibn Tīmūr. Springer science + business media, accessed April 4, 2011 .
  2. ↑ a b Salah Zaimeche: The Scholars of Samarkand. FSTC limited, accessed October 18, 2019 .
  3. ↑ a b c Kevin Krisciunas: The Legacy of Ulugh Beg. Carrie books, accessed April 3, 2011 .
  4. ^ A b Gary D. Thompson: The Entry of Arabic Star Names into Europe. 2001, accessed April 3, 2011 .
  5. ↑ a b Ulugbek’s observatory. Advantour, accessed April 3, 2011 .
  6. ^ Hugh Thurston: Early Astronomy . Springer, New York 1994, ISBN 0-387-94107-X , pp. 194 (English).