Ulug Begs Observatory

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The ruins of the observatory, the round floor plan was reconstructed. The ivan in the center of the picture leads to the remains of the large sextant.
Underground parts of the sextant
Ulug Beg Monument not far from the observatory

The observatory of Ulug Beg ( Uzbek Улуғбек расадхонаси Ulug'bek rasadxonasi ) called Gurkani Zidsch (Gurkani Zij) or Zidsch-e Gurkani ( Zij-e Gurkānī, "Observatory Gurkāni "), located two kilometers from the center of the Uzbek city of Samarkand away . Today you can only find ruins of the observatory and a museum.

The observatory was built in 1424–1428 by the Timurid prince Ulug Beg for the observations of astronomers at the Ulugbek Madrasa . The observatory that Ilchan Hülegü had built for Nasir ad-Din at-Tusi in Maragha in the Persian province of Āzarbāydschān served as a model . It was a three-story round building 46 m in diameter and 30 m high. Since telescopes for precise observation were not yet known, he improved the accuracy of the observations by extending the Fakhri sextant to a radius of about 36 meters. There were also smaller instruments like an armillary sphere .

By observing the sun with the sextant for many years, Ulugh Beg and his astronomers al-Kaschi and Qadi Zada ​​determined the inclination of the ecliptic as 23 ° 30 'and 17 "(corresponds to the value at that time to a few degree seconds) and the sidereal year as 365 days 6 hours 10 minutes and 8 seconds (with a difference of 58 seconds compared to today's value). This accuracy is comparable to the determination of the tropical year as 365 days 5 hours 49 minutes and 20 seconds (deviation 35 seconds) by the Chinese astronomer Guo Shoujing with a 10 meter high gnomon at the Gaocheng Observatory near Dengfeng , which he used in 1278 to create the Shou Shi calendar performed. They also examined the precession of the equinoxes .

Ulug Beg's star tables

The mathematical and astronomical work was summarized in the Zij-i-Sultani . It contains the mathematical basics (such as tables of trigonometric functions), the observation methods, tables of planetary movements, astrological chapters and a new star catalog . Based on al-Kaschi's star catalog Chagani Zidsch , the astronomers compiled a star catalog with 1018 stars with position information between 1420 and 1437. 992 stars were measured in Samarkand itself; the catalog was supplemented by 26 stars from Al-Sufi's catalog of 964 , which cannot be observed from Samarkand. This is the first catalog since Ptolemy to be based on new measurements. Before that, the Muslim astronomers had essentially taken the star tables from the Almagest and corrected them for precession . With an average deviation of 11 arc seconds for longitudes and 8 for latitudes, the accuracy clearly exceeded the Almagest (58 and 37 seconds, respectively) and was only exceeded by Tycho Brahe more than a hundred years later .

After Ulug Beg's murder, the observatory was destroyed, but the astronomer Ali al-Qushji (d. 1474) was able to escape to Tabriz with a copy of the star tables . He later taught at the madrasah at Hagia Sophia in Istanbul . From there the tablets came to Western Europe. In Istanbul, around 1575 , Taqi ad-Din took Ulug Beg's observatory as a model for the observatory of the Ottoman Sultan Murad III. The Gurchani Zij was also the model for the five observatories, Jantar Mantars , which Maharaja Jai Singh II (1688–1743) built in Delhi , Ujjain , Mathura , Varanasi and Jaipur . His largest instrument reached a height of 27 m.

Only the underground part of the sextant was preserved and was discovered and excavated in 1908 by Vassily Lavrentyevich Vyatkin. The Russian astronomer Shcheglow examined the continental drift by comparing the historical meridian alignment of the sextant with the current position of the meridian.

The Ulugh Bek Astronomical Institute of the Uzbek Academy of Sciences and the Samarkand State University have maintained a teaching observatory in Samarkand since 2006.

literature

  • VP Shcheglov: Astronomical azimuths of terrestrial objects as indicators of the rotational motions of the continental blocks. Soviet Astronomy 21, No. 4, July-August 1977, pp. 499-502 ( translation by Edward U. Oldham )

Web links

Commons : Ulug Begs Observatory  - collection of images, videos and audio files

Individual evidence

  1. ↑ Thomas Hyde (1636-1703). Tabulae long. ac lat.stellarum fixarum, ex observatione Ulugh Beighi, Tamerlanis Magni nepotis, regionum ultra citraque Gjihun (i. Oxum) principis potentissimi. Ex tribus invicem collatis MSS Persicis jam primum luce ac latio donavit, et commentariis illustravit Thomas Hyde. In calce libri accesserunt Mohammedis Tizini tabulae declinationum et rectarium ascensionum. Additur demum elenchus nominum stellarum. Oxonii: Typis Henrici Hall, sumptibus authoris; 1665

Coordinates: 39 ° 40 ′ 29.1 ″  N , 67 ° 0 ′ 20.4 ″  E