Zij-i Ilkhani

Zij-i Ilkhani or Ilkhanic Tables (literal translation: "The Ilkhan Stars", after ilkhan Hulagu, who was the patron of the author at that time) is a book with astronomical tables of planetary movements by a Persian astronomer Nasir al-Din al-Tusi in collaboration with other astronomers at the Maragha observatory. It was written in Persian and later translated into Arabic.

The book contains tables for calculating the positions of the planets and the names of the stars. It included data derived from the observations of the stars and planets over 12 years in the Maragha observatory, completed in 1272. The planetary system of Tusi was the most advanced of his period and was used extensively until the development of the heliocentric model in the time of Copernicus.

The book also describes a method of interpolation between the observed positions, which in modern terms may be described as a second-order interpolation scheme.

History

Hulagu Khan believed that many his military successes were due to the advice of astronomers (who were also astrologers), especially of al-Tusi. Therefore when al-Tusi complained that his astromical tables were 250 years old, Hulagu gave permission to build a new observatory in a place of al-Tusi's choice (he chose Maragheh). A number of other prominent astronomers worked with al-Tusi there, such as Muhyi al-Din al-Maghribi, Mu'ayyid al-Din al-'Urdi, from Damascus, Qutb al-Din al-Shirazi, and Hulagu's Chinese astronomer Fao Munji whose Chinese astronomical experience brought improvements to Ptolemaic system used by al-Tusi - traces of the Chinese system may be seen in "Zij-i Ilkhani". The tables were published during the reign of Abaqa Khan, Hulagu's son, and named after the patron of the observatory. They were popular until the 15th century.

ee also

* Zij

References

*Nasir al-Din al-Tusi, "Zij-i Ilkhani", British Museum, MS Or.7464.
*J. A. Boyle, "The Longer Introduction to the "Zij-i Ilkhani" of Nasir ad-Din Tusi", Journal of Semitic Studies (1963) 8(2), pp.244-254
*E. S. Kennedy, "A Survey of Islamic Astronomical Tables", Transactions of the American Philosophical Society, (1956) 46(2), pp. 3, 39-40.
*Javad H. Zadeh,"A Second Order Interpolation Scheme Described in the "Zij-i Ilkhani" ", Historia Mathematica (1985) vol. 12, pp. 56-59.