On the Solar Model and the Precession of the Equinoxes in the Alphonsine Zīj and its Arabic Sources (original) (raw)

E. S. Kennedy : Survey of Islamic Astronomical Tables 1956

This groundbreaking study from 1956 identified some 125 Islamic astronomical handbooks with tables and explanatory text prepared in Muslim lands between 750 and 1900. Before this publication two such works, called zij, zijes, (زيج ، ازياج , zîj, azyâj) in Arabic, were known, namely those of al-Khwarizmi (Indian tradition) & al-Battani (Greek tradition). Both of these, by historical accident, were known in al-Andalus and were the only zîjes to become known in medieval Europe . The number of zîjes now known is closer to 225 and these, together with countless other tables not contained in zîjes have confirmed Kennedy's impression that one of the most impressive achievements of the Muslim astronomers was the compilation of tables for all sorts of purposes. An interim report on all of these tables was published in 2001 in D. A. King & J. Samsó & B. R. Goldstein, ”Astronomical tables and handbooks from the Islamic world (750-1900)” in the journal Suhayl (www.academia.edu/34693241/). A new survey of all zîjes by Dr. Benno van Dalen of the Bavarian Academy of Sciences is nearing completion: see www.badw.academia.edu/BennovanDalen and www.bennovandalen.de/Research/research.html.

The rising and setting of the stars in the astronomical tables of Ibn Al-Raqqam Al-Andalusi

Archives Internationales d'Histoire des Sciences, 2012

Among the astronomical information about 58 stars given in the star table of Ibn al-Raqq×m al-Andalus÷ (d 1315), there are two particular columns with the longitudes of the ecliptic points that cross the eastern and western horizons of Tunis at the same time as these stars. Unlike other items of the same table, most of the manuscript values preserved in these two columns do not match an easy reconstruction using Ibn al-Raqq×m's purported parameters for the geographical latitude of Tunis and the obliquity of the ecliptic. In this paper, I show how, despite what it seems at a first sight, these columns could have been also computed according with the same parameter values underlying the remaining of the table.

An analysis of medieval solar theories

Archive for History of Exact Sciences, 2018

From Antiquity through the early modern period, the apparent motion of the Sun in longitude was simulated by the eccentric model set forth in Ptolemy's Almagest III, with the fundamental parameters including the two orbital elements, the eccentricity e and the longitude of the apogee λ A , the mean motion ω, and the radix of the mean longitudeλ 0. In this article we investigate the accuracy of 11 solar theories established across the Middle East from 800 to 1600 as well as Ptolemy's and Tycho Brahe's, with respect to the precision of the parameter values and of the solar longitudes λ that they produce. The theoretical deviation due to the mismatch between the eccentric model with uniform motion and the elliptical model with Keplerian motion is taken into account in order to determine the precision of e and λ A in the theories whose observational basis is available. The smallest errors in the eccentricity are found in these theories: the Mumtah. an (830):