Al Battani (ca. 850-923) was an arabastronomer (also spelled Al Batani, latinized Albategnius, Albategni, Albatenius; full name Abū ʿAbdullāh Muḥammad ibn Jābir ibn Sinān ar-Raqqī al-Ḥarrani aṣ-Ṣabiʾ al-Battānī), born in Harran near Urfa. His epithet as-Sabi suggests that among his ancestry were members of the Sabian sect who worshipped the stars, however, his full name affirms that he was Muslim.
Al Battani worked in Syria, at ar_Raqqah and at Damascus, where he died. He was able to correct some of Ptolemy's results and compiled new tables of the Sun and Moon, long accepted as authoritative, discovered the movement of the Sun's apogee, treats the division of the celestial sphere, and introduces, probably independently of the 5th centuryindian astronomer Aryabhatta, the use of sines in calculation, and partially that of tangents, forming the basis of modern trigonometry. He also calculated the values for the precession of the equinoxes (54.5" per year) and the inclination of Earth's axis (23° 35').
His most important work is the Kitāb az-Zīj ('the book of tables') with 57 chapters, which by way of latin translation as De Motu Stellarum by Plato Tiburensis in 1116 (printed 1537 by Melanchthon, annotated by Regiomontanus), had great influence on European astronomy. A reprint appeared at Bologna in 1645. Plato's original manuscript is preserved at the Vatican; and the Escorial Library possesses in manuscript a treatise by Al Battani on astronomical chronology.
External links
History of Mathematics (http://www_gap.dcs.st_and.ac.uk/~history/Mathematicians/Al_Battani.html)
In trigonometry, Albategnius introduced an important innovation--the use of the semi-chord of the double arc for the chords employed by Hipparchus and Ptolemy.
Of the other trigonometrical lines, the tangent appears to have been known to him, but not used; the cosine and secant were of later invention.
In astronomy, Albategnius, repeating with greater accuracy and better instruments the observations recorded by Ptolemy, determined the annual ammount of precession as 54", instead of 36"; a very much nearer approximation to the true amount.
Offset to the west of the crater mid-point is the central peak of Albategnius.
Albategnius is located to the south of the Hipparchus crater and to the east of Ptolemaeus and Alphonsus craters.
The Albategnius crater is believed to have been featured prominently in an early sketch drawing by Galileo in his book Sidereus Nuncius published in 1610, appearing along the lunar terminator.
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