Died: Istanbul. Founder and the director of the Istanbul observatory and worked in the fields of mathematics, astronomy, optics, and mechanics. First astronomer to use an automatic, mechanical clock for his astronomical observations. He advanced the arithmetic of decimal fractions and used them in the calculation of astronomical tables. He taught for a short while at various madrasas in Damascus. Spent 20 years in Egypt where he held positions as a teacher and qāḍī. Encouraged to deal with mathematics and astronomy by a grandson of `Alī Qūshjī (who collected and gave Taqī al-Dīn some of his works), by Jamshīd al-Kāshī, and by Qāḍīzāde. Taqī al-Dīn returned to Istanbul in 1570 and was appointed head-astronomer (Müneccimbaşı) by Sultan Selīm II upon the death of Muṣṭafā b. `Alī al-Muwaqqit  in 1571. This led to an imperial edict by Sultan Murad III in early 1579 to build an observatory which was unfortunately demolished by the State on 22 January 1580.  Among Taqī al-Dīn’s 20 astronomical works: (1)"Sidrat muntahā al-afkār fī malakūt al-falak al-dawwār (= al-Zīj al-Shāhinshāhī)" which was prepared according to the results of the observations in Egypt and Istanbul in order to correct and complete Zīj-i Ulugh Beg; (2) a zīj entitled "Jarīdat al-durar wa kharīdat al-fikar" which uses decimal fractions in trigonometric functions.  [Fazlioglu]