Ebu'l Kasım Amâcur Et- Türkî

Scholar of mathematics and astronomy (B. ?  – D. 944). His full name is Ebu’l Kasım Abdullah bin Amâcur et Türkî el-Herevî. He belongs to Amâcur Oğulları family which lived in 9^th and 10^th centuries and raised other scholars of mathematics and astronomy. Ebu’l-Kasım Abdullah b. Amâcur el-Turkî, his son Ebu’l-Hasan Ali and according to some sources his other son, or his brother Ali b. Amâcur and Ebu’l-Hasan’s servant Muflih b. Yunus belong to Amâcur family. They realized the longest observation researches in the history of Islamic astronomy and brought the results of these observations in various stars catalogues.

In classic and modern sources there is almost no information about the members of the family. There is some confusion between their names. His son Ebu’l-Hasan Ali is another scholar raised by his father and who is author of several books.

Amâcur family which attracted attention with their observation researches in the Islamic Civilization, realized observations for long years between 885 and 933. They recorded the results of these observations in numerous works. Amâcur family which existed in the same age with el-Battani who worked in Rakka realized a small part of their observations in Shiraz, a major part of it in Baghdad. According to Aydın Sayılı this family made between thirty and fifty observations of fixed stars, sun, moon and planets and they had an observatory as a family which realized the longest observations in the history of Islamic astronomy.

Ebu’l-Kâsım Amâcur et-Türkî was the first member of Amâcur family who became famous in the science of astronomy. He was educated in famous madrasahs of Baghdad, obtained a firm and fundamental Islamic education and became one of the most famous scholars of astronomy of his age by turning to positive sciences. One of the most notable services of Abdullah b. Amâcur et-Türkî to the science of astronomy is his review of the great astronomy scholar of Turkish origin el-Harezmî’s stars catalogue organized due to Sind-Hind method and production of a new catalogue accordingly. Renewing this work he authored a new map book of stars titled K. Ziycû’s Sind-Hind.

Amâcur et-Türkî wrote books titled "K. el-Fen”, "K.ez-Ziyc, el-Ma'ruf  bi'l-Hâlis”,  "K. Ziycü's-Sind Hint” and "K.ez-Ziyc el Ma'ruf  bi'l-Bedi” using the results he acquired observing stars. He did not remain contented with this and raised Ali and Ebu’l-Hasan of his sons in this field and come to a certain place in the science of astronomy. Thus an honorable family of science and culture passed to the history of Turkish astronomy and astrology known as “Amâcur Oğulları”. Ali b. Amâcur has a distinguished position in the science of astronomy. Primarily his deep interest, but also his family’s interest in astronomy resulted establishing an observatory in Baghdad spending great amounts of money. They observed in these private observatory stars, almost half a century, starting from the end of 880s. They produced catalogues of stars showing the results they obtained.

Ali b. Abdullah and his brother discovered important phases of lunar globe which were unknown until that date as a result of these observations, thus acquiring a very special knowledge. He presented with his serious researches that movements of the moon were dynamic and irregular and reaching a certain result was not possible. Thus he paved the way for the discovery of Ebû’1-Vefa Bozcanî, one of the great scholars of astronomy of Turkish origin at that time, about the variability of the moon’s third move. Sources state that he is the author of numerous books in this field and on these issues.

One has to add Müflih b. Yusuf to this Turkish family of astronomers. Müflih who was an intelligent servant of Amâcur family was deeply interested in the science of astronomy and being raised in the cultural environment of this Turkish family, he became a very valuable scholar of astronomy. He joined observations done by Amâcur brothers and became a great scholar in astronomy to be able to organize a catalogue of stars. According to Aydın Sayılı, the valuable scientist and historian of science, “Ahmed el-Fergâni, Amâcur Oğulları and Turkish scientists like them occupy an important and distinct place among the oldest astronomers of the Islamic World.”

Turkish scientists who drew attention in the field of astronomy with their long term observations are Ebu’l-Hasan Ali b. Amâcur et-Türkî and his son Ebu’l-Kasım Ali b. Amâcur et-Türkî. They worked with Ali İbn-i Abdullah İbn-i Amâcur of the same family in the same observatory. Amâcur family realized around fifty observations between the years 887 and 934. The famous astronomer İbn-i Yunus stated that their observations of moon were more accurate than the ones of Ptolemy and he benefited from these observations in his studies. Father-son Amâcurs who realized the first long-term observations in the Islamic World published many catalogues of stars. 

REFERENCE: Emir Ali / Ruh-u İslâm (Çev. Ömer Rıza Doğrul, 1341),  Zeki Velidi Togan / Umumi Türk Tarihine Giriş (s. 90, 1946), Aydın Sayılı / Türkler ve Bilimler (1976), Emel Esin / Türk Kültür Tarihinin İç Asya’daki Erken Safhaları (s.19, 1985), Şaban Döğen / İslam ve Astronomi (s. 132, 1996), Zekeriya Kitapçı / Türklerin Arap Dili ve Edebiyatına Hizmetleri: Hilafet Ülkeleri (2004, s. 103), İhsan Işık / Ünlü Bilim Adamları (Türkiye Ünlüleri Ansiklopedisi, C. 2, 2013) - Encyclopedia of Turkey’s Famous People (2013).