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(Arabic and Persian for astronomical tables, manuals), astronomical tables, which, as a rule, included star catalogs; they were compiled in many countries of the Orient during the Middle Ages. Dozens of zij by different authors are known. The most complete are the Zij Il-Khani and the Zij Ulug Beg. The Zij Il-Khani is one of the principal works of the 13th-century Maragha Observatory. It was compiled under the direction and with the direct participation of the Azerbaijani astronomer Nasir al-Din al-Tusi (Nasireddin Tusi). It contains a catalog of the bright stars and an extensive preface, which includes geographic tables and tables of sines and tangents, generally accurate to the fifth decimal point.
The Zij Ulug Beg, one of the most complete and detailed zij, was compiled in Ulug Beg’s observatory in Samarkand. It contains a catalog of the positions of 1,018 stars in the ecliptic coordinate system, most of which were obtained from observations in Samarkand. The introduction contains a compendium of astronomical knowledge in the Orient in the 15th century and includes numerous tables for astronomical calculations. Among these, the tables of sines and tangents are accurate, as a rule, to the ninth decimal point. The Zij Ulug Beg represents the highest stage achieved by Oriental astronomy before the beginning of optical observations.
REFERENCESMamedbeili, G. D. Osnovatel’ Maraginskoi observatorii Mukhammed Nasireddin Tusi. Baku, 1961.
Kary Niiazov, T. N. “Astronomicheskaia shkola Ulugbeka.” Izbr. trudy, vol. 6. Tashkent, 1967.
Hevelius, J. Atlas zvezdnogo neba. Introduction by V. P. Shcheglov. Tashkent, 1968.
V. P. SHCHEGLOV