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Mirza Muhammad Taraghay ibn Shahrukh ibn Timur
(22 March 1394, Sultaniyeh - 27 October 1449, Samarkand)

Astronomer, mathematician, geographer, historian

Mirza Ulugh Beg was born in 1394 in the city of Sultaniyeh (currently Iran) during his grandfather’s (Amir Temur’s) five-year campaign. His father was Amir Temur’s younger son Shohruh Mirza (1377-1447). The real name of Mirza Ulugh Beg named after Amir Temur’s father was Muhammad Taraghay. As a child he demonstrated a logical mind and sharp brain, for which his grandfather called him Ulugh Beg (Great Bey – translation from Turkic). It was under this name that he became known in history and fully justified the expectations of his grandfather.
Like most of the Timurids, he was brought up at the court of Amir Temur. His teachers were reknown scientists and writers of the time. It is not accidental that he became not only an outstanding scientist, but also a connoisseur of poetry like his brothers Ibrahim Sultan and Boysunkur Mirzo.

In 1405 Amir Temur died and following the failure of his grandson Khalil Sultan in 1409, the throne passed to Shahrukh. The same year, Ulugh Beg was declared governor of Transoxiana (part of Central Asia to the east of the Amudarya River) with the capital in Samarkand.

Shahrukh ruled from Herat and proved himself an outstanding statesman. In this complex political environment, he was not only capable of keeping together the empire created by Amir Temur for almost 40 years, but together with his son Ulugh Beg he secured peace and prosperity in the country.

Along with public affairs, Mirzo Ulugh Beg actively engaged in development of Transoxiana, built higher educational institutions (madrasahs) in Samarkand, Bukhara, Gijduvan and Karman. Keeping the tradition of his grandfather, he invited to Samarkand famous scientists, astronomers and mathematicians of the Islamic world. During his reign, Samarkand became one of the world centers of science.

Main scientific works

Ulugh Beg’s main area of interest in science was astronomy. In 1428 the construction of the Ulugh Beg observatory was completed. Its main mechanism was the quadrant with a radius of 40 meters, the only one of its kind in the world at the time. Ulugh Beg’s associates included prominent astronomers such as Qadi Zada al-Rumi, Ghiyath al-Din al-Kashi, and Ali Qushji.

Ulugh Beg’s main work in astronomy, Ziji Jadidi Guragani (New astronomical tables of Guragana) was in Persian and consisted mainly of the tables of coordinates of stars. The compilation of 1018 stars with high precision of spheric coordinates made hime famous initially in the Muslim world, and later (starting from the mid-17th century) in Europe and the whole world.
Contribution to world scientific heritage

First of all, his contribution to the world scientific heritage includes the catalogue of 1018 stars. The first star catalogue was compiled in the 2nd century B.C. by the ancient Greek astronomer, Hipparchus. Later astronomers introduced amendments to Hipparchus’ catalogue without performing original observations. By the beginning of the 15th century discrepancies between the actual position of the stars in the sky and their coordinates became significant, and Ulugh Beg decided to conduct his own measurements of the coordinates of stars. Thus, his table became the first catalogue after Hipparchus (i.e. 16 centuries later!) that was obtained on the basis of original astronomical measurements. This is the enduring scientific value Ulugh Beg’s Zij.

Contribution to mathematics

The core text of Ulugh Beg’s main work “New astronomical tables of Guragana” begins with trigonometric tables of very high accuracy. The table of sines is compiled with an increment of one minute, the table of tangents – in the range of 1-45 degrees with an increment of one minute, in the range of 45-90 degrees – with an increment of 5 minutes. The values are given to Quint 60-ary number system, which gives 7 to 12 correct digits in terms of the decimal system, i.e. the tables are compiled with the precision to 10–7–10–12.

In order to find the value of sin1° with great precision, Ulugh Beg, together with his colleagues developed a method of successive approximations , as set forth in his treatise “On the computation of the sine of one degree.”

In order to formulate the astronomical tables, which required the calculation of trigonometric functions and the coordinates of the stars with the abovementioned accuracy in a very large quantity, Ulugh Beg set up a research center, which became a prototype for the modern data centers.

International recognition

Ulugh Beg’s name is a symbol of selfless service in the name of science. In the mid-17th century a reknown Polish astronomer Hevelius included Ulugh Beg’s catalogue in his Astronomy: Beginning. He supplied his work with two illustrations, in which Ulugh Beg is pictured along with prominent astronomers of the world of different times. These illustrations are included in textbooks on astronomy and treatises on the history of science. They have become the invaluable relics commemorating the astronomical school of Ulugh Beg. His name is commemorated in the name of a crater on the Moon (17th century). One of the minor planets of the solar system, discovered in 1977 and registered by the Harvard Center under the registry number of 2439, was named after him.

According to the decrees of the President of Uzbekistan Islam Karimov National University of Uzbekistan and the Astronomical Institute of the Academy of Sciences of the Republic of Uzbekistan are named after Ulugh Beg. In 2004, during the official visit of the President of Uzbekistan to Latvia a monument of Mirza Ulugh Beg was officially opened in Riga.