The famous Russian astronomer Alexander Nikolaevich Deutsch was born in the night from 31 December 1899 to 1 January 1900 in Reni (Bessarabia), in a family of a lieutenant of the Russian Old army. His grandmother was of Romanian origin. Alexander learned at the I-st gymnasium in Saratov since 1909, which he finished in 1917. In 1917 he was admitted to the faculty of mathematics and mechanics of the Sankt-Petersburg University which He finished in 1923. He begun his scientific activity in 1922 as a calculator at the State Optical Institute in Sankt-Petersburg, then, after the finishing of the University, He was engaged as calculator at the Pulkovo Observatory. Subsequently he was assistant, scientific researcher, scientific specialist and senior scientific researcher in 1938 and concomitantly the Deputy Director of the Pulkovo Observatory.
In 1941-1942, which was the most difficult in the history of Pulkovo, Deutsch was the Director of the Observatory. Due to his efforts the Glass and Scientific Library of the Observatory were saved from destroy during the blockade of Leningrad.
The first scientific advisor of Alexander Deutsch was Sergey K. Kostinskii. His first scientific paper was concerned to the determination of the positions and brightness of the asteroid Ceres in 1923. Since that year he published more than 120 papers.
In 1935 he became Candidate of Physical and Mathematical sciences. The most important scientific contributions by Deutsch were the determination of the proper motions of stars in selected Kapteyn surfaces. As a result, he completed and defended in 1941 his Ph. D. thesis. The work by Deutsch concerned to mass determination of the dark satellite of 61 Cygni is widely known everywhere. A 40-year long work, which was begun by S. K. Kostinskii, showed that the rotation period of the small companion of 61 Cygni is 4.8 years and its mass is 0.008 solar masses. Another important work by Deutsch was the determination of absolute proper motions of stars. A. N. Deutsch participated in solar eclipse observations (1927, 1936, 1945). He participated in the longitude determination of Tbilisi and Sverdlovsk (actual Ekaterinburg) in 1930, and Arhangelsk in 1932. Due to his efforts the department of Astrometry and Stellar Astronomy was created in 1945. He conducted this Department till 1973. Deutsch can be considered one of the founders of the Soviet astrophotography school.
A. N. Deutsch taught Astronomy and Mathematics in the Universities of Leningrad and Tashkent. He became professor in 1947. Deutsch is one of the auteurs of the "Pulkovo course of Astrophysics and Stellar Astronomy".
Alexander Deutsch visited Romania in 1954, 1957, 1961. He participated in the IAU General Assemblies (1961, 1964, 1967). He was elected president of the IAU Commission 24 in 1961.
Alexandr Nikolaevich Deutsch died in 1986. The asteroid 1792 was named Reni in honour of Deutsch.
