Astrophysical Observatory Potsdam, Potsdam

The Astrophysical Observatory Potsdam, originally part of the Berlin Observatory, was relocated from Berlin to Babelsberg in the early 20th century due to unfavorable observational conditions caused by urban development. The initiative for the relocation was led by Wilhelm Foerster, who appointed Karl Hermann Struve, the former director of the Königsberg Observatory, to oversee the move.

In 1906, after test observations by Paul Guthnick, a new site was selected on a hill in the eastern part of the Royal Park of Babelsberg, provided free of charge by the crown. The construction of the new observatory began in June 1911, and by August 2, 1913, the relocation from Berlin to Babelsberg was completed. The project, funded by the sale of the Berlin Observatory's property, cost 1.5 million Goldmark.

The first instruments arrived in 1914, including a 65-centimeter refractor telescope, the first major instrument manufactured by Carl Zeiss Jena, and a 122-centimeter reflector telescope, which was completed in 1924 after delays caused by World War I. The Babelsberg Observatory became one of the best-equipped observatories in Europe, and the 122-centimeter telescope was, at the time, the second largest in the world.

Under the leadership of Paul Guthnick, who succeeded Struve in 1920, the observatory became renowned for its advancements in photoelectric photometry, a pioneering method for measuring star brightness. The observatory gained international recognition for its spectroscopic investigations and studies of variable stars.

In 1931, the Sonneberg Observatory, founded by Cuno Hoffmeister, was attached to the Babelsberg Observatory. This partnership led to a significant photographic sky survey that spanned over 60 years and produced the second-largest archive of astronomical photographic plates, further enhancing the observatory’s global reputation.