Wilhelm Foerster led the observatory until the end of his life in 1903. It was his impulse that led to the erection of the Astrophysikalischen Observatoriums Potsdam in 1874 for on the Telegrafenberg in Potsdam. On the Telegrafenberg stood formerly the „Telegraphenstation 4 which given the hill its name. In the same year Foerster founded the Berlin Astronomische Rechen-Institut (as Rechen-Institut zur Herausgabe des Berliner Astronomischen Jahrbuchs), on the basis of the ever-growing extent of calculation of astronomical ephemerides, which occupied its own building at ″Lindenstraße 91″, but on the grounds and in association with the observatory. Most of the astronomers now worked in this theoretical section - separate from the practical, observational section. The section was led by Friedrich Tietjen, who had been working at the observatory since 1861. In 1865 he discovered the asteroid (86) Semele. After Tietjens death, Julius Bauschinger was called to Berlin in 1896 as his successor. In the following year he achieved in making the institute fully independent of the observatory. In 1912 it moved into a new building in Berlin-Lichterfelde. In 1944 it was placed under the control of the Navy and transferred to Sermuth in Saxony to avoid the bombing. After the Second World War the greater part was brought to Heidelberg in 1945. Only a small remaining section returned to the observatory, which by now had moved to Potsdam-Babelsberg and it was again incorporated in 1956.