The Koenigsberg Observatory was built in 1813, and was destroyed in 1944 during the Second World War. In this observatory Friedrich Wilhelm Bessel measured the parallax - and thus the distance - of a star for the first time in the world.

Koenigsberg - now Kaliningrad, part of Russia- was the part of the Prussian kingdom at the time of the foundation of the observatory. The Prussian government began the planning of the observatory in 1809 during the Napoleonic wars. In this year the astronomer Friedrich Wilhelm Bessel was invited from the observatory Lilienthal to Koenigsberg, to teach at the University and to take over the management of the planned observatory. As Bessel arrived to Königsberg in 1810, the observatory was still in the planning phase. First Bessel had to locate a suitable area with a clear view of horizon for the observatory. Finally he found it north-west to the city on the Butterberg near the fortress ramparts. The construction begun in 1811, taking into account Bessel's wishes. In September 1813 the Koenigsberg Observatory was completed.

In 1829, Bessel bought a heliometer from Fraunhofer's company, an equipment to measure small angle distances, usually used to measure double stars. Bessel, however, used it to measure the angular separations of the stars in the constellation Cygnus from each other. Because the stars are in different distances from us, they have different parallaxes. In 1838 as a result of this multi-year measurement series he succeeded to determine the 1/3 degree parallax of 61 Cygni. The result was of great importance, because on the one hand it showed that the stars were enormous distances compared to the size of Earth's orbit, on the other hand it gave a new proof of the Copernican system, and thirdly because it gave a cosmic measuring scale to the hands of mankind. For distance measurement in astronomy this method is still used nowadays. Bessel twice received the most prestigious honor, the Gold Medal of the Royal Astronomical Society in 1829 and in 1841. In 1842 he also got the Kingdom of Prussia's highest award, the Pour le Mérite.  Increases the importance of this achievement that it was not granted to civilians before 1842, only to soldiers.

Konigsberg 1 reverseKonigsberg 1 obverse

The now nonexisting observatory and Bessel is commemorated on a large, 120 mm diameter cast bronze medal made by medalist Ernst Schomer (1915-2005) in 1984. This year was the bicentennial of the birth of Bessel. On the obverse of the medal half-right facing portrait Bessel is shown. On the left birth and death years, on the right Bessel's autograph is placed. Beneath the artist's initials. On the reverse the observatory's building is located in front of the stars and waning moon background. Below that two year numbers 1874 and 1984 are visible.