Swedish Radio Astronomy

Swedish radio astronomy and its development are synonymous with the formation and development of the Onsala Space Observatory at Chalmers University of Technology. The observatory grew out of the ionospheric research activities of prof. Olof Rydbeck, and his subsequent interest in radio astronomy that was stimulated during his years in the US. The increasing problems with radio interference in the Gothenburg area, eventually led to a donation of land on the Onsala peninsula, which made it possible to create a radio astronomical observatory in the late 1940:ies. This was a time when funding for research infrastructure was not easily obtained, and the first significant step came when the observatory bought five German second-world-war radar antennas (7.5 m Würzburg Riese) from Norway and brought them to the Onsala site. This made it possible to start mapping cosmic hydrogen, through the 21 cm line, in our galaxy, the Milky Way, and also to perform solar observations. The observatory was officially inaugurated in 1955, and Fig. 1 shows the installations in the late 1950:ies.