The Effelsberg radio telescope is operated by the Max Planck Institute for Radio Astronomy in Bonn, the radio astronomy institute from the Max-Planck-Gesellschaft. It was constructed from 1968 to 1971 and inaugurated on 1 August 1972. A major technical difficulty in building a radio telescope of 100 m diameter was how to deal with the deformation as the – supposedly parabolic – mirror moves and tilts. The Finite element method was used to construct the mirror support in such a way that the deformed mirror will always take a parabolic shape. The focus will move during such deformation, and the receiver has to be moved accordingly. Tests after completion of the telescope showed that the intended accuracy of the mirror surface of 1 mm had not only been met, but exceeded significantly.
About 45% of the observing time is available to external astronomers. The Effelsberg 100-m telescope was involved in several surveys, including the one at 408 MHz (73 cm) by Haslam et al.[2][3]