Effelsberg 100-m Radio Telescope

The telescope is located about 1.3 km northeast of Effelsberg, a southeastern part of the town of Bad Münstereifel in North Rhine-Westphalia. It is less than west of the high Hünerberg, which is in neighbouring Rhineland-Palatinate. The boundary is a stream, the Effelsberger Bach, which runs only a few metres east of the telescope. The Effelsberger Bach is long, flowing from the Effelsberger Wald into the Sahrbach, which in turn flows south and into the Ahr river. A hiking path leads past the telescope; in 2004 part of this was turned into a planet trail with information panels about the Solar System with its planets. The trail ends at the model of the Sun next to the visitor centre.

The Effelsberg radio telescope is operated by the Max Planck Institute for Radio Astronomy in Bonn, the radio astronomy institute of 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 diameter was how to deal with the deformation of the mirror due to gravity when it is rotated to point in a different direction. The mirror must have a precise parabolic shape to focus the radio waves, but a conventionally-designed dish of this size would sag slightly when rotated so the mirror loses its parabolic shape. The Effelsberg telescope uses a novel computer-designed mirror support structure which deforms in such a way that the deformed mirror will always take a parabolic shape. The focus will move during such deformation, and the feed antenna suspended in front of the mirror is moved slightly by the computer control system as the telescope is rotated to keep it at the focus. Tests after completion of the telescope showed that the intended accuracy of the mirror surface of had not only been met, but exceeded significantly. About 45% of the observing time is available to external astronomers. The Effelsberg 100-metre telescope was involved in several surveys, including the one at by Haslam et al. Technical data of the Effelsberg 100-metre Radio Telescope • Parameter — Value • Reflector Diameter — 100 m • Aperture • Number of Surface Elements (Panels) — 2,352 • Shape Accuracy of Surface • Focal Length in Prime Focus • Secondary Mirror Diameter (Gregory-Reflector) • Aperture Stop • in Prime Focus • in Secondary Focus • Angular Resolution (Beam Width) • at wavelength • at wavelength • at wavelength • Azimuth Track Diameter • Setting Accuracy of Track • Azimuth Range • Maximum Rotation Speed • Pointing Accuracy • Blind Pointing • Repeatability • Power Output of the 16 Azimuth Drives, each • Radius of Elevation Gear Track • Elevation Range • during observations • Maximum Tilt Speed • Power Output of the 4 Elevation Drives, each • Total Weight • Construction Period — 1968–1971 • Height of Track above Sea Level • Commencement of Operation — 1 August 1972 • Constructed by — Arbeitsgemeinschaft Krupp/MAN