Max-Planck-Institut fur Radioastronomie (MPIfR)

The Max-Planck-Institut fur Radioastronomie (MPIfR) was founded in 1967. The 100-m radio telescope was inaugurated in 1971 as the largest fully steerable single-dish radio telescope in the world (for almost 30 years). It is situated in a protected valley near Bad Münstereifel-Effelsberg. To this day it is the largest radio telescope in Europe.

During the last decade various major actions have successfully been undertaken to preserve the Effelsberg 100-m radio telescope as one of the most powerful radio astronomical instruments in the world: the replacement of the azimuth track after 25 years of operation, the purchase of new aluminium panels for the outer part of the main reflector, and the exchange of the azimuth gear boxes. Corrosion tests of the steel construction proved that pipes and welded seams are in good shape. Holographic measurements of the main reflector have shown a reasonable mean deviation of <0.5mm rms for the central 80m diameter surface.

The combination of the high surface accuracy of the dish and the construction principle of 'homologous distortion' enables observations at unprecedented high frequencies for such a large telescope. The telescope can be used to observe radio emission from celestial objects in a wavelength range from 73cm (408MHz) down to 3.5mm (86GHz). Observations at short wavelengths can be performed despite the flexing of the steel members of up to 10cm due to gravity. Because of a special support structure the deviation of the dish surface from the ideal parabolic form is less than 0.5mm. The shift in the focus position due to surface flexure accompanying the tilting of the dish is compensated by means of an electronic control mechanism.

The wide variety of observations with the 100-m radio telescope is made possible by a large number of receivers which can be used either in the primary or in the secondary (Gregorian) focus of the telescope. Together with a number of backends dedicated to different observing modes they provide excellent observing conditions for spectroscopic observations (atomic and molecular transitions in a wide frequency range), and also for high time-resolution (pulsar observations), mapping of extended areas of the Sky and participation in a number of interferometric networks (mm-VLBI, EVN, and Global VLBIetc.). DevelopmentBuilding and maintenance of receivers and backends is supported by technical divisions in the Bonn institute as well as on site in Effelsberg. They comprise high-frequency and digital research labs, a microwave lab and a correlator group for running and maintaining a the new Mark IV correlator for mm-VLBI research.

Over the last five years observations at short cm-wavelengths (1.3-2cm) and mm-wavelengths (3 and 9mm) have become more important for spectroscopic programmes as well as for VLBI.

Both types of receivers are regularly used e.g. for observations with the IRAM 30-m telescope at Pico Veleta. MPIfR astronomers are frequent users of the 30-m telescope and also of the IRAM interferometer on Plateau de Bure. Especially for spectroscopic investigations there arecorresponding observations with both, the Effelsberg and the Pico Veleta telescope in different wavelength regimes. In future, observations at mm-wavelengths will become even more important for an increasing number of scientific projects.

The MPIfR TNA contact is A. Kraus
akraus@mpifr-bonn.mpg.de

More information can be found on the MPIfR Homepage.