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Since its earliest beginnings in 1932 radio astronomy
has developed
into
one of the most important means of investigating the Universe. An
impressive
confirmation of this statement is given in the fact that most of the
observing
astronomers who received a Nobel
prize
in physics were working in the field of radio astronomy. This happened
in 1974,
in 1978,
and for the last time in 1993.
Electromagnetic radiation in the radio
wavelength
range from 0.35 mm up to about 15 m, which continuously hits the
Earth
from outer space, can be received using special aerials like the 100-m radio
telescope.
100-m Radio Telescope
Effelsberg
In this regard the large
aperture
of the dish of about 7850m² is important for the detection of the
extremely weak radio signals, while the large diameter of 100m is the
reason
for a comparatively high angular resolution, i.e. the smallest distance
on the sky at which two different objects can be detected separately.
At
1.3cm radio wavelength this resolution is 35 arc seconds, about
80stwice as good as that of the human eye at optical wavelengths.
The radio telescope rotates on a circular
track of 64m diameter which rests on a solid concrete foundation.
The
total weight of the steel structure is 3200 tons. Within about 12
minutes
the telescope can be turned through 360° horizontally, and the dish
can be tipped by 90° in less than 6 minutes. Thus, practically the
whole Sky above the horizon can be scanned.
The 100m telescope
in Effelsberg
went into operation already in 1972. Yet, even today it is still one of
the two largest
fully steerable parabolic antennas in the world. It can be used to
observe
the radio emission from objects in the Sky in the wavelength range from
90cm down to 3.5mm. 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 at
most
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.
100-m Radio Telescope:
Surface and Receiver Cabins
The receiver systems
for astronomical
radio radiation have horn aerials connected to extremely sensitive
cooled
low-noise amplifiers. These are mounted at the focal
point of the main reflector just beneath the prime focus cabin
suspended
on four support legs. Alternatively, an elliptically curved second
reflector
in the
path of rays
can focus the incoming radiation towards the central point of the
surface.
There, in the secondary focus cabin,
it
is possible to use many additional receiver systems, some even
simultaneously.
The equipment used to record, process and store the signals, as well as
the computers which control the telescope drives and the data
collection
are installed in the control room building up the hill.
The total project costs of about 34 million DM were
essentially covered
by a foundation (Volkswagen-Stiftung).
Additional financing was provided by the state of Nordrhine-Westfalia
and the Max-Planck-Gesellschaft.
The federal ministery for science and technology (Bundesministerium
für Bildung und Forschung paid for
some special parts of the equipment.
Technical Data
of the Effelsberg Radio
Telescope
| Reflector Diameter |
100 m |
| Aperture |
7,850 m² |
| Number of Surface Elements (Panels) |
2,352 |
| Shape Accuracy of Surface |
< 0.5 mm |
| Focal Length in Prime Focus |
30 m |
| Secondary Mirror Diameter
(Gregory-Reflector) |
6.5 m |
| Aperture Stop |
|
| - in Prime Focus |
f/0.3 |
| - in Secondary Focus |
f/3.85 |
| Angular Resolution (Beam Width) |
|
| - at 21cm wavelength (1.4 GHz) |
9.4' (arc minutes) |
| - at 3cm wavelength (10 GHz) |
1.15' (arc minutes) |
| - at 3.5mm wavelength (86 GHz) |
10" (arc seconds) |
| Azimuth Track Diameter |
64 m |
| Setting Accuracy of Track |
+/- 0.25 mm |
| Azimuth Range |
480° |
| Maximum Rotation Speed |
32°/min. |
| Power Output of the 16 Azimuth-Drives |
17.5 kW each |
| Radius of Elevation Gear Track |
28 m |
| Elevation Movement |
from 7° to 94° |
| Maximum Tilt Speed |
16°/min. |
| Power Output of the 4 Elevation-Drives |
17.5 kW each |
| Total Weight |
3,200 t |
| Construction Period |
1968-1971 |
| Height of Track above Sea Level |
319m |
| Commencement of Operation |
August 1st, 1972 |
| Constructed by |
Arbeitsgemeinschaft KRUPP/MAN |
|
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Last modified by njn on Friday, September 2nd, 2005
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