Geodetic Observatory Wettzell
The Geodetic Observatory Wettzell is located on the 616 m high Wagnerberg , west of the village Wettzell in the district of Cham in the Bavarian Forest .
tasks
It is operated by the Federal Agency for Cartography and Geodesy (BKG) together with the Technical University of Munich (TUM) for the purpose of earth measurements and is one of the most important geodetic observatories in the world today .
As an observation station, the Wettzell Observatory has the task of obtaining measurement data for the geodetic spatial methods VLBI , SLR , GNSS and DORIS . These data are used to implement global coordinate reference systems , which are the basis for numerous tasks in the field of geosciences (e.g. measurement of continental drift or sea level rise ), in space travel, but also in areas of everyday life (e.g. surveying, navigation) form. These global tasks can only be solved today through international cooperation. The activities such as observations, data flow, data analysis and the provision of results are coordinated by the international services of the IAG , e.g. B. the IERS , the IVS , the ILRS , the IGS and the IDS.
The Federal Georeference Data Act (BGeoRG) provides the legal basis for this.
Wettzell also supports the operation of the AGGO observatory in La Plata / Argentina with a dismountable 6-meter radio telescope and the 9-meter GARS O'Higgins radio telescope in the Antarctic .
Measurement equipment
All modern observation methods of satellite geodesy or cosmic geodesy and complementary measuring methods are combined on the approximately 300 by 150 meter area
- a laser telescope for distance measurements to satellites and the moon (WLRS)
- a laser telescope for high-resolution distance measurements to low-flying satellites (SOS-W)
- a 20 meter radio telescope for intercontinental VLBI measurements (RTW 20). This RT has been in operation since 1983 and records the most geodetic measurements in the world. It is involved in the European VLBI network .
- a twin system consisting of two 13-meter radio telescopes has been in operation since 2012. The two bowls can be moved quickly and thus allow more and different measurements. The systems are also for VLBI measurements (TTW-1 and TTW-2)
- several multi- GNSS receivers for continuous satellite measurements
- a highly precise time system with several atomic clocks and hydrogen measles as well as a fiber optic time distribution system with delay compensation
- a ring laser in an underground observatory to monitor the rotation of the earth . This 4 × 4 meter ring laser is a worldwide unique instrument and can detect deviations in the length of the day of up to 0.1 milliseconds. To protect against external influences and to maintain a constant temperature, it is located in an underground bunker.
- a transmission system for the French Doppler system DORIS
- a superconducting gravimeter
- Additional measuring devices for underground and atmosphere monitoring (seismometer, tilt meter, hydrological sensors, climate station, water vapor radiometer, temperature profiler, cloud detector)
- and facilities for administration and maintenance.
The reference points of the individual measuring systems are linked by a local survey network in order to obtain coordinate differences for a combination of the various methods. This property characterizes a geodetic fundamental station .
history
It was founded in 1970 near the former Iron Curtain to the former Czechoslovakia and the Air Defense Identification Zone , in order to have a night sky as dark as possible with little light pollution and with the Satellite and Lunar Laser Ranging (SLR or LLR) little consideration for air traffic to have to take.
The beginnings of the satellite observation station Wettzell go back to an early research project of the Technical University of Munich and the IfAG on optical observation and orbit determination of geodetic earth satellites. The then newly emerging field of satellite geodesy promised great advances in global earth measurements. The optical observations that were carried out up to the end of the 1970s include recordings of satellite passages with the Zeiss double astrograph and the Zeiss BMK 75 ballistic measuring chamber for satellite triangulation as well as observations with the circumzenital and the Danjon astrolabe for astronomical longitude and latitude determination .
In cooperation with the German Research and Research Institute for Aerospace (DFVLR, today DLR ), a first laser rangefinder system, consisting of an anti-aircraft gun and a ruby laser , was put into operation in Wettzell in 1972 . On April 8, 1973, the distance to a satellite ( GEOS -1) was measured for the first time in Germany with a laser . But only with the following, computer-tracked systems SRS (Satellite Ranging System, 1977–1991) and WLRS (Wettzell Laser Ranging System, since 1991) are high numbers of routine observations possible. With the WLRS, distances to the reflectors on the moon have also been measured ( Lunar Laser Ranging ).
In the mid-1970s, the station was expanded to include microwave measuring methods. Since 1974 Doppler measurements on satellites of the "Navy Navigational Satellite System" (NNSS or Transit ) have been carried out regularly to determine points in geodesy. The first measurements for the NAVSTAR GPS satellite navigation system were made in the test phase 1979–1981 with Wettzell as one of 4 tracking stations worldwide. The Doppler measurements ended in 1993 after the NNSS was replaced with the full expansion of GPS.
With the commissioning of a radio telescope in 1983, the satellite observation station became a fundamental geodesy station, where the various geodetic spatial methods VLBI , SLR and GNSS are combined in one place. Since 2012, the observatory has had two more so-called twin telescopes in order to keep pace with technical progress and increasing observation tasks.
Web links
- Geodetic Observatory Wettzell
- Information flyer on the Geodetic Observatory Wettzell
- Friends of the Geodetic Information Center Wettzell
Individual evidence
- ↑ Federal Georeference Data Act
- ↑ a b Geodetic Observatory Wettzell. Federal Agency for Cartography and Geodesy (BKG) and Technical University of Munich (TUM, November 30, 2017, accessed on March 10, 2019 .
- ↑ Fundamentalstation Wettzell - A geodetic observatory, in: Zeitschrift für Vermessungswesen, issue 132 (3), pp. 158–167.
- ^ The work of the Collaborative Research Center 78 Satellite Geodesy of the Technical University of Munich, published by: Bavarian Commission for International Earth Measurement, in: Astronomisch-Geodätische Arbeit, Hefte 32 (1974) to 48 (1986).
Coordinates: 49 ° 8 ′ 38 " N , 12 ° 52 ′ 45" E