International service for earth rotation and reference systems
The International Service for Earth Rotation and Reference Systems (acronym IERS ; English International Earth Rotation and Reference Systems Service formerly only; International Earth Rotation , Eng. International Earth Rotation Service is) an international organization to measure and calculate the Earth rotation parameter and a reference system for astronomy and geographic position data.
The earth rotation service is operated by international organizations of geodesy and astronomy and processes all geodetic measurements to artificial earth satellites and quasars in order to continuously calculate the position of the earth in the fundamental astronomical system .
From International Broad Service to IERS
It was founded in 1899 - a few years after the discovery of the terrestrial polar movement - by Theodor Albrecht , Wilhelm Foerster and Friedrich R. Helmert in Berlin as an International Broad Service . From an observation point of view, it comprised 5 globally distributed fundamental stations , all of which were located on the same latitude of 39 ° 08 ′, in order to be able to detect the smallest changes in latitude by observing star passages using the Horrebow-Talcott method .
Since the 1970s, this visual-astrometric measuring method was supplemented by the automatic method of satellite geodesy and later replaced. This increased the measurement accuracy tenfold. The data are combined every few years to form earth models that are now centimeter-accurate , see IERS Terrestrial Reference System (ITRS) and ITRF 2000. When the automatic measurement was introduced, the central office of the IERS was in Washington (USA) and Ōshū (Japan). Today it is back in Germany ( Frankfurt am Main ).
The IERS measurements also help calculate Coordinated Universal Time (UTC), which is coordinated by the International Bureau of Weights and Measures (BIPM) in Paris. For example, based on the recommendations of the IERS, the BIPM uses leap seconds in the coordinated world time in order to maintain the closest possible correspondence with solar time .
Combination of several procedures
The following measurements in particular contribute to the IERS service:
- VLB interferometry with large radio telescopes to extragalactic radio sources (several hundred almost point-shaped quasars )
- GPS position determination from hundreds of satellite stations and with the related system GLONASS (in future also the European Galileo )
- Satellite laser ranging according to special laser satellites
- Measurements of around 50 DORIS type Doppler stations
- Radar - distance measurements from the PRARE system , which, despite its precision in the centimeter range, is small enough to equip non-geodetic satellites with it.
See also
literature
- J. Höpfner: The International Latitude Service – A Historical Review, From The Beginning To Its Foundation In 1899 And The Period Until 1922 . In: Surveys in geophysics . tape 21 , no. 5 , 2000, pp. 521-566 , doi : 10.1023 / A: 1006701327419 .