Geodetic reference system 1980
The Geodetic Reference System 1980 ( GRS 80 , English Geodetic Reference System 1980 ) is an earth model that includes the most important parameters of the earth's shape , the earth's rotation and the gravitational field .
The reference ellipsoid of the GRS 80 serves the European spatial reference system ETRS89 as a geometrical calculation and mapping surface and with it forms the geodetic datum for uniform national surveying . The compliant UTM mapping is used as the mapping system. In Germany, the GaussKrüger coordinates related to the Bessel ellipsoid ( Potsdam date ) and the Krassowski ellipsoid ( Pulkovo date ) are converted to GRS80 and UTM.
GRS 80 also defines the normal gravity and thus replaces GRS 67 . WGS 84 practically uses the ellipsoid of the GRS 80 but contains more data about the gravitational field .
GRS 80 was adopted in 1979 at the general assembly of the IUGG , the international umbrella organization for geodesy and geophysics , and published in detail in 1980 by the head of the study group, Helmut Moritz , after consultation with the International Astronomical Union (IAU) .
The four defining geometric and physical parameters are:
Major semiaxis / equator radius  
Gravitational constant times earth mass (more precisely measurable than the individual factors) 

Difference in the main moments of inertia related to M _{⊕ }a ^{2} (without the influence of tidal forces ) 

Angular velocity (including information on the orientation of the axis of rotation and the prime meridian ) 
The derived parameters for describing the shape of the Earth's ellipsoid are:
Small semiaxis / pole halfaxis  
Parameters of Earth flattening 
See also
literature
 Bernhard Heckmann: Introduction of the ETRS89 / UTM position reference system when switching to ALKIS. In: Communications of the DVW HessenThüringen, 1/2005, p. 17 ff.
 Ralf Strehmel: Official reference system for the situation  ETRS89. Surveying Brandenburg, 1/1996 ( PDF ).
 Bernhard Heck: Calculation methods and evaluation models for national surveying. Karlsruhe 1987.
 HansGert Kahle : Introduction to Higher Geodesy . 2nd, revised and expanded edition. Verlag der Fachvereine, Zurich 1988.
 International Association of Geodesy (IAG): Geodesist's Handbook 1980.
Web links
 Helmut Moritz: Geodetic Reference System 1980 (MS Word document, if the formulas are not displayed: CtrlA AltF9; DOC file; 63 kB)