European date 1950

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The European date 1950 ( ED50 ) is a geodetic date in which the international surveying network of the Western European countries was calculated from 1950. This European network is a precise union of around 20 state triangulation networks in order to be able to extend them to the fundamentals of geosciences in the time of increasing international cooperation. It also played a role for some developing countries and global analysis. In North America it corresponds to the North American Datum (NAD).

It is based on the International Ellipsoid from 1924 (mostly named after the author John Fillmore Hayford ) and has the Helmert Tower on the Potsdam Telegrafenberg as its fundamental point . The ellipsoid is positioned relative to the earth in such a way that it touches the geoid in Potsdam . The reason for choosing this survey point was its relatively central location (for Western Europe, Scandinavia and Southern Europe). The occupation army of the USA supported this initiative (with additional specialist staff, computers, etc.) and saw it as an opportunity to get parts of the Eastern bloc to cooperate (which hardly happened, however). The choice of the Hayford ellipsoid instead of the Bessel ellipsoid - which would be better suited to the geoid in Europe - is related to the dominance of the USA after the Second World War , as well as to some plans to use the ED 50 later for other continents.

Two decades later, the ED 50 was expanded to become the ED 77 and the ED 79 . On the same basis, but with more recent measurements and taking into account the reduction due to plumbing deviation , the ED 79 surveying network has since been the most important data material for comparison with measurements from satellite geodesy . The ED 50 is still used for various maps , as a data basis programmed in GPS receivers and for coordinate transformations , but has made room for its successors and the WGS 84 for new projects .

Current

The following data is currently used:

International ITRS-2005 or ITRF-2005
Europe ETRS-89 or ETRF-89
simplified WGS 84

literature

  • Karl Ledersteger : Astronomical and Physical Geodesy . Volume V of the Jordan-Eggert-Kneissl series of books, Handbook of Surveying. J. B. Metzlersche Verlagsbuchhandlung, Stuttgart 1956/1969.
  • Manfred Spata: Transformation of Coordinates and Heights in Land Surveying, Part I: Theoretical Basics . Landesvermessungsamt Nordrhein-Westfalen (ed.), 2nd edition 1999, pp. 17-18.
  • Greg Miller: behind the lines. Seizing Hitler's Maps. In: Smithsonian, Nov. 2019, pp. 64-78.