Geoid and Lot Deviation Date 17.2.2009

Geoid: The geoid is defined by an area with constant gravity potential, which best corresponds to the mean sea level and the conceived continuation in the continental area. The mean sea level is determined by level observations (e.g. Amsterdam, Trieste). Geoidundulations: The distance of the geoid surface to a reference ellipsoid is called geoidundulation N. For Austria, the geoidundulations N were calculated in relation to the international ellipsoid GRS80 (reference system ETRS89) and the Bessel ellipsoid (reference system MGI): NGRS80 and NBessel Austrian geoid map: The Austrian geoid map shows in isoline representation the geoidundulations on the Austrian territory in two different representations: (a) Austrian Geoid Map GRS80: The geoidundulations NGRS80 show the distances of the geoide above the international ellipsoid model GRS80 (reference system ETRS89) in a range between ~42 m in the northeast and ~53 m in the Ötztal Alps. (B) Austrian Geoid Card MGI: The geoidundulations NBessel show the distances of the geoide above the Bessel ellipsoid (reference system MGI). The range of values lies between ~-2 m in the western Innviertel and ~ + 3.5 m in the Ötztal Alps or in East Tyrol. Solder deviation: The solder deviation is the angle between a geometrically defined ellipsoid normal and the physically defined solder direction at a point. It describes the direction of the heavy vector, shown in a north/south and an east/west component. For the entire territory of Austria, solder deviations – more precisely, surface lottering deviations – can be calculated and released in relation to the Bessel ellipsoid in the reference system MGI. Reference date = creation date: The data for this day are the most up-to-date database of the BEV. This is not identical with the recording or survey date.