Evolution and obtained expertise in reference point determination at the GIK
M. Lösler and C. Eschelbach 
Geodetic Institute/Universität Karlsruhe, Germany

Poster

The International Terrestrial Reference System (ITRS) is realized by geodetic space techniques, which are linked by local-ties at co-location stations. Therefore, reliability and high accuracy are the main requirements for the determination of the different reference points in the corresponding local reference frame. At the Geodetic Institute of the Universität Karlsruhe several scientific studies were carried out to determine the reference point of radio telescopes at different observation stations and with different calculation models. Starting in 2002 the IVS reference point at Onsala Space Observatory was determined by the fitting of 3d-circles with error propagation using full covariance information, which is custom procedure nowadays. In 2008 a completely new mathematical model was established, able to fulfill future requirements as for example minimizing shot-down-time of the telescope. Geodetic measurements with a tachymeter respectively a laser tracker at the Fundamentalstation Wettzell and the Onsala Space Observatory yielded a good verification of the model. 
This contribution shows the evolution and obtained expertise in reference point determination at the Geodetic Institute of the Universität Karlsruhe by comparing the results of different campaigns at the Onsala Space Observatory.