The German Gravity Base Net 1994 (DSGN 1994)

Abstract

On behalf of the German Geodetic Commission the Bundesamt für Kartographie und Geodäsie re-measured the German Gravity Base Net established in 1976. After the reunification of Germany this network has been extended to the new German Federal States so that in total the network comprises 30 stations with a mean distance of 200 to 250 km. Each station consists of a main point and two sub-centres. The observations were performed in 1994/95. All centres of the 30 stations have been measured with the absolute gravimeter FG5–101 of the Bundesamt für Kartographie und Geodäsie. At six selected stations the Institut für Erdmessung, Universität Hannover carried out absolute measurements with its absolute gravimeter JILAG-3.

Whereas in the old part of the network comparisons could be made to the adjustment results of 1976, relative gravity measurements were carried out in the new part of the network as an independent control. The relative gravity ties were measured with 3 LCR gravimeters with SRW feedback and one Scintrex gravimeter CGM3. To minimise instrumental effects the LCR gravimeters were installed into temperature controlled aluminium boxes. For the transport, station cars were used with special spring-suspended containers. The instrumental accuracy for the absolute measurements can be estimated with 10–30 nm/s² (1–3 μGal) mainly depending on the seismic noise (microseismisity or antropogenic noise sources) at the stations. For the relative measurements an accuracy of 30–60 nm/s² (3–6 μGal) can be stated.