Revista Brasileira de Cartografia (Nov 2009)
THE CAPACITY OF THE SCINTREX AUTOGRAV CG-3M NO. 4492 GRAVIMETER FOR "ABSOLUTE-SCALE" SURVEYS
Abstract
In autumn 2001, the Institut für Erdmessung (IfE), received the new Scintrex Autograv CG-3M spring gravimeter no. 4492 (SC-4492). Compared with LaCoste-Romberg gravimeters, the Scintrex instrument offers the advantage of a more simple calibration function. Due to the straightforward sensor design (no micrometer screws and gearboxes, no astatisation), a modelling of periodical calibration terms and of a higher order polynomial calibration function is not required. The costly calibration measurements can be reduced to some relative observations between two reliable absolute gravity stations. No complex calibration system should be necessary. A reliable evaluation of the SC-4492 was done with respect to the stability of the calibration, measurement accuracy and precision, drift behaviour, and gravity range dependency of the calibration factor. Measurements were performed on the Hannover vertical calibration line (200 μm/s2 (20 mGal) range, 20-storied building, 10 μm/s2 interval), on the Cuxhaven-Harz north-south line (3000 μm/s2 range, 34 stations, 90 μm/s2 interval) of the gravimeter calibration system Hannover, and in the absolute gravimetry net of the Fennoscandian land uplift area (6200 μm/s2 range). A total gravity range of almost 0.015 m/s2 has been covered. In addition, the gravimeter was employed in the determination of vertical gravity gradients and centring to safety points for absolute gravimetry, and the observation of the horizontal gradient field at the IfE absolute gravity reference station in Clausthal. This paper presents the results as obtained in regional, local and microgravimetric surveys. The achieved accuracies are in the order of ±10 to 100 nm/s2 (±1 to 10 μGal). No instability of the calibration and no gravity range dependency could be proven within the order of 1·10-4. Overall, the gravity meter SC-4492 meets fully the expectations of IfE.
