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GEODEETTINEN LAITOS |
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14.01.2003 kirjasto@fgi.fi |
SUOMEN GEODEETTISEN LAITOKSEN JULKAISUJA |
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| REMEASUREMENT OF THE GÖDÖLLÖ STANDARD BASELINE by Jokela J., M. Poutanen, Zs. Nemeth and G. Virag Abstract The 864-m Gödöllö Standard Baseline in Hungary was first measured in 1987, half with the Väisälä interference comparator, and doubled with high-precision EDM. To confirm the stability of the baseline, it was remeasured in 1999. Both measurements were carried out in cooperation between the Finnish Geodetic Institute and the Hungarian Institute of Geodesy, Cartography and Remote Sensing. Between the two interference measurements it has been controlled once or twice per year by EDM. The scale of the measurements is based on the quartz gauge system used in the Väisälä interference comparator and is traceable to the definition of the metre. Results from new absolute calibrations and comparisons of quartz gauges were available. After four weeks of unfavourable weather conditions several successful interference measurements were finally performed up to 432 m. A Kern Mekometer ME5000 was used for the EDM. In all the measurements the accuracy obtained was by all accounts good. The results confirm the good stability of the baseline. The lengths between the most accurate benchmarks, the underground markers, have remained unchanged during the 12-year period. All the changes between the auxiliary markers used in calibration measurements are smaller than 0.5 mm and controllable with repeated check measurements. The Gödöllö Standard Baseline is well suited for calibration of most geodetic length measurement instruments. |
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14.01.2003 kirjasto@fgi.fi |
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| Geodeettinen laitos Geodeetinrinne 2, PL 15 02431 MASALA |
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: (09) 2955 50