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Turkish National Magnetic Network (TUMA)
General Directorate of Mapping started magnetic field measurements in 1945. Main objective is to display the difference and direction between true north, grid north and magnetic north in a diagram at the bottom of the topographic maps. The annual change in magnetic declination is also given at the same diagram.
Turkish National Magnetic Network consists of 85 points nationwide. Network points had been resurveyed at 10 years intervals until 2000. Since General Directorate of Mapping agree to use the World Magnetic Model which is a NATO standard specified in STANAG 7172 (Use of Geomagnetic Models), at the moment we use World Magnetic Model but make magnetic declination measurements and mark compass roses (airport compass calibration pads) on demand.
In the field measurements FM300 vector magnetometer was used until 2000. Since then, a Bartington fluxgate magnetometer mounted on a non-magnetic theodolite has been using to measure magnetic declination just after determining the true north direction via GPS.
Turkish National Magnetic Network
Antimagnetic Teodolite and MAG-A prob