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Abstract

DI-Flux instruments used for absolutely determining the Earth's magnetic field components consist of a non-magnetic theodolite usually equipped with a single axis fluxgate sensor. Nowadays, particularly as a heritage of space missions, three component fluxgate sensors are available small enough to fit on the telescope of a theodolite and able to measure the Earth magnetic field with an adequate linearity. One can presume that the additional magnetic information should contribute to an improved measurement result. Performing the standard procedure of declination and inclination readings, respectively, in the 4 possible orientations of the sensor, allows to calibrate and align the fluxgate sensor completely. Each of the angle readings provides the complete field vector in the geographic reference system which leads us to a welcome redundancy. By this redundancy, inaccuracies in leveling the sensor for the declination measurements, imprecise readings of the angles and systematic effects due to field gradients can be taken into account during data processing. This should relax the very high requirements for precision in the measurement procedure with a one-component sensor. Such a simplification of absolute measurements is highly desirable for observatories without permanent, well-trained staff where semi-skilled laypersons are doing the observations. We present the underlying calculations and first results obtained at Niemegk observatory.