Ørsted Pre-Flight Magnetometer Calibration Mission

The compact spherical coil (CSC) vector-feedback magnetometer on the Danish Orsted geomagnetic mapping satellite underwent extensive calibrations and verifications prior to integration and launch. The theory of the 'thin shell' calibration procedure is introduced. Spherical harmonic modelling was developed and tested over several years and used for Orsted and other missions at test facilities in Europe, the United States and the Republic of South Africa. The verification of the test coil system using an Overhauser absolute scalar proton magnetometer is explained and the overall calibration results are given. The temperature calibrations are explained and reported on. The overall calibration model standard deviation is about 100 pT rms. Comparisons with the later in-flight calibrations show that, except for the unknown satellite offsets, an agreement within 4 nT was obtained. Finally an rf interference between the CSC and the Overhauser magnetometer is discussed, which may account for some of this discrepancy.

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