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Abstract

A calibration facility for search coil magnetometers (SCMs) has been built at Niemegk Geomagnetic Observatory, GeoForschungsZentrum Potsdm. I describe hee the commissionng of this facility. The usable frequency range of 10 mHz-100 kHz enables calibration of all standard types of SCM. The homogeneity is 0.1% up to a diameter of 10 cm and up to a lenght of 2.5 m. Extensive test measurements showed broad agreement with theoretical calculations made before constuction. as part of the testing, all SCMs in the GFZ geophysical equipment pool were checked. Serveral devices showed serious malfunctions, emphasizing the value of such a calibration facility. The calibration coil has been designed to be largely automatic, enabling non-specialists to operate it after a brief period of instuction. It can also be adapted to test other types of sensos with little effort (for example, fluxgate magnetometers). As a result, the facility should be of broad use for external institutions to calibrate their instruments.