Geomagnetic instrumentation for repeat station survey

Repeat station survey measurements are important geomagnetic data because they are widely used both for fundamental science (e. g., study of Earth's magnetic dynamo) and for applied purposes (e.g., declination charts for aviation safety). To execute repeat station surveys, normally three types of instruments are used: absolute scalar magnetometers, three-component vector variometers, and theodolite-mounted one-component magnetometers. The modem specifications of each rnagnetometer are described together with simplified fundamentals of their operation. The recommended set of such devices is given and possible further development of this type of instrumentation is discussed.