The operator difference in absolute geomagnetic measurements

Absolute geomagnetic measurement is very important at geomagnetic observatories. It plays a decisive role in data quality control and instrument calibration. As absolute geomagnetic measurements from modern fluxgate theodolite instruments have high precision, usually within 1 arcsec, the measurement results are susceptible to external factors. The operator difference is one of these factors and has become an important consideration that can not be ignored with respect to measurement results. Therefore, an experiment was designed in order to estimate the operator difference. Six fluxgate theodolites were used and six observers who were proficient in absolute measurements were invited to participate. The observers took turns making absolute geomagnetic measurements, and the operator difference between the observers for each instrument was computed by comparing baseline values using statistical methods.