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Abstract

Since joining INTERMANET in 2013, the Cheongyang Observatory(CYG) has been operated by the Korea Meteorological Administration. The CYG has continuously produced data observing the Earth's magnetic field. In order to improve and maintain quality of the proton magnetometer data, the magnetic field at the absolute measurement pillar was measured once a month using an optical pumping Cs-4He magnetometer, which is used as a magnetic field standard at the Korea Research Institute of Standards and Science. The 1-year average (2022) of the difference between the proton and Cs-4He magnetometer values at the absolute measurement pillar was –4.7 nT with a standard deviation of 0.2 nT. This kind of a comparison with a magnetic field standard, e.g., a Cs-4He magnetometer, operated on the basis of atomic magnetic resonance and verified through various ways for use as a standard, is necessary because the proton magnetometer typically measures the magnetic resonance of protons in kerosene samples. In the IAGA, the shielded proton gyromagnetic ratio, which is the proportional coefficient of the resonance frequency and magnetic field of the scalar proton magnetometer, is adopted from the CODATA and used. But the CODATA defines a pure water spherical sample, applying the value to a proton magnetometer using kerosene may cause a difference. In the conference, we will present an analysis of the comparison results between the two magnetometers including the temperature dependency.