Abstract：FG5X-249 absolute gravimeter and iGrav-012 superconducting gravimeter were observed in the same period and site in Changping campus of National Institute of Metrology, China. The calibration factor of iGrav-012 superconducting gravimeter is calculated by the method of least squares regression analysis. The calculation results from observations during the year of 2014 to 2017 showed that the relative calibration factor accuracy of each year is better than 0.1%. When the drop numbers of FG5X-249 absolute gravimeter is more than 6000, the calibration factor can be stable. According to the analysis result the annual maximum variation is less than 0.6nm·s-2·V-1, so that calibration once a year can meet the requirements of accuracy. The iGrav-012 can be used as part of national metrologia reference standard of gravity measurement, provide the gravity variation with time link during the international key comparison of absolute gravimeters CCM.G-K2.2017 and be used for the traceability of absolute gravimeters after comparison.
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2019, Vol. 40 
