Investigation on gPhone gravimeter-119 for gravity variations observation during the 10th International Comparison of Absolute Gravimeters (ICAG-2017)

The 10th International Comparison of Absolute Gravimeters (ICAG-2017) was held in Changping campus of National Institute of Metrology (NIM), China in October 2017. The observation of gravity variations using relative gravimeters plays an important role in absolute gravimeter comparison and the link of gravity reference value after comparison. We carried out a continuous observation of gPhone gravimeter-119 simultaneously alongside a superconductive gravimeter iGrav-012 for several months. The calibration factor of gPhone-119 is determined to be 0.99355±0.00004 with a precision of 0.004%. When the observation time exceeds 33000 minutes, the calibration values and uncertainties tend to be stable and the precision is better than 0.01%. The non-tidal gravity changes during ICAG-2017 recorded by gPhone-119 are analyzed. The tendency of gravity variations is roughly consistent with that recorded by iGrav-012. The result indicates that the peak-to-peak value of gravity changes is less than 1.5 μGal during the period of ICAG-2017.