Verifying the precision of a new generation absolute gravimeter FG5 - Comparison with superconducting gravimeters and detection of oceanic loading tide

We carried out a several day experiment at two sites to verify the precision of the FG5 absolute gravimeter through collocation with superconducting gravimeters. We found 2 to 4 microgal diurnal/semidiurnal signals in the time series of absolute gravity measurements. These signals agreed well with theoretical ocean tide both in amplitude and in phase, demonstrating that the FG5's precision is better than 2 microgal. Furthermore, we found that the discrepancy between the FG5 measurements and the SG measurements is 1.3 to 1.5 microgal. These results verify that the FG5 is precise to 1 to 2 microgal.