Report on the 1995 Table-Mountain International Absolute-Gravity-Meter Intercomparison

In 1995, the NOAA Table-Mountain-Gravity-Observatory (TMGO) hosted an international intercomparison for absolute gravimeters. The facility chosen for these observations alleviated environmental noise and gradient transfer problems that have degraded previous intercomparisons. Included in the intercomparison were three different types of gravimeters from seven different groups who measured over a three week period. The instrumentation involved in the experiment included two JILA-g [1], six FG5 [2] and one Ocean-Bottom (OBAGM) type systems. All observations were taken in the same laboratory on four isolated piers with vertical displacements of less than 80 cm and horizontal displacements of less than 10 meters. Maximum gravity transfers between piers were less than 4 microgal. The results show the standard deviation of all instrument’s observations to be 3 microgal while the FG5 instruments (101, 102, 104, 106, 107 and 111) compared at less than 1 microgal (1 microgal = 10−8 m/ s 2).