Updating the Precise Gravity Network at the BIPM

Abstract

The goal of maintaining an accurate gravity network at the BIPM headquarters is twofold: firstly to support the International Comparison of Absolute Gravimeters (ICAG), and secondly to support the BIPM watt balance (WB) project, which aims at determining the Planck constant h or realizing a future new definition of the kilogram based on a fixed value of h. In addition the absolute gravity measurements, Relative Gravity Campaign (RGC) is organized as part of each ICAG.The BIPM gravity network is characterized by its small size, indoor laboratory conditions, three-dimensional structure, and large number of parallel absolute gravity determinations. Over the last 3 decades, repeated precise horizontal and vertical ties have been measured using relative and absolute gravimeters, and precision leveling has been undertaken regularly to monitor the deformation of the terrain. The ICAG is held every 4 years; the 8th ICAG took place in mid-2009 and for the first time, it was organized as a metrological key comparison as defined by the CIPM MRA. Its results will such constitute a precise and consistent gravity