Brian Luck

Results of the European Comparison of Absolute Gravimeters in Walferdange (Luxembourg) of November 2007

The second international comparison of absolute gravimeters was held in Walferdange, Grand Duchy of Luxembourg, in November 2007, in which twenty absolute gravimeters took part. A short description of the data processing and adjustments will be presented here and will be followed by the presentation of the results. Two different methods were applied to estimate the relative offsets between the gravimeters. We show that the results are equivalent as the uncertainties of both adjustments overlap. The absolute gravity meters agree with one another with a standard deviation of 2 μgal (1 gal = 1 cm/s2).

Final report on the Seventh International Comparison of Absolute Gravimeters (ICAG 2005)

The Bureau International des Poids et Mesures (BIPM), S?vres, France, hosted the 7th International Comparison of Absolute Gravimeters (ICAG) and the associated Relative Gravity Campaign (RGC) from August to September 2005.ICAG 2005 was prepared and performed as a metrological pilot study, which aimed: To determine the gravity comparison reference values; To determine the offsets of the absolute gravimeters; and As a pilot study to accumulate experience for the CIPM Key Comparisons. This document presents a complete and extensive review of the technical protocol and data processing procedures. The 1st ICAG?RGC comparison was held at the BIPM in 1980?1981 and since then meetings have been organized every 4 years.In this paper, we present an overview of how the meeting was organized, the conditions of BIPM gravimetric sites, technical specifications, data processing strategy and an analysis of the final results. This 7th ICAG final report supersedes all previously published reports.Readings were obtained from participating instruments, 19 absolute gravimeters and 15 relative gravimeters. Precise levelling measurements were carried out and all measurements were performed on the BIPM micro-gravity network which was specifically designed for the comparison.

Results of the Seventh International Comparison of Absolute Gravimeters ICAG-2005 at the Bureau International des Poids et Mesures, Sèvres

The International Comparison of Absolute Gravimeters ICAG-2005 was held at the Bureau International des Poids et Mesures (BIPM), Sevres, France in September 2005. The organization of ICAG-2005, measurement strategy, calculation and presentation of the results were described in a technical protocol pre-developed to the comparison. Nineteen absolute gravimeters carried out 96 series of measurements of free-fall acceleration g at the sites of the BIPM gravity network. The vertical gravity gradients were measured by relative gravimeters. For the first time the budgets of uncertainties were presented.

Absolute Gravity Measurements in the Southern Indian Ocean

In March – April 2005, Absolute Gravity (AG) has been measured by the Strasbourg gravimetry team using gravimeter FG5#206 at 4 French scientific stations in the Indian Ocean. Crozet, Kerguelen and Amsterdam are isolated Islands located approximately 3000 km south of La Reunion Island. Four times a year, the multi-purpose ship Marion-Dufresne II connects them to La Reunion. Measurements were taken at Crozet from 8 to 10 March, Kerguelen from 14 to 18 March, and Amsterdam from 20 to 24 March. Moreover AG was measured at the Volcanic Observatory of the Piton de la Fournaise, La Reunion Island, from 31 March to 4 April.