The gravimeters generally possess the nonlinear 'zero reading' drift behaviour in time, which requires the establishment of a rather dense local reference network in the survey areas to minimize the drift effect.
Contemporary gravimeters were used and the detected correction (0.
Gravity determination by the IPE using the GABL absolute gravimeter in Tallinn in 1975 are quite well documented by Arnautov et al.
From 1970 to 1990 four gravity campaigns were carried out on the network by using a precise USSR manufactured spring gravimeter GAG-2.
Three points of the I order network were observed with a JILAg-5 absolute gravimeter by the FGI.
In 2006 a number of gravity points along the roads were surveyed with a Scintrex CG-5 gravimeter.
Perhaps future generations of absolute gravimeters will all measure g by dropping atoms (Fig.
Faller, A direct and sensitive method for positioning the center of mass of the dropping object at the optical centre of the enclosed corner cube in ballistic absolute gravimeters, Metrologia 41, L19-21 (2004).
Faller, Absolute gravimetry: Environmental noise limits, presented at Proceedings of the Workshop on Non Tidal Gravity Changes: Intercomparison between absolute and superconducting gravimeters, Walferdange, Luxemburg (1991) pp.
Faller, Continuous gravity observations using Joint Institute for Laboratory Astrophysics absolute gravimeters, J.
Klopping, A new generation of absolute gravimeters, Metrologia 32 (3), 159-180 (1995).
In the case of Artyom Vitouchkine's and my most recent absolute gravimeter , a cam-based instrument that will be described later, this co-placement of the center of mass and optical center must be done even more precisely.