European Comparison of Absolute Gravimeters – ECAG2007

Walferdange, 6-9 November 2007

This page was last updated on: Thu, Sept. 06, 2007

The European Comparison of Absolute Gravimeters was held in Walferdange (Luxembourg) the 6-9 November 2007. In this circular, I would like to provide some practical information on the venue and on the protocol to be adopted for the comparsion.

  1. Many teams have shown interest in participating in the comparison (see the list of participants). We are expecting more than 20 absolute meters to take part.
  2. For practical reasons, we must request that the teams participating send a maximum of two people per instrument. For reasons of limited space, the comparison must be restricted to only people involved in the organizations or in operating an instrument. The Underground Laboratory is large but not large enough to accommodate “spectators”.
  3. During the comparison, we will try to organize independent teams to be in charge of calibrating the clocks and the barometers.
  4. For the vertical gravity gradient, Philippe Richard, Michel van Camp and myself made the measurements with their Scintrex in 2003. I will repeat all the measurements before the comparison. If anyone of you wishes, he is more than welcome to carry out vertical gravity measurements.

Venue, accomodation

The Comparison will be held at the Underground Laboratory for Geodynamics in Walferdange very close to the ECGS office building.

List of Participants

Name Instrument Affiliation
Francis FG5-216 University of Luxembourg/ECGS
Mclaughlin FG5-103 or FG5-222 Proudman Oceanographic Laboratory
Van Camp FG5-202 Royal Observatory of Belgium
Baumann FG5-209 METAS
Palinkas FG5-215 VUGTK
Timmen and Gitlein FG5-220 Leibniz Universität Hannover
Mäkinen FG5-221 Finnish Geodetic Institute
Pettersen FG5-226 University of Environmental and Life Sciences
Le Moigne FG5-228 CNRS – Géosciences Montpellier
Smith FG5-229 Natural Environnement Research Council
Walo and Olszak FG5-230 Institute of Geodesy and Geodetic Astronomy WUT
Engfeldt FG5-233 (a.k.a. "Greta") Geodetic Research Division, Lantmäteriet
Germak IMGC-02 Istituto Nazionale di Ricerca Metrologica (INRIM)
Rothleitner, Wang and Svitlov IOIP Absol. Gravimeter University Erlangen-Nuremberg
Christian JILAg6 Federal Office of Metrology and Surveying (BEV)
Reudink FG5-234 Faculty of Aerospace Engineering, DEOS/PSG
Bonvalot A10#014 IRD / BGI
Chongyang FG5-232 China Earthquake Administration (CEA)
Pujol FG5-211 and A10#006 National Geographic Institute of Spain
Falk and Wilmes FG5-101 or FG5-301 Bundesamt für Kartographie und Geodäsie
Bianco FG5-? Italian Space Agency

Local Organizing Committee

  • Prof. O. Francis
  • Mrs H. Tiour, secretary of the geophysics group at the University of Luxembourg
  • Mrs. Corine Galassi, ECGS secretary


The following protocol is proposed for acceptance by the participants of the comparison of absolute gravimeters:

  • Each absolute gravimeter will measure at 3 different markers.
  • The occupation time at each point will be at least 12 hours.
  • Operators accept to fill out a form describing all the instrumental characteristics of their instrument.
  • The participants at the Euromet Pilot Study will fill out the form for the uncertainty budget of their gravimeters prior the comparison. The other participants are encouraged to do the same. Feel free to contact Alessandro Germak ( for more information.
  • The clock and barometer of each instrument will be calibrated during the comparison by an independent team.
  • Once a team has completed their observations, a copy of the data and of the log sheet will be provided to the organizers on CD-Roms before departing from the site.
  • Olivier Francis will no more process all the absolute gravity data. Each team must provide their final results including the associated uncertainty within 2 weeks after the comparison (25th of November 2007) to O. Francis. He will then adjust the data and make a first evaluation of the results. If big discrepancies are found, the operators will be asked to verify their results. In a second step, the results will be presented to all the participants. Once all of them have agreed on the final results, a publication will be prepared by early 2008 to guarantee expedient reporting on the results.