10:15 AM - 10:30 AM
[SGD01-06] Parallel observation with superconducting gravimeters TT70 #011 and iGrav #028 at Matsushiro, Japan (2016–2018)
Keywords:superconducting gravimeter, Matsushiro, instrumental drift
We made a parallel observation by means of two superconducting gravimeters, TT70 (#011) and iGrav (#028) at Matsushiro, Japan from May 2016 through July 2018, with the main purpose of characterizing the instrumental performance of the iGrav as well as training of its operator. In August 2017, the position and orientation of the iGrav were changed in the room, and at the same time the feedback control of iGrav was changed from Run to Medium Feedback.
Regarding long-term trends of the recordings, both gravimeters showed gravity increase in the two years of experiment. Difference between the recordings from the two gravimeters was very close to being linear with respect to time except just after the installation and the position change of iGrav. The linear rate of the difference was 10.7 µGal/year (in the first year) and 11.3 µGal/year (in the second year). Assuming that the rate of instrumental drift of the TT70 was about 18 µGal/year (gravity increasing), the drift rate of iGrav was about 7 µGal/year.
The fact that the difference between the two gravimeters was almost perfectly linear with respect to time implies that they produced almost identical gravity recordings of long-periodic gravity changes. Our result shows that the iGrav, sometimes regarded as a simplified version of the superconducting gravimeter, has a precision to 0.1 µGal in months and 0.01 µGal in days.
Regarding long-term trends of the recordings, both gravimeters showed gravity increase in the two years of experiment. Difference between the recordings from the two gravimeters was very close to being linear with respect to time except just after the installation and the position change of iGrav. The linear rate of the difference was 10.7 µGal/year (in the first year) and 11.3 µGal/year (in the second year). Assuming that the rate of instrumental drift of the TT70 was about 18 µGal/year (gravity increasing), the drift rate of iGrav was about 7 µGal/year.
The fact that the difference between the two gravimeters was almost perfectly linear with respect to time implies that they produced almost identical gravity recordings of long-periodic gravity changes. Our result shows that the iGrav, sometimes regarded as a simplified version of the superconducting gravimeter, has a precision to 0.1 µGal in months and 0.01 µGal in days.