Abstract
In order to investigate quantitatively the accuracy of geomagnetic daily variation recorded by the FGE magnetometer, we analyzed the stability and precision of some groups' baseline values continuously recorded one day at seven observatories in 2009. The results show that the standard deviation and variable amplitude of the baseline values are small in D, H, and Z components, the standard deviation values are δD≤0.03', δH≤0.3nT, δZ≤0.3nT respectively, and the variable amplitude values are ΔD≤|0.05'|, ΔH≤|0.5'|, ΔZ≤|0.5'| respectively. Then we selected the baseline values continuously recorded one day at CDP and KSH observatories in 2009 and 2010 and analyzed the influence of absolute measurement intervals on the stability of the baselines.