At the outset of January, a power failure caused some damage to the GEO control system.
Afterwards, some wires connecting the electrostatic actuators to the high-voltage amplifier touched each other causing short circuits and one of the mirrors was bearing electric charges which affected the electrostatic actuators.
The attempt to remove the charges by ultraviolet irradiation of the mirror or by increasing the pressure in the Central Cluster of the vacuum system did not work out well enough. The short circuits which resulted from the touching wires could be removed by rewiring the connections outside of the vacuum system.
We are now preparing for a maintenance period in February which includes the opening of the vacuum tanks to do some repair work.
At the same time, we use this opportunity to look for scattering sources which might affect the noise performance in the mid frequency range from 200 Hz to 1000 Hz.