Virgo Logbook

As a first attempt to study the etalon effect of the new input mirrors, we changed the correction sent to the heating-belts that were recently installed at the bottom flange of the input towers. In this way, the temperature of the mirrors can be changed without changing the thermal lensing as a side-effect, which would happen when changing the mirror temperature with the TCS.

The correction of the NI was decreased from around 2 to 0 units, while that of the WI was increased from around 2 to 8 units. This should hopefully allow to unambigously identify the mirror modes using Michele's technique. The thermal transient should last a bit more than a day. So far, the only collateral effect seems to be a drift of 3 urad of the WI local control system, which is small enough to be compensated by the drift control.