Advanced Virgo and the two Advanced LIGO detectors resume the taking of science data on the 1st of November, 2019, following a one-month-long stop. This event marks the restart of the third observation period, named O3, which started on the 1st of April, 2019. All three of the interferometers in the global gravitational-wave observatory paused O3 on the 1st October, 2019, in order to work on improvements to enhance the performance of the detectors.
On the Virgo side, the focus was on increasing the laser power injected into the interferometer, from 19 W to 26 W. This increase has been effective in improving the detector sensitivity at high frequencies, but has required a complete re-tuning of the interferometer.
Effort was also devoted to the study of selected noise sources. The lessons learned will be useful for the future operation of the instrument.