Automatic Alignment system during the second science run of the Virgo interferometer

In this paper the performances of the Automatic Alignment sensing and control system in the Virgo gravitational wave detector, during the second scientific run from July 7th 2009 to January 8th 2010, are described. The accuracy of the angular control loops fulfills the original Virgo requirements, reaching the accuracy of a few nano-radians for the most critical angular degrees of freedom, and the control noise is below the Virgo design sensitivity in the whole detection band.

Research highlights► Virgo gravitational wave detector: optical and mechanical configuration. ► Angular control system (Automatic Alignment) configuration for VSR2. ► Angular control accuracy in the Virgo specifications. ► Angular control noise below the design sensitivity in all the detection band.