1. Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
2. Institute for Gravitational Wave Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom
3. Laser Interferometry and Gravitational Wave Astronomy, Max Planck Institute for Gravitational Physics, 30167 Hannover, Germany
4. LIGO Laboratory, California Institute of Technology, Pasadena, California 91125, USA