September 2015 – Advanced LIGO detectors begin first observation run
On, Friday, September 18th 2015, the first official 'observing run' (O1) of the advanced LIGO detectors in the USA began when the clock struck 8 a.m. Pacific time. While this date marks the official start of data collection, both interferometers have been operating in engineering mode taking data for some weeks already as technicians, scientists, and engineers worked to refine the instrument to prepare it for official observation duties. The GEO600 gravitational-wave detector operated by German and UK institutions near Hannover, Germany, is taking data simultaneously with the LIGO detectors. O1 lasted until January 12th 2016.