On February 11th, 2016 announced the scientific collaboration of the laser interferometer LIGO, located in the USA, that they have successfully observed gravitational waves, which most likely originated from a merger of two black holes. The article in Physical Review Letters journals, describing this ground-breaking observation, is available for download at the link:
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.061102
Other materials about the history of observations of gravitational waves and about the operation and construction of LIGO detectors are available from the webpages of the LIGO Collaboration.
From the point of view of the Institute of Physics of the Czech Academy of Sciences, it is interesting to note that Dr Antonio Lucianetti from HiLASE worked in 2007-2009 at the LIGO Observatory in Livingstone in Louisiana in the U.S., where he gained a unique experience in the field of laser interferometry of gravitational waves.