Surveying the gravitational wave sky

Gravitational waves were predicted 99 year ago by Albert Einstein as a
consequence of General Relativity. Even though their emission has been
confirmed in a few compact star binary systems, up to now they eluded
our direct detection. Upgraded observatories for gravitational waves
will resume to survey the sky at unprecedented sensitivities. We will
give a brief overview of the challenges of these observations and of the
new opportunities for astrophysics.