Virgo

A 3 km laser interferometerinterferometryCombining waves from separate receivers coherently. In radio and optical astronomy, correlating signals from separated telescopes gives the resolution of one as large as their separation. In gravitational-wave detection, a laser Michelson interferometer measures tiny differential changes in its arm lengths. with Fabry–Pérot arm cavities at Cascina, near Pisa, run by the European Gravitational Observatory. As a third site with a different orientation it turns the long arcs of a two-detector LIGO localisationsky localisationWhere on the sky a source probably lies, published as a HEALPix probability map; its size is quoted as the area containing 90% probability. Two detectors give long arcs of hundreds to thousands of deg²; a third and fourth detector shrink it by triangulation. into patches of tens of deg²square degreeUnit of solid angle: one degree by one degree on the sky. The whole sky is about 41,253 deg²; the full Moon covers about 0.2 deg²., as for GW170817.

Operator

EGO, CNRS, INFN, Nikhef

Site

Cascina, Italy

Frequency band

10 Hz – 5 kHz

Messenger

Gravitational waves

Joined observing (O2)

1 August 2017