English: Gravitational wave signal GW170817 measured by the LIGO and VIRGO gravitational wave detectors, plotted as a function of frequency and time. The chirp produced by the neutron star merger is clearly visible as a thin line curving upwards in the LIGO-Hanford and LIGO-Livingston data. The event is not visible in the VIRGO data, due to the lower sensitivity of the VIRGO detector, and the orientation of the detector with respect to the incoming gravitational waves.