This is a time-frequency representation (spectrogram) of the LIGO detectors data which combines both the LIGO-Hanford and LIGO-Livingston data coherently for the binary neutron star merger GW170817. On the horizontal axis time is shown, and on the vertical axis the frequency content of the data. In color code the strength of the signal is shown as a function of time and frequency. This is analogous to listening to the source and turning to face it. In this case your ears are the two LIGO detectors. Initally, we show the data with the gravitational-wave signal removed. We reveal the observed data in real time, accompanied by the audio presentation of the plotted data. The signal is so strong that we see that the track of GW170817 for nearly 30 seconds. An audible chirp can also be heard at 0:29 just before the merger time - but you have to listen closely.

Credit: Alex Nitz/Max Planck Institute for Gravitational Physics/LIGO