Zooming in on the kilonova in NGC 4993

The sequence starts with a broad view of the night sky. We then zoom in towards the constellation of Hydra. This was the direction from which gravitational waves were detected by LIGO-Virgo on 17 August 2017. The blue region shows the large area in which the source was expected to lie. Once identified many ESO telescopes and instruments scrutinised the region around the galaxy NGC 4993, where a transient source had been spotted. These included VISTA, the VST, the GROND instrument on the MPG/ESO 2.2-metre telescope and VIMOS and other instruments on the VLT. The final sequence shows how VISTA monitored this source, a kilonova created by the merging of two neutron stars, as it brightened and then became must redder in colour and faded.