English: This Picture of the Week shows a long exposure image of the BlackGEM telescopes, located at ESO’s La Silla Observatory in Chile. The whitish star trails in the sky are an effect due to the Earth’s rotation on its axis around the southern celestial pole, which gives the impression of the stars’ movement over the course of several hours. To the right hand side of the central telescope the Milky Way is visible, seen here as a particularly bright region, densely packed with streaks of starlight. As these streaks move in circles across the night sky, the viewer gets a sense of tumbling around inside a giant washing machine, as they peer out at the scene through the fisheye lens.BlackGEM, which recently started operating, is an array of three 0.65-metre optical telescopes, which can point at different regions of the sky, searching for some of the most dramatic events in the Universe like merging neutron stars and black holes. As these events unfold they send out ripples in spacetime, known as gravitational waves, which can be picked up by observatories like LIGO and Virgo. BlackGEM can then pinpoint the light sources from the afterglow of these events, allowing for more detailed follow-up observations of these cataclysmic collisions.