Weighing black holes with GRAVITY+

This artist’s impression imagines the swirling material around a distant black hole, not to scale, above a real image of ESO’s Very Large Telescope Interferometer (VLTI) at Paranal in Chile. 

Using the VLTI, astronomers have, for the first time, made a direct measurement of the mass of a remote black hole, one so far away that light from its surroundings took 11 billion years to reach us. This distant measurement, presented in January 2024, was made possible thanks to the upgraded GRAVITY instrument, a part of a series of improvements on the VLTI called GRAVITY+.