ESPRESSO instrument achieves first light with all four Unit Telescopes

The ESPRESSO instrument on ESO’s Very Large Telescope in Chile has used the combined light of all four of the 8.2-metre Unit Telescopes for the first time. Combining light from the Unit Telescopes in this way makes the VLT the largest optical telescope in existence in terms of collecting area. This picture explains pictorially how four telescopes are combined into one.