VLT telescope. Antu, also called Unit 1 (UT1), is one of four 8.2-metre mirror telescopes making up the Very Large Telescope (VLT) at Paranal Observatory in Cerro Paranal, Chile. The others are Kueyen, Melipal and Yepun (UT2, UT3 and UT4 respectively). At top is the secondary (M2) mirror unit, at upper centre is the unit for the primary (M1) and tertiary (M3) mirrors, and at bottom is the Cassegrain focusing instrument (which is called FORS1 in Antu). The mirrors are flexible and are constantly adjusted by computers to compensate for errors. The images from the four telescopes are combined by interferometer to produce an image equal to that obtained by one 16 metre diameter mirror. This makes the VLT one of the most powerful telescopes in the world.