An Auxiliary Telescope among three giants in UHD

The central Auxiliary Telescope of the Very Large Telescope array (VLT) might look like a dwarf next to three Unit Telescopes, but its primary mirror measures a whole of 1.8 metres in diameter. Four of these Auxiliary Telescopes can be connected to the four Unit Telescopes to form the Very Large Telescope Interferometer (VLTI) at the Paranal Observatory. Furthermore, the Auxiliary Telescopes can move along tracks across the platform of the VLT and are self-contained.