The A.T. team

At the Very Large Telescope the Unit Telescopes may be the stars of the show, but the smaller 1.8-metre Auxiliary Telescopes are key supporting players. Their role is to assist when the VLT is being used for interferometric observations, in which multiple Unit Telescopes combine to act, in effect, as one larger telescope. In interferometric observations the resolution achieved is defined by the largest separation between the telescopes being used. While the large UTs cannot be used, the ATs can and are rearranged to create different virtual telescopes with different characteristics. Without these remarkably movable telescopes, the VLT would have far fewer options for interferometry, limiting its capabilities significantly.