VLT Auxiliary Telescopes

The Sun has just set at ESO Paranal Observatory and the VLT Auxiliary Telescopes (ATs) are about to open and start observations for the night. The ESO Very Large Telescope consists of four 8.2-metre Unit Telescopes (UTs) and four 1.8-metre movable Auxiliary Telescopes (ATs), three of them visible in the picture. While the UTs can observe either individually either in a combined interferometric mode, the ATs are entirely dedicated to interferometry. By using this technique, astronomers can see details up to 25 times finer than with the individual telescopes. The configuration of the ATs can be changed across the platform by moving them to 30 different observing positions. This view of the VLT platform was taken toward the east where the dark-bluish shadow projected by the Earth on the atmosphere is clearly visible on the exceptionally clear horizon.