An Auxiliary Telescope opens up

This video shows an Auxiliary Telescope (AT) at ESO's VLT as its dome opens up.

The ATs are very unusual telescopes, as they are self-contained in their ultra-compact protective domes, and travel with their own electronics, ventilation, hydraulics and cooling systems. Each AT has a transporter that lifts the telescope and moves it from one position to the other.

The ATs allow the VLT to operate as an interferometer every night. They are mounted on tracks and can be moved between precisely defined observing positions from where the beams of collected light are combined.