potw1848 — Picture of the Week
Construction of the ELT Technical Facility at Paranal
26 November 2018: This photo shows the future site of the Technical Facility for ESO’s Extremely Large Telescope (ELT) — and construction is well underway! Situated at ESO’s Paranal Observatory in the Chilean Atacama Desert, this facility will be the maintenance hub for the ELT, which will take up residence on Cerro Armazones. Behind the site, ESO’s Very Large Telescope (VLT) can be seen standing high up on Cerro Paranal. The ELT’s 39-metre primary mirror will be made up of 798 hexagonal segments, and will be controlled by a system of very-high-precision sensors. This technology, known as active optics, will allow the telescope to continually adjust each individual segment to account for disturbances such as temperature, gravity and pressure due to wind, in order to maintain the perfect shape to enable optimal observations. To maintain tip-top quality, this colossal mirror must undergo a regular process of stripping, washing, and recoating. Since each individual ...