ELT site testing — Cerro Armazones by night

The Extremely Large Telescope (ELT) programme office has studied half a dozen potential sites for the future ELT observatory, which, with its 40-metre-class diameter, will be the world’s biggest eye on the sky. Various aspects need to be considered in the site selection process. Parameters taken into account are not restricted to ‘sky quality’, but include more general scientific aspects, as well as parameters essential for construction and operations (e.g. accessibility, water and power supply, political stability etc.).

The above picture shows a night impression of Cerro Armazones, a site located in Chile, not very far from the ESO Paranal Observatory, home to the flagship Very Large Telescope. On the ELT Site Selection Advisory Committee's final short list for the recommended site, Armazones is also the committee’s preferred site, because it has the best balance of sky quality across all aspects and can be operated in an integrated fashion with the existing Paranal Observatory.