The largest astronomical instrument in the world, the European Extremely Large Telescope (E-ELT), will likely be built at Cerro Armazones in northern Chile, the European Southern Observatory (ESO) announced today. The move comes as little surprise because all of ESO's telescopes are currently in Chile and most expected the enormous addition to follow suit.
Delegates to ESO's council meeting yesterday at the organization's headquarters in Garching, Germany, heard a report from a site selection advisory committee that had investigated the local conditions and infrastructure at four different sites in Chile and one on the Spanish island of La Palma. Although the site selection committee said that all five sites had very good astronomical viewing conditions, Cerro Armazones stood out with the best balance of sky quality and proximity to another ESO facility, the Very Large Telescope at Cerro Paranal. The two observatories could be run in an integrated way if the E-ELT were sited there.
The E-ELT will have a primary mirror 42 meters across and will cost ESO's 15 member nations an estimated €800 million. The site selection committee spent 4 years investigating the best place for this giant project. Apart from the five short-listed locations, the committee also studied sites in Morocco, Argentina, and Tenerife, another of Spain's Canary Islands. Its investigations involved setting up viewing instruments at the sites for long periods to assess the number of days with good viewing throughout the year.
Although the conclusion of the site selection committee carries much weight, the final decision will be made by the full ESO council which next meets in June. The council will have to consider other social and political factors. Spain is campaigning hard to host the telescope, arguing that it would be better to build it on European soil. That campaign last month won the support of the President of the European Parliament, Jerzy Buzek.