E-ELT SITE

Towards a site for the E-ELT

The E-ELT programme office is currently studying a number of potential sites for the E-ELT observatory. A decision on the site is foreseen by the end of 2009. After down-selecting sites during the last couple of years, only a handful of locations are still being considered. These include sites located near the existing ESO facilities La Silla and Paranal, a site in Argentina at a similar latitude as Paranal, as well as a site on La Palma close to the Roque de los Muchachos observatory.

site testing Vernin

The site selection process

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. For example, aspects that the project is currently looking at include:

  • Atmospheric parameters: number of clear nights, infrared properties (height, temperature, precipitable water vapour, etc), seeing, atmospheric turbulence profile, mean coherence length and time, outer scale length, etc.
  • Scientific synergy aspects: which facilities will (be) support(ed by) the E-ELT (e.g. VLT/VLTI, ALMA, surveys such as LSST, JWST, SKA, etc) and where are they located?
  • Construction aspects: a flat surface equivalent to several football fields is needed, over 1500 containers will need to be delivered to the construction site from all over the world, construction will last several years – what is the impact on construction cost and schedule of the location?
  • Logistical aspects: for its operations, the observatory will require up to 10 MW of power – is a power grid conveniently close? Where will the water come from? Where will the ca. 150 staff live (on site and privately)?

The site selection process is supported by FP6 activities described in an SPIE paper.
A Site Selection Advisory Committee (SSAC) has been formed and is advising the ESO Director General who will deliver a proposal to the ESO council.

Impressions of some of the sites under study

From left to right: Roque de los Muchachos (Canary Islands), Ventarrones (Chile), Aklim (Morocco), and Macon (Argentina).