E-ELT site characterization status

The site characterization for the future European Large Telescope (E-ELT) is a key issue within the European proposal funded by the EC, within the "ELT Design Study" proposal. The organization, working scheme and baseline frameworks are reviewed. For the definition of the working package WP12000 "Site Characterization" important use has been done of previous works in the definition of techniques and tools for the study of the atmosphere above observing sites. We have also taken advantage of the number of data already available which have naturally defined a ranking among the known places which have also been taken as a base line for preselecting the candidate sites. The work will last 4 years, started in 2005 and is organized in subtasks whose main objectives are the following: WP12100: To characterize two top astronomical sites (ORM and North-Paranal) and to explore 3 other alternatives (Macon in Argentina, Izana in Spain and Aklim in Morocco) suitable to install an ELT under the best conditions (Dome C is been currently under investigation, and no particular effort will be put in this site, but rather its atmospheric properties will be compared to the above mentioned sites). WP12200 is dedicated to design, build and operate a standard equipment in all the sites and to perform long term campaign. WP12300 will investigate wavefront properties over large baselines (50-100 m) corresponding to the size of the future ELT, as well as the fine characterization of the optical turbulence within the boundary layer. A similar plan is being carried out by the TMT site selection team. For the sake of saving resources (budget and people), the TMT preselected sites (all in America) are not included in our European study.