ELT SITE TESTING

Starting with a Memorandum of Understanding (MOU) with the California Extremely Large Telescope (CELT) group in FY 2002, AURA has played a major collaborative role in evaluating candidate sites for TMT. These sites would also be suitable for other telescopes with similar requirements. The list of candidate sites has been narrowed by investigations of logistical issues such as land ownership, as well as by a series of remote sensing studies that have used satellite data to quantify the number of clear nights and the precipitable water vapor for each site. Each prime candidate site has also been modeled using computa-tional fluid dynamics to investigate the boundary layer turbulence over the site under various wind speeds and directions.

In-situ site testing equipment has been developed, and multiple copies have been purchased and assembled. This equipment includes weather stations, differential image motion monitors (DIMMs) capable of recording integrated seeing through the upper atmosphere and ground-layer, and multi-aperture scintillation sensors (MASS) capable of mapping turbulence profiles above candidate sites. Weather stations, DIMM and MASS units have been deployed on several candidate sites.

Site selection is expected to be complete no later than the middle of 2008. The role of the site testing group in support of subsequent characterization of the TMT site — or other ELT sites — has yet to be defined.

NOAO Sites Group