Abstract
The Large Synoptic Survey Telescope (LSST) is an 8.4 m telescope which will be dedicated to conduct an all-sky survey in several wavelength bands. In 2006, the El Peñon summit on the Cerro Pachon mountain ridge was selected to become the site hosting the LSST telescope. Since 2003 meteorological data have been collected on Peñon and since 2006 seeing measurements have also been obtained. Also, in late 2009 a campaign was started to compare the LSST DIMM monitor to the one used by the Thirty Meter Telescope (TMT) site testing project. Here we report on the overall results on meteorological conditions at Peñon, and in particular on the optical turbulence conditions. From the LSST-TMT seeing monitor comparison it will be shown that -again- the site monitoring telescope is impacting on the measured overall seeing. The Peñon results are also compared with measurements from Cerro Tololo and Cerro Pachón. It was found that high altitude turbulence does on average not greatly vary between those sites.