Laser guide star facility at La Silla Paranal Observatory: latest upgrades, operation, and performance

At Paranal Observatory in the YEPUN (UT4) telescope, two instruments are installed and equipped with adaptive optics systems: an infrared spectro imager (CONICA) below the adaptive optics module NAOS; and an integral field spectrograph (SINFONI). In the same telescope, the Laser Guide Star Facility (LGSF) is installed to provide a reference star to the adaptive optics systems. The LGSF is tuned to the sodium D2 line to use the resonance fluorescence of atomic sodium in the mesospheric layer at an altitude of 90 Km. The LGSF system has been fully operational for several years now. During this time, important modifications have been made to the system to increase its availability, simplify its remote operation and improve its performance. In this contribution, we report on the latest upgrades in hardware as well as the software of the system. Some upgrades like the exchange of the cooling system of the VERDI lasers, as well as the exchange of motors in the PARSEC laser system, have been critical to improve the performance of the system. We also describe the improvements in the maintenance and operation procedures and operational constraints we have faced so far. Finally, we present and analyze the latest technical performance achieved by the LGSF in operational conditions.