FACT - Status and experience from three years operation of the first SiPM camera

Abstract

The First G-APD Cherenkov Telescope (FACT) is pioneering the usage of solid state photosensors (G-APD, also known as SiPM). The 1440 pixel camera is installed in a 9.5 m2 refurbished HEGRA telescope on the Canary Island La Palma. Physics data-taking with FACT started in October 2011, a few hours after installation of the camera. Since Summer 2012, FACT is operated remotely without the need of a data-taking crew on site. During more than three years of operation of FACT, G-APDs have proven to be very reliable. Despite operating them regularly also under very strong moonlight conditions, the GAPDs show no change in their properties or any indication for aging. This allows FACT to have a successful monitoring program of the brightest TeV blazars in the Northern hemisphere and several flare-alerts have been sent to the community. This proceeding summarizes the history and status of FACT as well as reporting the lessons learned about the usage of SiPM in a Cherenkov telescope from the construction and operation of FACT.