On 1 December 2015, l’Observatoire de Paris hosted the inauguration of the Gamma-ray Cherenkov Telescope (GCT) prototype. The GCT will detect very high-energy gamma rays for the world’s largest gamma ray observatory, the Cherenkov Telescope Array (CTA).
The event was held at the Observatory’s Meudon site with speeches and presentations by representatives from l’Observatoire de Paris, Centre National de la Recherche Scientifique (CNRS), Science and Technology Facilities Council (STFC), Region Ile-de-France, the CTA and GCT consortia. Following the presentation, attendees were given a tour of the telescope and its camera, which captured CTA’s first Cherenkov light during testing just days before the event. The telescope is one of the very first to use the Schwarzschild-Couder dual-mirror optical design, which has recently been recognized as well-suited to ground-based gamma-ray astronomy, providing good image quality over a large field of view and allowing the construction of telescopes and cameras that are more compact than the single-mirror systems that are currently in use.
The GCT is one of CTA’s small size telescopes (SSTs) and will cover the high end of the CTA energy range, between about 1 and 300 TeV (tera-electronvolts). Around 70 SSTs are needed to make sure CTA is sufficiently sensitive at these enormous energies. The GCT is one of three different SST implementations being prototyped and tested around the world. Current expectations are that the array will include approximately 35 GCTs. They will be built by an international collaboration with contributions from institutes and universities in Australia, France, Germany, Japan, the Netherlands and the United Kingdom.