Towards f inal characteris ation and performance of the GCT prototype telescope structure for the Cherenkov Telescope Array

Abstract

The Gamma-ray Cherenkov Telescope (GCT) is an innovative dual-mirror solution proposed for the Small-Size-Telescopes of the future Cherenkov Telescope Array (CTA), capable of imaging the showers induced by cosmic gamma-rays with energies from a few TeV up to 300 TeV. The Schwarzschild-Couder design on which the telescope optical design is based makes possible the construction of a fast telescope (primary mirror diameter 4 m, focal length 2.3 m) with a plate scale well matched to compact photosensors, such as multi-anode or silicon photomultipliers (MAPMs and SiPMs, respectively) for the camera. The prototype GCT on Meudon's site of the Observatoire de Paris saw first Cherenkov light from air showers in November 2015, using an MAPM-based camera. In this contribution, we firstly report on the prototype GCT telescope's performance during its assessment phase. Secondly, we present the telescope configuration during a campaign of observations held in spring 2017. Finally, we describe studies of the telescope structure, such as the pointing and tracking performance.

Observing the sky at extremely high energies with CTA: Status of the GCT project

“…A series of settings adjustement, tests, and data taking were performed both for the telescope and the CHEC-M camera that were both operated remotely from the control room for the first time. Several thousands of cosmic showers were registered on the night sky under various conditions, at different azimuth and elevation without tracking, and while tracking two VHE sources, Mrk 421 and Mrk 501 (see Fig.5a, and references [12,15] for more details). The data analysis is now in progress, using when possible the standard CTA pipeline currently under development.…”

“…Moreover, progresses were also made in optimising the primary mirror alignment, safety and operation procedures implementation, optics characterisation, reliability, availability, maintainability and safety analysis, as well as pointing and tracking performance tests [12]. To optimise the pointing precision, an ATIK monochromatic camera was installed at the focal surface in place of the Cherenkov camera.…”

“…For more descriptive details on the tests results of the GCT structure please refer to [12]. The CHEC camera contains 2048 pixels of about 6x6 mm 2 , arranged on a curved focal surface to approximate the required radius of curvature requested by the SC optics.…”

Final characterisation and design of the Gamma-ray Cherenkov Telescope (GCT) for the Cherenkov telescope array

“…The verification of the design performances with respect to CTA requirements is ongoing. The mechanical structure has been fully validated [5,6] . The remaining work consists of consolidating the optical characterisation of the pGCT and software testing.…”