Inauguration and First Light of the GCT-M Prototype for the Cherenkov Telescope Array

TL;DR

The paper reports the successful inauguration and first light observation of the GCT-M prototype camera for the Cherenkov Telescope Array, demonstrating its capability to detect Cherenkov light for gamma-ray astronomy.

Contribution

This work presents the first operational deployment of the GCT-M prototype, showcasing its innovative dual-mirror design and advanced digitising camera system for CTA.

Findings

First Cherenkov light detected by GCT-M prototype

Successful integration of the GCT-M camera at observatory

Demonstrated capability for high-energy gamma-ray detection

Abstract

The Gamma-ray Cherenkov Telescope (GCT) is a candidate for the Small Size Telescopes (SSTs) of the Cherenkov Telescope Array (CTA). Its purpose is to extend the sensitivity of CTA to gamma-ray energies reaching 300 TeV. Its dual-mirror optical design and curved focal plane enables the use of a compact camera of 0.4 m diameter, while achieving a field of view of above 8 degrees. Through the use of the digitising TARGET ASICs, the Cherenkov flash is sampled once per nanosecond continuously and then digitised when triggering conditions are met within the analogue outputs of the photosensors. Entire waveforms (typically covering 96 ns) for all 2048 pixels are then stored for analysis, allowing for a broad spectrum of investigations to be performed on the data. Two prototypes of the GCT camera are under development, with differing photosensors: Multi-Anode Photomultipliers (MAPMs) and Silicon Photomultipliers (SiPMs). During November 2015, the GCT MAPM (GCT-M) prototype camera was integrated onto the GCT structure at the Observatoire de Paris-Meudon, where it observed the first Cherenkov light detected by a prototype instrument for CTA.