The main goals of the upgrade are a reduction in the energy threshold of the telescope, improved sensitivity, and better stability of operation. The new camera is based on the FlashCam design, which has been developed for the use in the Cherenkov Telescope Array (CTA) by a consortium of the universities from Zürich, Tübingen, Erlangen and Innsbruck under the lead of the Max Planck Institute for Nuclear Physics in Heidelberg. After extensive tests of a complete prototype with its hardware, firmware and software, the camera was shipped to Namibia, where it arrived at the beginning of October 2019. After adaption of the mechanical telescope interfaces, the camera was installed on October 20th (Fig. 1).
The telescope was ready to make astrophysical observations just two days after mechanical installation. In its first night of operation, the telescope was pointed at the Crab Nebula, among other targets. Fig. 2 shows the gamma-ray sky map around the Crab Nebula obtained with the standard H.E.S.S. real-time analysis during these first observations with the upgraded telescope. A clear detection is visible at the position of the Crab Nebula.
In the meantime, the telescope with its new camera is participating in routine observations with the complete H.E.S.S. array, confirming the expected performance improvements and stability of operation. With its high-quantum-efficiency light sensors and sophisticated trigger and readout scheme, the new camera will further boost the performance of H.E.S.S.’s world’s largest Cherenkov telescope. With this success the H.E.S.S. collaboration, together with the FlashCam consortium, have also demonstrated a highly efficient mode for the installation and commissioning of cameras, as will be required for the deployment of the around 100 telescopes of the Cherenkov Telescope Array (CTA).