The Cherenkov Telescope Array1 (CTA) is the next-generation ground-based observatory for very-high-energy gamma rays. The CTA consists of three types of telescopes with different mirror areas to cover a wide energy range (20 GeV–300 TeV) with an order of magnitude higher sensitivity than the predecessors. Among those telescopes, the Large-Sized Telescope (LST) is designed to detect low-energy gamma rays between 20 GeV and a few TeV with a 23 m diameter mirror. To make the most of such a large light collection area (about 400 m2), the focal plane camera must detect as much reflected Cherenkov light as possible. We have developed each camera component to meet the CTA performance requirements for more than ten years and performed quality-control tests before installing the camera to the telescope.2, 3 The first LST (LST-1) was inaugurated in October 2018 in La Palma, Spain (Figure 1).4 After the inauguration, various calibration tests were performed to adjust hardware parameters and verify the camera performance. In parallel, we have been developing the analysis software to extract physical parameters from low-level data, taking into account some intrinsic characteristics of the switched capacitor arrays, Domino Ring Sampler version 4 (DRS4), used for sampling the waveform of a Cherenkov signal. In this contribution, we describe the hard- ware design of the LST camera in Section 2, a procedure for low-level calibration in Section 3, and the readout e of the LST camera after the hardware calibration with a dedicated analysis chain in Section 4.
MAGIC is a system of two 17m diameter Imaging Atmospheric Cherenkov Telescopes (IACTs) situated on the observatory of the Roque de los Muchachos on the island of La Palma, 2200m asl. MAGIC is currently in operation for the observation of VHE gamma-ray sources. Here we report the installation of a system to perform intensity interferometry observations with these telescopes. We investigated the feasibility of this technique for these telescopes to be used for high resolution observation of stellar objects. The optics and electronics of MAGIC are designed for single photoelectron resolution and a sub-nano second timing precision and they are ideally suited for optical interferometry observations. During easter 2019 we have installed a simple setup using the central PMT pixels in the camera to test the working principle that MAGIC can be used for intensity interferometry observations. We demonstrate MAGIC is able to reach resolutions of about 0.7 mas with a baseline of 85m between the telescopes. Thanks to the large mirror area of MAGIC of about 239 m 2 we achieve a sensitivity of roughly 10 times better than that achieved in the 1970's with the Narrabri interferometer. Currently, a professional readout with GPU realtime analysis has been developed that will be used in the near future for observations.
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