Intensity interferometry with MAGIC

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.