Performance and first measurements of the MAGIC stellar intensity interferometer
S. Abe, J. Abhir, V. A. Acciari, Arnau Aguasca-Cabot, I. Agudo, T. Aniello, Stefano Ansoldi, L. A. Antonelli, A. Arbet Engels, Cornelia Arcaro, Manuel Artero, Katsuaki Asano, A. Babić, Andrés Baquero, U. Barres de Almeida, J. A. Barrio, Ivana Batković, A. Bautista, J. Baxter, J. Becerra González, E. Bernardini, M. Bernardos, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G Bonnoli, Ž. Bošnjak, Irene Burelli, G. Busetto, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, G. Ceribella, Yating Chai, A. Cifuentes, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, Giacomo D’Amico, V. D’Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, Raniere de Menezes, Antonino Del Popolo, M. Delfino, J. Delgado, C. Delgado Mendez, F. Di Pierro, L. Di Venere, D. Dominis Prester, Alice Donini, D. Dorner, M. Doro, D. Elsäesser, Gabriel Emery, Juan Escudero, L. Fari na, Alicia Fattorini, L. Foffano, L. Font, Stefan Fröse, Satoshi Fukami, Y. Fukazawa, R. J. Garcı́a López, M. Garczarczyk, Sargis Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, Paweł Gliwny, T. Gradetzke, R. Grau, D. Green, Jarred Gershon Green, Patrick Günther, D. Hadasch, A. Hahn, T. Hassan, Lea Heckmann, J. Herrera, Dario Hrupec, Moritz Hütten, Ryo Imazawa, Kazuma Ishio, Irene Jiménez Martínez, Jenni Jormanainen, T. Kayanoki, D. Kerszberg, Gert Werner Kluge, Yukiho Kobayashi, Pouya M. Kouch, H. Kubo
Abstract
ABSTRACT In recent years, a new generation of optical intensity interferometers has emerged, leveraging the existing infrastructure of Imaging Atmospheric Cherenkov Telescopes (IACTs). The MAGIC telescopes host the MAGIC-SII system (Stellar Intensity Interferometer), implemented to investigate the feasibility and potential of this technique on IACTs. After the first successful measurements in 2019, the system was upgraded and now features a real-time, dead-time-free, 4-channel, GPU-based correlator. These hardware modifications allow seamless transitions between MAGIC’s standard very-high-energy gamma-ray observations and optical interferometry measurements within seconds. We establish the feasibility and potential of employing IACTs as competitive optical Intensity Interferometers with minimal hardware adjustments. The measurement of a total of 22 stellar diameters are reported, 9 corresponding to reference stars with previous comparable measurements, and 13 with no prior measurements. A prospective implementation involving telescopes from the forthcoming Cherenkov Telescope Array Observatory’s Northern hemisphere array, such as the first prototype of its Large-Sized Telescopes, LST-1, is technically viable. This integration would significantly enhance the sensitivity of the current system and broaden the UV-plane coverage. This advancement would enable the system to achieve competitive sensitivity with the current generation of long-baseline optical interferometers over blue wavelengths.