RT Journal Article T1 The central pixel of the MAGIC telescope for optical observations A1 Antoranz Canales, Pedro A1 Barrio Uña, Juan Abel A1 Contreras González, José Luis A1 Fonseca González, María Victoria A1 López Moya, Marcos A1 Miranda Pantoja, José Miguel A1 Nieto Castaño, Daniel AB The MAGIC telescope has been designed for the observation of Cherenkov light generated in Extensive Air Showers initiated by cosmic particles. However, its 17m diameter mirror and optical design makes the telescope suitable for direct optical observations as well. In this paper, we report about the development of a system based on the use of a dedicated photo-multiplier (PMT) for optical observations. This PMT is installed in the centre of the MAGIC camera (the so-called central pixel). An electro-to-optical system has been developed in order to transmit the PMT output signal by an optical fibre to the counting room, where it is digitized and stored for off-line analysis. The performance of the system using the optical pulsation of the Crab nebula as calibration source is presented. The time required for a 5 sigma detection of the Crab pulsar in the optical band is less than 20s. The central pixel will be mainly used to perform simultaneous observations of the Crab pulsar both in the optical and gamma-ray regimes. It will also allow for periodic testing of the precision of the MAGIC timing system using the Crab rotational optical pulses as a very precise timing reference. (c) 2008 Elsevier B.V. All rights reserved. PB Elsevier Science BV SN 0168-9002 YR 2008 FD 2008-05-15 LK https://hdl.handle.net/20.500.14352/50836 UL https://hdl.handle.net/20.500.14352/50836 LA eng NO © Elsevier. The authors wish to thank the financial support given by the CICYT (project FPA2003-9543-C02-01) which made this work possible, and the IAC for providing excellent working conditions in La Palma. The MAGIC telescope is mainly supported by BMBF (Germany), CICYT (Spain), INFN and MUR (Italy). We also acknowledge Razmik Mirzoyan, Manel Martinez, Eva Domingo and the IFAE engineering team, Alex Gonzalez and Isaac Martinez for their valuable help in the installation. Also, we thank Juan Cortina and Emma On˜ a-Wilhelmi of the IFAE group for their suggestions and help in modifying the PMT base. NO CICYT NO German BMBF NO INFN NO MUR DS Docta Complutense RD 10 abr 2025