Antoranz Canales, PedroBarrio Uña, Juan AbelContreras González, José LuisFonseca González, María VictoriaLópez Moya, MarcosMiranda Pantoja, José MiguelNieto Castaño, Daniel2023-06-202023-06-202009-010004-636110.1051/0004-6361:20079048https://hdl.handle.net/20.500.14352/44001© ESO 2009. We would like to thank the IAC for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN and the Spanish CICYT is gratefully acknowledged. This work was also supported by ETH research grant TH-34/04-3 and by Polish grant MNiI 1P03D01028.The active galactic nucleus PG1553+113 was observed by the MAGIC telescope in July 2006 during a multiwavelength campaign, in which telescopes in the optical, X-ray, and very high energies participated. Although the MAGIC data were affected by strong atmospheric absorption (calima), they were analyzed after applying a correction. In 8.5 h, a signal was detected with a significance of 5.0 sigma. The integral flux above 150 GeV was (2.6 +/- 0.9) x 10(-7) ph s(-1) m(-2). By fitting the differential energy spectrum with a power law, a spectral index of -4.1 +/- 0.3 was obtained.engjournal articlehttp://dx.doi.org/10.1051/0004-6361:20079048http://www.aanda.orgopen access537539.1BL Lacertae ObjectsTelescopePG-1553+113SpectroscopyRedshifts.Electrónica (Física)ElectricidadFísica nuclear2202.03 Electricidad2207 Física Atómica y Nuclear