RT Journal Article T1 Variable very-high-energy gamma-ray emission from the microquasar LS I +61 303 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 AB Microquasars are binary star systems with relativistic radio-emitting jets. They are potential sources of cosmic rays and can be used to elucidate the physics of relativistic jets. We report the detection of variable gamma-ray emission above 100 gigaelectron volts from the microquasar LSI+61 303. Six orbital cycles were recorded. Several detections occur at a similar orbital phase, which suggests that the emission is periodic. The strongest gamma-ray emission is not observed when the two stars are closest to one another, implying a strong orbital modulation of the emission or absorption processes. PB Amer Assoc Advancement Science SN 0036-8075 YR 2006 FD 2006-06-23 LK https://hdl.handle.net/20.500.14352/50930 UL https://hdl.handle.net/20.500.14352/50930 LA eng NO © American Association for the Advancement of Science.We thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatory Roque de los Muchachos in La Palma. Supported by the Bundesministerium für Bildung und Forschung and Max-Planck-Gesellschaft (Germany), INFN (Italy), Comisión Interministerial de Ciencia y Tecnología and Ministerio de© American Association for the Advancement of Science. Educación y Ciencia grant AYA2004-07171-C02-01 (Spain), ETH (Switzerland) research grant TH-34/04-3, and Ministerstwo Nauki i Informatyzacji (Poland) grant 1P03D01028. NO Bundesministerium für Bildung und Forschung and Max-Planck-Gesellschaft (Germany) NO INFN (Italy NO Comisión Interministerial de Ciencia y Tecnología y Ministerio de Educación y Ciencia (Spain) NO ETH (Switzerland) NO Ministerstwo Nauki i Informatyzacji (Poland) DS Docta Complutense RD 29 jun 2025