Discovery of very high energy gamma-rays from Markarian 180 triggered by an optical outburst

© The American Astronomical Society. We would like to thank the IAC for the excellent working conditions at the ORM in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Spanish CICYT, ETH research grant TH 34/04 3, and the Polish MNiI grant 1P03D01028 is gratefully acknowledged. We also thank H. D. and M. F. Aller, at the University of Michigan Radio Observatory, for providing us with the UMRAO data.
The high-frequency-peaked BL Lacertae object Markarian 180 (Mrk 180) was observed to have an optical outburst in 2006 March, triggering a Target of Opportunity observation with the MAGIC telescope. The source was observed for 12.4 hr, and very high energy gamma-ray emission was detected with a significance of 5.5 sigma. An integral flux above 200 GeV of (2.3 +/- 0.7) x 10(-11) cm(-2) s(-1) was measured, corresponding to 11% of the Crab Nebula flux. A rather soft spectrum with a photon index of has been determined. No significant flux -3.3 x 0.7 variation was found.
German BMBF
German MPG
Italian INFN
Spanish CICYT
ETH
Polish MNiI
Depto. de Estructura de la Materia, Física Térmica y Electrónica
Fac. de Ciencias Físicas
TRUE
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