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The giant radio galaxy M87, well studied from radio to X-ray energies, is located in the Virgo cluster of galaxies at a distance of ~16 Mpc (redshift z=0.00436). M87 has been observed with the HEGRA stereoscopic system of five Cherenkov telescopes in the years 1998 and 1999 for more than 80 h. An excess of TeV γ-rays on the 4σ level has been found in the data corresponding to an integral flux (E>730...
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