Recent Observations of gamma-rays above 1.5 TeV from Mkn 501 with the HEGRA 5 m2 Air Cherenkov Telescope
D. Kranich, T. Deckers, E. Lorenz, D. Petry, G. Rauterberg, the HEGRA Collaboration
Abstract
Since February 1997 the BL Lac object Mkn 501 is in a ``high state'' of gamma-ray emission. The HEGRA collaboration has studied Mkn 501 with their air Cherenkov telescopes on La Palma. Here we report on observations with the 5 m2 telescope (threshold approx. 1.5 TeV) operated in a stand alone mode. We observed a rapidly varying flux between 0.5 to 6 times of that from the Crab Nebula. On average an integral flux above 1.5 TeV of (2 + 1.3 - 0.5) x 10-11 cm-2 s-1 has been determined. The spectrum extends at least up to 10 TeV with an integral power law coefficient of 1.8 +- 0.2 and seems to be steeper than in 1996.
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