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Astron. Astrophys. 320, L5-L8 (1997)

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6. Conclusion

We have detected [FORMULA] -radiation above 1.5 TeV from Mkn 501 using the first imaging air Cherenkov telescope of the HEGRA Collaboration. An integral flux above 1.5 TeV of approx. [FORMULA] cm-2 s-1 was found from the March - August 1996 data. Mkn 501 shows a spectrum compatible with a differential spectral index of 2.6 [FORMULA], where the large error is mainly statistical.

Our near contemporary Crab Nebula data show an excess rate 3.4 times larger than that for Mkn 501 and a spectral index of 2.6 [FORMULA], from which a flux above 1.5 TeV of approx. [FORMULA] cm-2 s-1 is calculated. This is in very good agreement with our earlier measurement using CT2 at a threshold of 1 TeV (Petry et al. 1996 ). Within the statistical errors, the integral flux above 1.5 TeV from Mkn 501 is less than that from the Crab Nebula by a factor of 2.9 [FORMULA].

In 70 nights of data no significant deviation of the Mkn 501 event rate from a mean of 2.4 events h-1 was observed.

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© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998
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