F. Aharonian et al | Searcharxiv

arXiv1998

Measurement of the radial distribution of Cherenkov light generated by TeV gamma-ray air showers

Using air showers induced by TeV gamma-rays from Mrk 501, the radial distribution of Cherenkov light is investigated. The shower geometry is reconstructed from the stereoscopic shower images obtained with the telescopes of the HEGRA IACT system. We observe a change in the shape of the light pool with shower energy, and with zenith angle. Data are well reproduced by Monte-Carlo air shower simulations.

astro-ph↗

arXiv1997

Measurement of the flux, spectrum, and variability of TeV gamma-rays from Mkn 501 during a state of high activity

Between March 16, 1997 and April 14, 1997, a high flux level of TeV gamma-rays was observed from Mkn 501, using the HEGRA stereoscopic system of four imaging Cherenkov telescopes. The flux level varied during this period from about one half up to six times the flux observed from the Crab Nebula. Changes of the detection rate by a factor of up to 4 within 1 day have been observed. The measured differential energy spectrum of the radiation follows a power law from 1 TeV to 10 TeV. The differential spectral index of 2.47{+-}0.07{+-}0.25 is close to that of the Crab Nebula of 2.66{+-}0.12{+-}0.25.

astro-ph↗