Reanalysis of the high energy cutoff of the 1997 Mkn 501 TeV energy spectrum

Data taken with the HEGRA system of imaging atmospheric Cherenkov telescope s during the 1997 flares of Markarian 501 (Mkn 501) are reanalyzed using an algorithm providing improved energy resolution. A resolution of 10% to 12% is obtained by accounting for the variation of the Cherenkov light yield w ith the height of the shower maximum in the atmosphere. The improved energy resolution is particularly relevant for the study of the high-energy cutof f in the spectrum, which might be caused by interactions with the intergala ctic infrared background radiation. The reanalysis presented here confirms the results obtained in the previous analysis, but hints a steeper slope of the spectrum in the region around 20 TeV.