Measuring Gamma-Ray Energy Spectra with the HEGRA IACT System

The stereoscopic reconstruction of air showers viewed by multiple imaging atmospheric Cherenkov telescopes (IACTs) allows a more precise reconstruction of shower energies and hence an improved determination of energy spectra. Reconstruction techniques and in particular new systematic checks are discussed on the basis of the large sample of gamma-rays from Mkn 501 detected with the HEGRA IACT system. (Talk presented at the Workshop ``Towards a Major Atmospheric Cherenkov Detector V'', Kruger Park, South Africa, 1997