We thank the Instituto de Astrofisica de Canarias (IAC) and the ORM observatory for support and excellent working conditions. We are grateful to the authors of CORSIKA and to the KASCADE collaboration for many stimulating discussions. The experiment HEGRA is supported by the German BMBF and DFG and the Spanish CICYT.
© European Southern Observatory (ESO) 2000
Online publication: July 7, 2000