2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/14326A programme of detailed simulations of the response of the Durham Mark 6 atmospheric Cherenkov telescope is in progress. The effective collecting area for triggering by gamma-ray showers after application of selection criteria is derived as a function of energy. An initial result from the larger events in the 1996 and 1997 observations of the BL Lac PKS 2155-304 is that the time averaged flux above 1.5 TeV was (6.7 +/- 2.2) x 10^-8 m^-2 s^-1.4 pages, 3 figures, to appear in the Proceedings of 26th International Cosmic Ray Conference (Salt Lake City, 1999)Astrophysicstext