33ND INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE The effect of the fluorescence yield selection on the relative energy scales of the

The Auger and TA experiments use different fluorescence yields for shower reconstruction. The corresponding effect on their relative energy scales is studied. Simple analytical calculations show that the energy reconstructed by the TA telescopes should be larger than that of Auger. A detailed simulation has provided a more realistic evaluation of this effect showing similar results. Our analysis indicates that, if we neglect other contributions, the discrepancy in the energy scales due to the fluorescence yield would be of about 17%