The HiRes Stereo Measurement of the UHECR Spectrum

The High Resolution Fly's Eye (HiRes) Experiment has measured the ultra-high energy cosmic ray (UHECR) energy spectrum using a stereo technique combining the observations of its two sites to provide very accurate determination of extensive air shower geometry. The spectrum will be shown, along with previous measurements in monocular mode, fits to all the spectra to show the energy of the observed GZK suppression and a discussion of systematic errors.