2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/178384We have measured the cosmic ray spectrum above 10^17.2 eV using the two air fluorescence detectors of the High Resolution Fly's Eye observatory operating in monocular mode. We describe the detector, photo-tube and atmospheric calibrations, as well as the analysis techniques for the two detectors. We fit the spectrum to a model consisting of galactic and extra-galactic sources.4 pages, 4 figures. Uses 10pt.rtx, amsmath.sty, aps.rtx, revsymb.sty, revtex4.clsAstrophysicstext