Improved methods for the determination of the Energy Spectrum of UHECRs with the Fluorescence and Surface Detector of the Pierre Auger Observatory

The energy spectrum of ultrahigh-energy cosmic rays (UHECRs) provides information about the extragalactic origin and propagation of cosmic rays. A combination of surface and fluorescence detector measurements of the Pierre Auger Observatory delivers a high-resolution hybrid energy spectrum. The long-term observations of the Pierre Auger Observatory allow us to re-evaluate environmental influences on detection capabilities and selection criteria using measured rather than simulated data.
In this contribution, we will demonstrate improved methods to determine the hybrid energy spectrum of UHECRs and present preliminary results.