Energy spectrum of PKS 2155−304 obtained from the H.E.S.S. II mono analysis (blue) of the 2013 data corrected for EBL absorption in comparison with the contemporaneous Fermi-LAT data with a minimal energy of 0.1 GeV (red). The black line is the best-fit log-parabola model to the points and the cyan butterfly indicates the 1σ region using only the statistical errors in the combined data set analysis. The right-hand y-axis shows the equivalent isotropic luminosity (not beaming corrected).