Combined H.E.S.S. gamma-ray spectrum of RX J1713.7−3946 generated from data of 2003, 2004, and 2005 (Data set III, Table 1). Data are corrected for the variation in optical efficiency. Error bars are  ± 1σ statistical errors. These data might be described by a power law with exponential cutoff of the form dN/dE = I₀   E ^− Γ   exp( − (E/E_c)^β). The best-fit result (black solid line) is given here for β = 0.5 (fixed), Γ = 1.8, and E_c = 3.7 TeV (cf. Table 4 for the exact values). Note that the fit function extends as dashed black line beyond the fit range for illustration. For comparison, the best fit of a power law with exponential cutoff and β = 1, obtained solely from the 2004 data (Aharonian et al. 2007), is shown as dashed red line. A model-independent upper limit, indicated by the black arrow, is determined in the energy range from 113 to 300 TeV.