γ-ray SED of AP Librae from Fermi-LAT  (blue circles) and H.E.S.S. (orange squares and butterfly power-law fit). For the quiescent state, the Fermi-LAT  best-fit power-law (blue butterfly) has been extrapolated toward the H.E.S.S. energy range taking EBL absorption into account (dash-dotted line). The Fermi-LAT  log-parabola fit is shown in gray, and its extrapolation taking the EBL absorption into account is shown in light gray. The flare SED as measured by Fermi-LAT  is given by the red butterfly and open squares. The shorter and longer errors bars indicate statistical-only and the quadratic sum of statistical and systematic uncertainties, respectively (see text).