Interpolation of the Ap Lib SED by two-third degree polynomial functions, showing the synchrotron component (red) and the inverse-Compton component (blue). Black data: Simultaneous and quasi-simultaneous data, dots: Planck, Squares: WISE, stars: Swift-UVOT, diamonds: Swift-XRT, crosses: Fermi-LAT, grey dots: Archive data for informational purposes only, grey bow-tie:HESS. The red rectangle is the uncertainty area of the Compton peak position. Only quasi-simultaneous and HESS data are used for the interpolation.