TBS and template correction. Left: θ and z-integrated template correction α(E) from data on the sources analysed in this work. Right: effective template correction β_eff (circles) and α(E) (squares) for the sources Centaurus A  (red) and Vela X  (black). The black solid line represents the integrated value α_std of Vela X  whereas the red dashed line represents the overall template correction from the Centaurus A  data set. See text for further information.