Left: HESS J1303−631 fitted Gaussian mean, c(E), measured from the pulsar position, as a function of energy. Right: the PSF corrected intrinsic Gaussian extension (w_int(E), blue) is overlaid with the fitted uncorrected excess Gaussian extension (w_img(E), black dashed) as a function of energy. The points are placed at the average energy of the photons falling in the corresponding energy bin (indicated by the horizontal error bars, not used in fit).