Left: TS map (in counts) of the PWN HESS J1825-137 in the energy range 1 GeV–1 TeV with Fermi-LAT, with the region used to extract the radial profile (as used by H.E.S.S.) overlaid in white. The preferred emission direction (“major axis”) as found by H.E.S.S., along which the extent is evaluated, is indicated by the black dashed line. The position of the pulsar (black) and best-fit Fermi-LAT centre of a 2D Gaussian (magenta) are also indicated. Right: radial profile of the excess counts fit with Eq. (3) beyond the peak emission. The characteristic R(1/e) size of the nebula is indicated by a white (black) dashed line in the left (right) hand plot.