ROSAT/PSPC image of the vignetting-corrected and background-subtracted count rate in the 1−2.5 keV band. The image has been smoothed with a Gaussian of width σ = 5′. The white contours denote the levels of the H.E.S.S. correlated significance, as in Fig. 1. The position of the pulsar PSR J1357−6429 is marked with a green triangle. The yellow dashed circles show the source and background regions used to estimate the significance of the extended X-ray emission.