Upper panel: Chandra ACIS close-up view of the SN 1006 southwestern limb in the 0.5−7 keV band. The regions selected for proper-motion measurements are shown in white. Central panel: azimuthal variation of the proper motion (normalized to its maximum value) in the southwestern limb of SN 1006 measured with Chandra (black crosses) and predicted by models RUN2_G (red crosses). Lower panel: same as central panel for RUN2_UN (green crosses). The dashed crosses refer to the bulge region. Error bars indicate the 1σ confidence level for the X-ray data (black solid lines) and the sensitivity errors for the models.