Spatial variations along the slit of the Stokes parameters. Panel a: spatial variation of the Hα Stokes profiles shown in Fig. 7. We applied a binning of 6 and 10 pixels along the spatial and spectral dimensions, respectively. Each profile, after the spatial binning, covers 8.4″ on the slit. The selected region starts at 110.6″ and ends at 161″ (see the thin black lines in Fig. 7). The ID of the observation used is 40. Panel b: spectropolarimetric images. The color scale saturates in black at ±0.2% for Q/I, and U/I and ±0.1% for V/I. The thin black lines show the spatial region used in Fig. 7a. The observation was taken at the heliospheric east limb at μ = 0.1. The observation ID is 40.