HST/FOC polarization maps of Mrk 3 through filter F502M. Left: Intensity map overlaid with the integration regions used in Table 2. Right: Debiased polarization degree. Darker pixels have [S/N]_P < 1. Both maps are at spatial binning of 0.10″, smoothed using a 0.15″ FWHM Gaussian kernel. 30 pixels have [S/N]_P ≥ 3. The orange cross displays the estimated location for the obscured nucleus (Kishimoto et al. 2002).