Stokes maps observed by the Hinode SOT/SP in the main sunspot of the NOAA AR 10930 on December 08, 2006. Panel a: continuum intensity I_c normalized to the mean continuum value in the quiet sun, I_QS. Panels b, c, and d: maps of the Stokes parameters Q, U, and V, respectively, normalized to local I_c. The Stokes Q, U and V maps were constructed at −0.1 Å from the 6302.5 Å line core (the selected wavelength is indicated by vertical green lines in Fig. 2). The umbra-penumbra boundary (black solid contour) was placed at I_c/I_QS = 0.26 and the external penumbral boundary (black dashed contour) is at I_c/I_QS = 0.94. The cyan arrows point towards the disk center. Red markers show three selected pixels, one located in the limb-side penumbra (“*”), and two located in the center-side penumbra (“x” and “+”, respectively); their corresponding Stokes profiles are shown in Figs. 2a, b, and c, respectively. The yellow cross shows a pixel close to the inner penumbral boundary where the inversions give B> 7 kG at log (τ) = 0 and whose Stokes profiles are shown in Fig. 2d.