Stokes I and V spectra along the two cuts marked in Fig. 9 (left two panels), and in a reference data set taken with POLIS (right panel). Left panel, left to right: intensity spectrum, Stokes V of the destretched, speckle-deconvolved, and MOMFBD data, respectively. The display range of V is  ± 0.5%. Middle panel: the same for the second cut. Right panel, left to right: I and V (±0.1%) from the POLIS data, V plus 0.2% rms noise with a display threshold of  ±0.5%. The white markers at the right border of Stokes V denote V_max > 2.5σ, the red markers V_max above the finally chosen significance level.