Analysis of the polarization vectors’ orientation (χ_pol) as a function of the maser cloudlet position (see Sect. 3). a) Plot of the difference (and uncertainty) between the orientations of the velocity (χ_vel) and polarization (χ_pol) vectors as a function of the sky position angle (PA) of each cloudlet (defined in Sect. 3). Cloudlets with PA in the range 90°–270° have been folded in the range −90° < PA < 90°. The gray area indicates the boundary of the weighted standard deviation (± 1 σ) for the χ_pol–χ_vel values. b) Plot of as a function of the projected distance along the equatorial plane of the HMC (−32°). gives the values of χ_pol as measured counterclockwise starting from a sky position angle of −32°. In this panel, only points with offsets less than 400 AU from the equatorial plane have been plotted. For each value, the polarization fraction is quantified according to the wedge on the righthand side. The uncertainty of the measurements is of the same order as the marker size. The different regions identified in Sect. 3 are also indicated. c) Similar to panel b) with projected distances along the outflow axis (58°). Data points plotted in panel b) are not drawn.