Left: comparison between the model 2D-X1-SCL0p5 and observations of SN 2012aw for epoch 1 (i.e., 16.1 d after explosion) using a density scaling with A of 0.5 (left) or 4.0 (right). All inclinations between polar and equatorial directions are shown. For SN 2012aw, we correct for the instrumental polarization, for the interstellar polarization and redshift (as well as reddening for F_I). The observed normalized Stokes parameters have been rotated by 28 deg (see Sect. 4.3). The ordinate range is the same for q_rot and u_rot. A binning of 25 Å is used for q_rot, u_rot, and P, while a binning of 5 Å is used for F_I. As describedin the caption to Fig. 5, a representative 1σ uncertainty in the polarization was calculated, and is shown in the bottom panels. The polarization displayed in the bottom panels for the SN 2012aw data is the “traditional polarization”, as defined in the caption to Fig. 5. For all models u_rot is null across the spectrum, and so is not plotted.