Evolution of the observed continuum polarization of SN 2012aw, corrected for interstellar polarization (filled symbols; averaged value over the observed range 6900–7200 Å) and its V -band magnitude (open circles; values shown on right axis, from Bose et al. 2013), along with model predictions (closed diamonds for polarization, open diamonds for photometry); the model photometry accounts for extinction and distance dilution as in Hillier & Dessart (2019). The symbols at 160 d are for the model only since the last observation is at 120 d. In this hybrid 2D axisymmetric ejecta model, the ratio of polar and equatorial photospheric radii evolves from 1.02, to 1.08, 1.22, 1.36, 1.59, 1.52 and 1.26 as the SN ages from 16.1, to 46.0, 63.0, 71.9, 91.9, 107.9, and 120.0 d. As discussed in Sect. 4.2, a systematic uncertainty of ~ 0.2% exists on all continuum polarization measurements of SN 2012aw displayed in this plot, due to the uncertainty in the ISP.