Thermodynamic variables plotted for 15 M_⊙, with and without the opacity corrections. The model is plotted during silicon shell burning some minutes before collapse. The solid line shows the model using the opacity upgrades for the radiative and conductive opacity as detailed in Sect. 3. The dotted line shows the model run with the opacity previously implemented in GENEC. We display the compactness at an entropy per baryon s = 4, computed using the definition in Eq. (24).