χ² values for different subsets of hydrodynamical LC models compared to the observed LCs. Top panel:χ² values for the different LC models compared to observations, over a range of 10–17.5 M_⊙ (ΔM = 2.5 M_⊙) and an explosion energy of 0.4–1.2 × 10⁵¹ erg (ΔE = 0.4 × 10⁵¹). Bottom panel:χ² values for the different LC models compared to observations, over a range of 9–15 M_⊙ (ΔM = 0.5 M_⊙) and an explosion energy of 0.6 to 1.0 × 10⁵¹ ergs (ΔE = 0.1 × 10⁵¹), with an “X” demarcating the best-fit model.