Left panel: normalized early rest-frame BVi-band (top to bottom) light curves of KSN-2017iw up to  ∼40% of B-band peak flux compared to the best-fit power-law model (dashed curves; Equation (D1)) with ﹩{\chi }_{{\rm{R}}}^{2}﹩ = 2.2 (Appendix D). The vertical and horizontal dotted lines represent t_PL of the fit (= “first light”) and zero flux, respectively. Right panel: fit residuals divided by the photometric error bars. The horizontal dashed line represents zero residual, while the dotted ones represent the 1σ region of the residual data points.