Test-bin composite spectrum de-reddened according to different extinction curves reported in the inset and assuming E(B − V) = 0.1 and R_V = 3.1. The slopes produced from the spectral fits according to the different extinction curves are represented in the inset. The spectrum and the slope of the continuum before the de-reddening (α_{λ,  obs}) are reported in magenta as references. The slope derived assuming the extinction curve from Gordon et al. (2016) is the closest to the average (black line).