Extinction taken as the amplitude of the second dip (observed at JD = 2458585) as a function of the filter wavelength (dots). The full lines represent extinction laws at different values of R_V = A_V/E(B − V) according to Cardelli et al. (1989). The dotted black line is the model by Koutoulaki et al. (2019). The dashed line represents our two-component model (Eq. (1)). All curves are normalized to the observed extinction in the g′ band (λ_c = 4800 Å).