Determining the extinction due to ice and silicate absorption. Top: Observed MIRI-MRS spectrum of IRAS2A (blue) with the global continuum estimate (red) overplotted. The continuum is based on a third-order polynomial fit to emission- and absorption-free wavelength ranges. The positions of the H₂ v = 0 rotational transitions are indicated with the vertical dashed gray lines. Bottom: Differential extinction in units of optical depth (blue) of the absorption features as a function of wavelength derived from the global continuum estimate (Eq. (C.2)). Overplotted is the absolute extinction (orange) computed using Eq. (C.3); see the main text for more details. The total extinction (green) is computed from the sum of the two (Eq. (C.1)).