Depletion and abundances simulations with the Athena-XIFU instrument for the source and the hypothetical interstellar dust composition presented in the text. Top: transmittance expected for two different iron depletion values: δ_Fe = 0.9 in blue and δ_Fe = 0.99 in red. We assume solar abundances. Bottom: transmittance calculate taking into account solar abundance of iron (in red) and abundance expected in a region located at 1 kpc away from the Galactic centre (in blue). We fix the depletion at δ_Fe = 0.99.