Top panel: best fit obtained with the vertical density profile of SOIR for the latitude + 49° and an aerosol scale height H = 4.8 km using the multilayer refractive model. Bottom panel: altitude of the highest layer probed by the aureole as a function of f (blue solid line). The maximum altitude corresponds to the tangent limb geometry at which the source of the light ray reaching the observer is the solar limb. Above this altitude, the deviation by refraction is too small to deflect sunlight toward the observer at + 49°. The gray gradient represents the scale height of the aerosols (H = 4.8 km) used in model 2. The dark line represents τ = 1.