Normalized (around the first peak) intensity profiles across the front (cut #3 of Abergel et al. 2024) averaged over 0.5^′′ perpendicular to the line cut. The illuminating star is located on the right. Top panel: intensities not corrected for extinction. Middle and bottom panels: intensities corrected for extinction using the attenuation profile derived in Sect. 4 with a parametrized extinction curve of Gordon et al. (2023) at R_V=3.1 (middle) and R_V=5.5 (bottom). The filled areas indicate uncertainties, which become particularly important after 15^′′ because the extinction estimation is uncertain due to the low signal-to-noise ratio of the NIR lines used.