Median radial intensity profile (black curve) of the RCW 120 ’s shell measured perpendicular to the crest, toward the shell’s center (left) and toward the external part of the shell (right). The green error bars show the standard deviation of the mean intensity profile (same color coding for the other figures). The blue solid curve shows the effective beam profile of the ArTéMiS 350 μm data as measured on Mars. The blue dotted curve shows the best-fit Gaussian model to the observed profiles. The red dashed curve shows the best-fit Plummer model convolved with the beam.