Grey-scale image (in mJy beam⁻¹) corresponding to the radio continuum emission from the shell of G46.8–0.3 overlaid with the ¹²CO (J = 1–0) line emission from Regions A (in cyan, Δυ = 10–30 km s⁻¹, levels: 40, 70, 100 K km s⁻¹) and B (in yellow, Δυ = 30–50 km s⁻¹, levels: 55, 80, 105 K km s⁻¹) around the SNR. The velocity range of the plotted clouds is the same as in Fig. 7. The plus symbol and ellipses illustrate the best localisation and the 95%/68% confidence contours of the γ-ray emission detected by Fermi-LAT. The enclosed molecular areas corresponding to the A-10N, B-8E, and B-9C clouds were used in Sect. 6 to calculate the total proton content.