Map of data counts in the full 0.5 GeV–1 TeV energy range (left) and map of excess counts obtained by subtracting from the data counts the best-fit model presented in Sect. 3.6 except for the components associated to the cocoon, namely FCES G78.74+1.56, FCES G80.00+0.50, and FCES G78.83+3.57 (right). The dashed contours correspond to the 8 µm emission from MSX data at 1.85 × 10⁻⁶ W m⁻² sr⁻¹. The contours correspond to the column density of the ionised gas template at 3.5 × 10²¹ H cm⁻². The circle and the dashed circle correspond to the position and r₆₈ of FCES G78.83+3.57 and FCES G78.74+1.56 respectively.