Map of FUGIN ¹²CO (J = 1–0) line emission in the region surrounding PSR J1809−1917 (Umemoto et al. 2017). Contour lines at 40 K km s⁻¹ and 80 K km s⁻¹ are shown in black and dark grey, respectively. The lines at 40 K km s⁻¹ are also displayed in Fig. 2(b). The black triangle marker denotes the position of PSR J1809−1917, light blue circles show the positions of SNRs, and the grey dashed line marks the Galactic plane. The position and 1-σ extent of component A and component B of HESS J1809−193 are displayed in green and purple, respectively.