Panel a: emission distribution of the ¹³CO(2–1) line in the total velocity range from –37 to –42 km s⁻¹ (white contours and blue color scale) superimposed on the IRAC-GLIMPSE images at 8.0 and 5.8 μm (red and green color scales, respectively). The contours levels are the same than those shown in the middle panel of Fig. 3. Panels b to i: channel maps of the ¹³ CO (2–1) line emission in velocity intervals of 0.7 km s⁻¹ (white contours) in the velocity range from –36.7 to –42.5 km s⁻¹ superimposed on the 8.0 and 5.8 μm (IRAC-GLIMPSE) emissions (red and green color scales) and 870 μm ATLASGAL emission (blue color scale) inside the 3 rms limit. Contours levels are 0.9 (~5.5 rms), 2.6, 4.4, 6.2, 7.9, 10, 12, 16, and 20 K km s⁻¹. The velocityinterval is indicated in the top right corner of each panel.