CO2–1 channel map as in Fig. 1, but now for a finite-width channel with a width of 0.32 km s⁻¹ (see Appendix A). Left: zero-width channel map at δv = 1.76 − 0.16 km s⁻¹. Middle: zero-width channel map at δv = 1.76 + 0.16 km s⁻¹. These are the two extreme sides of the 0.32 km s⁻¹ band. Left: low-velocity extreme. Middle: high-velocity extreme. In between, another 30 intermediate “subchannel” maps are computed. The mean of all these subchannel maps is shown to the right.