Position–velocity diagrams of the Mopra C³⁴S 2−1 (black), HC₃N 10−9 (blue), N₂H⁺ 1−0 (red), CH₃OH−A 2_0,2−1_0,1 (green), and CH₃OH−E 2_1,2−1_1,1 (pink) transitions, a) perpendicular and b) parallel to the filament. The error bars represent standard deviations (1σ). Linear fits to the velocities for each transition are shown with the same colour as in panel a).