Median of the central velocity of the NH₃ (1, 1) line for points across the filament, as a function of position along the blue filament (blue dots) and the red filament (red dots). The two slices used are the same as in Fig. 11. The error bars indicate the median of the uncertainty of the values of the central velocity. The range of values is typically three times the median uncertainty. The dashed linesindicate the velocity gradients along the filaments. They are labeled “1” for the blue filament and “2” and “3” for the red filament. The same labels are used in Fig. 20.