Histograms are the probability density functions (pdfs) of line centroid velocity fluctuations ΔV = V_LSR − V₀, and the smooth curves are their approximations by Gaussians. Here V₀ is the systemic velocity component defined by the regression lines shown in Fig. 7. Panels a) and b) represent the αβ (red regression line in Fig. 7) and γ (blue regression line in Fig. 7) condensations. The lateral peaks labeled by the letters “N” and “S” correspond to the northern and southern ridges of the filament. Note the opposite chirality of the angular rotation around the horizontal axis E → W (see Sects. 3.2.2 and 3.2.4 for details).