2D histograms of pitch angle (x-axis, from 0° to 180°; one tick equals 45°) and magnetic field azimuthal angle (y-axis, from −180° to 180°). The entirety of histograms is structured as a matrix. In each cell, the pitch-angle histograms for the primary ISN trajectory (P) are shown, and each row of histograms is filtered for a different ϖ_inj, P. The value range for a histogram is indicated on the left line. Each histogram is labelled P to indicate that all observations were treated as coming from the primary trajectory. Each column of histograms represents a different ecliptic longitude that is indicated on the bottom line. All histograms share the same global maximum after the normalisation steps displayed in Fig. 4 were applied. The dashed lines show the range of initial pitch angles to be expected at a given magnetic field azimuthal angle. In addition, a SW filter was applied (300 km/s ≤ v_SW ≤ 450 km/s), and only data from the φ < 0° half of the instrument are shown here.