Disc crossings of the first six Galactic BNSs, estimated using the method described in Sect. 2.2, for GC isotropy (left column, through Eq. 3) and LSR isotropy (right column, through Eq. 4). The black lines show the overplotted trajectories of the BNSs, where the dark green and dark purple regions correspond to the 68% intervals of χ₁, and the light green and light purple regions correspond to the 68% intervals for χ₂ (as given in Table 2). The dashed lines of the same colour indicate the medians in these regions. The brown plusses show τ_c , where the horizontal line extends to the 68% interval (which does not tend to be visible) and the vertical line is located at the median (which are also given in Table 2).