Angles vs. distance plot for Field B. The angle on the y-axis denotes the polarisation angle of the stars as well as the angle distribution of the depolarisation canals. The x-axis denotes the distance to the stars. Horizontal red lines mark the averages of distinctive orientations of the depolarisation canals, and light blue areas span the spread of the distributions for the corresponding averaged values, the same as in Fig. 5 with two peaks ~ 100° apart. The colours of the stars correspond to the same groups of stars shown in Fig. 9. We can freely shift the polarisation angles of the stars modulo π, meaning that the three stars plotted near 90° could also belong to the area below − 90° around the negative peak of the angle distribution of the depolarisation canals. The horizontal black line marks the average true value of the polarisation angle for the background stars, and the grey area spans the error range.