Comparison between the measured ϕ from this work and those from S19. The uncertainties on our ϕ measurements are typically of order ∼1 rad m⁻² and are not visible on the scale of this plot. The shaded region indicates 5σ of the residuals. The outliers beyond this are plotted in accordance with the explanation in the main text. Cases (i), (ii) and (iii) are plotted as red stars, circles and triangles, respectively.