Schematic illustration of the emission beam of pulsar B, modelled in this work as a pair of Gaussian components, of which the intensity profile is represented here as greyscale contours. This figure shows a 2D projection of the emission beam on the plane of the sky and the definitions of the beam parameters that were used in our model to describe the location and shape of the emission (Eq. (10); compare with Fig. C.1). The white circles at the centres of the elliptical contours show the locations of maximum beam intensity. In this representation, the observer’s LOS is perpendicular to the plane of the paper (as denoted by the circled cross). The circled dot at the top of the figure shows the direction of the magnetic axis () in this projection pointing out of the plane of the paper, towards the observer. The black and grey dotted lines show two examples of the trace of the LOS across the beam, at epochs t₁ and t₂(> t₁), respectively.