Geometry of the toy model used to fit the harmonic variation of the timing residuals in Fig. A.1. In this figure, pulsar B spins clockwise with a spin frequency of Ω_B, and it has a velocity of v_B, directed away from the LOS. The configuration shown corresponds to ϕ_asc = 0, where the wind of pulsar A maximally deflects the emission beam of pulsar B, perpendicularly to the LOS (direction ) by angle δϕ_s. The LOS direction is defined by . In this model, the emission is assumed to be generated at a distance (r_em) from the centre of the star. The wind of pulsar A, with magnitude equal to w_⊥ (in units of r_em), deflects the emission site from position E to E′.