Mean tangential ellipticity as a function of distance from the group’s center, calculated using ϵ^out − ϵⁱⁿ from simulated KiDS r-band images of GAMA groups. The input ellipticity is constructed using the measured |ϵ| for each satellite galaxy and assigning a random position angle. The output ellipticity is measured from the images, which all contain the corresponding BGG in the centre. Therefore the mean tangential ellipticity difference shows the contribution of the BGG’s stray light to the satellite’s radial alignment signal measurement.