Rotational velocity versus position angle of the halo of NGC 7507 in three radial bins, shown in each panel, as per the methodology described in the text. The error bars represent the RMS errors for each PA. The best fit sine curve is overplotted. Note that the Δv_r values calculated by the method described in the text are twice the actual rotational velocity. We have taken this into account so that the values shown here represent the actual rotational velocity at each PA.