Top panel: A (ΔRA, v_los) diagram presenting the FFs (red circles), the PNe associated with the companion NGC 1023A (stars) and the ones associated to the stream (squares) firstly reported by Cortesi et al. (2011). The H i map (Morganti et al. 2006), obtained by collapsing a masked version of the H i cube along the declination axis is the blue shaded distribution. Bottom panel: the same as the top panel, but showing the FFs (red circles), the spheroid (green squares) and disc (blue triangles) PNe belonging to NGC 1023. Note that the dimension of the symbol of the FFs is proportional to their R_eff, but not scaled to the figure. For NGC 1023, 1″= 50 pc.