Images cutouts of the 12 serendipitous lines used to build the [C II] LF. The HST-ACS 0.78 μm (Koekemoer et al. 2007, 2011) and Spitzer–IRAC 4.5 μm (Capak et al. 2012) are reported. The white contour shows the [C II] emission in steps of 2σ (lowest level at 3σ). We indicate with a white cross the location of the serendipitous detection while the red cross shows the position of the central target. We can see that for 6 out of 12 lines the distance between the central target and the serendipitous line is < 3″, hence, there is a possibility that we are witnessing interacting systems. For S5100822662, the [C II] emission is blended with that of the central target.