The colour excess E_(B−V) (mag) is plotted against the distance of the observed targets (Perryman et al. 1997). Stars with distance errors larger than 50 pc are shown as squares in grey/blue. The low E_(B−V) below 120 pc indicates that there is little foreground material in front of Upper Scorpius. The increased scatter at 140  ±  20 pc reflects the density variation associated primarily with the ρ Oph cloud complex. Beyond that distance, no substantial increase of reddening is observed up to 400 pc. A similar figure for the ρ Oph cloud region was shown in Lombardi et al. (2008) (also based on optical photometry, with a partial overlap in the selected sky region).