Infrared colours of the sources listed in Table 1. HST-detected sources are plotted in filled circles and HST non-detections in open circles. All 3.6   μm detected sources are plotted in blue dots. The colour lines track the colours of the Coleman et al. (1980) SED templates with redshift and the black lines mark the region where infrared-selected AGN are located (Stern et al. 2005). (This figure is available in color in electronic form.)