Blended source confidence (BSC) curve from the AstraLux SDSSz image (solid black line). The colour on each angular separation and contrast bin represent the probability of a source aligned at the location of the target, based on the TRILEGAL model. The horizontal dotted line shows the maximum contrast of a blended binary that is capable of imitating the planet’s transit depth. The green region represents the regime that is not explored by the high-spatial resolution image. The BSC curve corresponds to the integration of P_aligned over this region.