Sky area around CoRoT-11. Left: r′-filter image as retrieved from the ExoDat database. CoRoT-11 is the brightest source in the centre of the image. The nearby contaminant star, about 2″ northwest from the main target, is clearly visible. Right: image acquired by CoRoT, at the same scale and orientation. The thick line around the target delimits the photometric mask used to integrate the signal of CoRoT-11. Note how the target and the contaminant are completely blurred and blended. The crosses in the image mark the position of the stars in the field.