Colinearity maps for the raw and calibrated kernel phases extracted from the data, over a ±500 mas field of view. Left panel: map built from the uncalibrated kernel phases of α-Oph. Middle panel: same map built from the uncalibrated kernel phase of ϵ-Her. Right panel: colinearity map of the calibrated signal, which is the difference between the kernel phases of α-Oph and ϵ-Her. The two uncalibrated maps prominently feature the signature of the ghost present in all images in the bottom left quadrant as well as other structures at closer separations. The map of the calibrated signal on the other hand shows that most of these features are gone and reveals a positive bump on the left-hand side of the central star (for a separation of 100 mas and a position angle of 84°), which is taken as an indication of the presence of a companion.