3′× 5′ r-band image of the cluster PSZ1 G206.45+13.89 obtained with ACAM/WHT. A large gravitational arc, marked with an arrow in the plot, is clearly visible around the BCG. Circles mark the core of the main body of the cluster (to the west) and the substructure, detected in the 2D spatial distribution of galaxies and radial velocities. The box indicates the Planck PSZ1 coordinates of this SZ target.