Separation from the core for the different VLBI components for the source 1823+568 from MOJAVE data (Lister et al. 2009b). For details concerning the plot and the line fits see Lister et al. (2009b). We fit component S1 corresponding to component 4 from the MOJAVE survey. Component S1 moves fast, which may indicate that two families of VLBI components exist in the case of 1823+568. If this is the case, the nucleus of 1823+568 could contain a BBH system.