SDSS background composite image from bands g, r, and i. LOFAR contours at 20″ resolution are overlaid in white starting at five times the rms noise and increasing by a factor of 1.4. LOFAR contours at 6″ resolution are overlaid in green starting at five times the rms noise and increasing by a factor of 1.6. Redshift coloured markers are the same as in Fig. 1. Red crosses mark the centres of mass of the two sub-clusters identified by Dahle et al. (2002).