Spectroscopic targets in the central region of the RX J1548.9+0851 system. Green circles indicate group members whilst red ones are background galaxies. Grey circles are spectroscopic targets without a reliable redshift. Squares show photometrically classified galaxies in the SDSS down to i′ = 21 mag. The field-of-view is  ~7 × 8 arcmin (VIMOS quadrant 3 – orientation following the CCD mask coordinates (x,y). The alignment of equatorial coordinates (N,E) is also shown). Numbers refer to the ID of Table 4.