1· A3556 and the Radio Observations We observed the cluster of galaxies A3556 (< υ > = 14300 km/sec), belonging to the supercluster of galaxies known as the Shapley Concentration (Bardelli et al., 1994, MNRAS 267, 255, and references therein), with the Australia Telescope Compact Array. Our observations took place in the continuum band at 20 cm with the configurations 1.5D and 6C, and at 20 cm and 13 cm in the configuration 6A, for a total of 12x3 hours, with a resolution ranging from ~ 6" to ~

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... 40". We observed a sky region of ~ 2° X 1° around the cluster center taking advance of the mosaicing technique developed ATNF. These observations are part of a larger project, whose main aim is to study the interaction and evolution of clusters of galaxies located in dynamically unrelaxed environments, as is the case for A3556, deriving informations from their radio emission. Radio Emission from the Cluster Center The radio emission in A3556 is mainly concentrated around its optical center (see Fig. 1 ), characterised by a cD galaxy with an apparent magnitude my = 14.4 and by a few other luminous galaxies. Most of the bright members in the cluster have unresolved associated radio emission. The most prominent feature is the extended radio source J1324-31. The appearance of this radio source is very unusual. Our maps at various resolu-355 R. Ekers et al. (eds.), Extragalactic Radio Sources, 355-356.