The centre of the Shapley supercluster: A3558

The Shapley supercluster is by far the largest mass cencentration in the nearbyuniverse (z<0.1). For a good mass estimate it is necessary to know the dynamicalstate of the supercluster. We propose to study the centre and at the same timethe richest cluster in the supercluster, A3558. Previous Xray observationsshowed hints for merging in this cluster. From a combined morphological andspectral analysis we want to determine the dynamical state of the cluster andestimate its mass.