A detailed dynamical analysis of the nearby rich Norma cluster ( ACO 3627 ) is presented .
From radial velocities of 296 cluster members , we find a mean velocity of 4871 \pm 54 km s ^ { -1 } and a velocity dispersion of 925 km s ^ { -1 } .
The mean velocity of the E/S0 population ( 4979 \pm 85 km s ^ { -1 } ) is offset with respect to that of the S/Irr population ( 4812 \pm 70 km s ^ { -1 } ) by \Delta v = 164 km s ^ { -1 } in the cluster rest frame .
This offset increases towards the core of the cluster .
The E/S0 population is free of any detectable substructure and appears relaxed .
Its shape is clearly elongated with a position angle that is aligned along the dominant large-scale structures in this region , the so-called Norma wall .
The central cD galaxy has a very large peculiar velocity of 561 km s ^ { -1 } which is most probably related to an ongoing merger at the core of the cluster .
The spiral/irregular galaxies reveal a large amount of substructure ; two dynamically distinct subgroups within the overall spiral-population have been identified , located along the Norma wall elongation .
The dynamical mass of the Norma cluster within its Abell radius is 1 - 1.1 \times 10 ^ { 15 } h ^ { -1 } _ { 73 } M _ { \odot } .
One of the cluster members , the spiral galaxy WKK 6176 which recently was observed to have a 70 kpc X-ray tail , reveals numerous striking low-brightness filaments pointing away from the cluster centre suggesting strong interaction with the intracluster medium .