Galaxy redshifts in 3 medium-distant clusters

We present results from spectroscopic observations of 3 rich and moderately distant galaxy clusters at the 3.6 m ESO telescope at La Silla. We measured 54 galaxy redshifts in 3 fields centered on the clusters A 3663 and A 3889, which are rich (R = 2) and distant (D = 6) ACO clusters, and on a new cluster, Cl 0053-37, identified on a deep plate. We present estimates of their velocity dispersion and virial mass. Cl 0053-37 had been noted as a concentration in a poor ACO cluster: S0102, with distance class D = 4. We show that Cl 0053-37 is a more distant cluster, connected to a large scale-structure at 2 similar to 0.165.