Targets were selected in order to cover a large spread of masses (richness class 1 to 4) and redshifts (0.04 to 0.25): they constitute a sample of 16 Abell/ACO clusters.
Sufficiently nearby clusters, i.e. A195, A1035, A1045, A1126, A1413, A1468, A1781, A1831, A2034, A2245, A2312, A2457 have been observed at the Observatoire de Haute-Provence, and the results are presented in this paper. The farthest ones, A222, A223, A520, A521, have been observed using the capabilities for multi-object spectroscopy at CFHT and ESO and will be analysed in a separate paper.
The sample was a priori composed of relatively regular clusters, in order to derive "unambiguous" velocity dispersions. Nevertheless, in a few cases the velocity distribution (cf. Sect. 4) has shown evidence of subclustering, projection effects or bimodality, which obviously affect the estimate of the velocity dispersion. For this reason the three clusters A1035, A1781, A1831 with a complex velocity distribution will not be included in future in our analysis.
In addition to the spectroscopic data, we have also obtained
photometric measurements based on automatic scans of POSSII plates,
which will be presented in a forthcoming paper.