Comparison of the measurements and best-fit values for the cluster “A” (left panels) and clusters “B” + “C” (right panels). Upper and lower panels refer to the velocities (projected along the cluster major-axis) and the l.o.s. accelerations, respectively. Red crosses and errorbars give the measurements and corresponding errors, plotted vs. the maser position. The black dashed line shows the change of the model-predicted quantities along the maser pattern, with black crosses denoting the values in correspondence of the maser positions.