Average of heliocentric radial velocities of member stars (see details in Sect. 4.3 and values in Table 3) for each globular cluster. Our results are plotted against those from CaT spectroscopy (Saviane et al. 2012) and Vasquez et al. (in prep.) which match well. The error bars are the standard deviation of the average. A one-to-one line is plotted to guide the eye, while radial velocities from Harris (1996, 2010 edition) are overplotted as empty circles.