the SGB. We subtracted the background stellar contamination estimated from the star counts in the radial zone $r>1.1~r_t$. The BS seem to be more concentrated than the corresponding SGB stars only in the inner $250\div300\arcsec$ (Figure \[figbs\]). At larger distances, the BS distribution becomes less concentrated than the comparison SGB stars. We run a 2-population Kolmogorov-Smirnov test. The test does not give a particularly high statistical significance to the result: the probability that the BS and SGB stars are *not* taken from the the same distribution is 96%. However, this possibility cannot be excluded: see [@Piotto90b] and [@DP93] for a discussion on the limits in applying this statistical test for checking population gradients. Another way to look into the same problem is to investigate the radial trend of the ratio BS/SGB, as plotted in Figure \[figbs\] (*lower panel*). Also in this case the bimodal trend is quite evident. The relative number of BS stars decreases from the center of the cluster to reach a minimum at $r\simeq 250\div300$ arcsec ($r\simeq 2r_c$), and then it rises again. Again, the statistical significance is questionable, in view of the small number of BS at $r>300$ arcsec (6 stars). Nevertheless, this possible bimodality is 