The WFPC2 UV Survey: the BSS population in NGC 5824
  We have used a combination of high-resolution Hubble Space Telescope WFPC2
and wide-field ground-based observations, in ultraviolet and optical bands, to
study the blue straggler star population of the massive outer-halo globular
cluster NGC 5824, over its entire radial extent. We have computed the center of
gravity of the cluster and constructed the radial density profile, from
detailed star counts. The profile is well reproduced by a Wilson model with a
small core (r_c \simeq 4.4 arcsec) and a concentration parameter c \simeq 2.74.
We also present the first age determination for this cluster. From the
comparison with isochrones, we have found t=13\pm0.5 Gyr. We discuss this
result in the context of the observed age-metallicity relation of Galactic
globular clusters. A total of 60 bright blue stragglers has been identified.
Their radial distribution is found to be bimodal, with a central peak, a well
defined minimum at r \sim 20 arcsec, and an upturn at large radii. In the
framework of the dynamical clock defined by Ferraro et al. (2012), this feature
suggests that NGC 5824 is a cluster of intermediate dynamical age.
