G2C2-III: Structural parameters for Galactic globular clusters in SDSS
  passbands
  We use our Galactic Globular Cluster Catalog (G2C2) photometry for 111
Galactic globular clusters (GC) in g and z, as well as r and i photometry for a
subset of 60 GCs and u photometry for 22 GCs, to determine the structural
parameters assuming King (1962) models.
  In general, the resulting core radii are in good comparison with the current
literature values. However, our half-light radii are slightly lower than the
literature. The concentrations (and therefore also the tidal radii) are poorly
constrained mostly because of the limited radial extent of our imaging.
Therefore, we extensively discuss the effects of a limited field-of-view on the
derived parameters using mosaicked SDSS data, which do not suffer from this
restriction. We also illustrate how red giant branch (RGB) stars in cluster
cores can stochastically induce artificial peaks in the surface brightness
profiles. The issues related to these bright stars are scrutinised based on
both our photometry and simulated clusters. We also examine colour gradients
and find that the strongest central colour gradients are caused by central RGB
stars and thus not representative for the cluster light or colour distribution.
  We recover the known relation between the half-light radius and the
Galactocentric distance in the g-band, but find a lower slope for redder
filters. We did not find a correlation between the scatter on this relation and
other cluster properties. We find tentative evidence for a correlation between
the half-light radii and the [Fe/H], with metal-poor GCs being larger than
metal-rich GCs. However, we conclude that this trend is caused by the position
of the clusters in the Galaxy, with metal-rich clusters being more centrally
located.
