Multiple populations in Galactic globular clusters: a survey in the
  Str\"omgren system
  We are coming to believe that stellar populations in globular clusters are
not as simple as they were once thought to be. A growing amount of photometric
and spectroscopic evidence shows that globular clusters host at least two
different stellar populations. In our contribution to these proceedings we
present the first results of a survey we are conducting to look for the
presence of multiple populations in a significant number of Galactic globular
clusters, using the Str\"omgren system. We intend to photometrically separate
these populations and characterize their radial distributions and extensions.
