Mapping differential reddening in the inner Galactic globular cluster
  system
  A serious limitation in the study of many globular clusters -- especially
those located near the Galactic Center -- has been the existence of large and
differential extinction by foreground dust. In a series of papers we intend to
map the differential extinction and remove its effects, using a new dereddening
technique, in a sample of clusters in the direction of the inner Galaxy,
observed using the Magellan 6.5m telescope and the Hubble Space Telescope.
These observations and their analysis will let us produce high quality
color-magnitude diagrams of these poorly studied clusters that will allow us to
determine these clusters' relative ages, distances and chemistry and to address
important questions about the formation and the evolution of the inner Galaxy.
We also intend to use the maps of the differential extinction to sample and
characterize the interstellar medium along the numerous low latitude lines of
sight where the clusters in our sample lie. In this first paper we describe in
detail our dereddening method along with the powerful statistics tools that
allow us to apply it, and we show the kind of results that we can expect,
applying the method to M62, one of the clusters in our sample. The width of the
main sequence and lower red giant branch narrows by a factor of 2 after
applying our dereddening technique, which will significantly help to constrain
the age, distance, and metallicity of the cluster.
