Using the Bullet Cluster as a Gravitational Telescope to Study z~7 Lyman
  Break Galaxies
  We use imaging obtained with the Hubble Space Telescope Wide Field Camera 3
to search for z_850 dropouts at z~7 and J_110 dropouts at z~9 lensed by the
Bullet Cluster. In total we find 10 z_850 dropouts in our 8.27 arcmin^2 field.
Using magnification maps from a combined weak and strong lensing mass
reconstruction of the Bullet Cluster and correcting for estimated completeness
levels, we calculate the surface density and luminosity function of our z_850
dropouts as a function of intrinsic (accounting for magnification) magnitude.
We find results consistent with published blank field surveys, despite using
much shallower data, and demonstrate the effectiveness of cluster surveys in
the search for z~7 galaxies.
