  Refined astrometry measurements allow us to detect large-scale deviations
from isotropy through real-time observations of changes in the angular
separation between sources at cosmic distances. This "cosmic parallax" effect
is a powerful consistency test of FRW metric and may set independent
constraints on cosmic anisotropy. We apply this novel general test to LTB
cosmologies with off-center observers and show that future satellite missions
such as Gaia might achieve accuracies that would put limits on the off-center
distance which are competitive with CMB dipole constraints.
