  The spatial and temporal discreteness of gravitational wave sources leads to
shot noise that may, in some regimes, swamp any attempts at measuring the
anisotropy of the gravitational wave background. Cross-correlating a
gravitational wave background map with a sufficiently dense galaxy survey can
alleviate this issue, and potentially recover some of the underlying properties
of the gravitational wave background. We quantify the shot noise level and we
explicitly show that cross-correlating the gravitational wave background and a
galaxy catalog improves the chances of a first detection of the background
anisotropy with a gravitational wave observatory operating in the frequency
range (10Hz,100Hz), given sufficient sensitivity.
