  We report for the first time a method-independent geometrical expression for
the angular resolution of an arbitrary network of interferometric gravitational
wave (GW) detectors when the arrival-time of a GW is unknown. We discuss the
implications of our results on how to improve angular resolutions of a GW
network and on improvements of localization methods. An example of an
improvement to the null-stream localization method for GWs of unknown waveforms
is demonstrated.
