The inspirals and mergers of compact binaries are among the most promising
events for ground-based gravitational-wave (GW) observatories. The detection of
electromagnetic (EM) signals from these sources would provide complementary
information to the GW signal. It is therefore important to determine the
ability of gravitational-wave detectors to localize compact binaries on the
sky, so that they can be matched to their EM counterparts. We use Markov Chain
Monte Carlo techniques to study sky localization using networks of ground-based
interferometers. Using a coherent-network analysis, we find that the Laser
Interferometer Gravitational Wave Observatory (LIGO)-Virgo network can localize
50% of their ~8 sigma detected neutron star binaries to better than 50 sq.deg.
with 95% confidence region. The addition of the Large Scale Cryogenic
Gravitational Wave Telescope (LCGT) and LIGO-Australia improves this to 12
sq.deg.. Using a more conservative coincident detection threshold, we find that
50% of detected neutron star binaries are localized to 13 sq.deg. using the
LIGO-Virgo network, and to 3 sq.deg. using the LIGO-Virgo-LCGT-LIGO-Australia
network. Our findings suggest that the coordination of GW observatories and EM
facilities offers great promise.Comment: 6 pages, 4 figures, 1 table, matches published version in ApJ
(incorporates referee's comments
