We suggest ultra-relativistic electromagnetic counterparts to gravitational waves from binary neutron star mergers at any viewing angle. Mechanisms include the merger-shock propagation accelerating smaller fraction of the neutron star surface to larger Lorentz factor beyond the escape velocity of NS, with the outer parts carrying less energy. The outflows emit synchrotron flares for seconds to years by shocking the surrounding medium. Relativistic flares shine at early ages and high energies, potentially detectable by current X-ray to radio instruments, such as Swift XRT and Pan-STARRS, and even in low ambient density ~10-3 cm-3 by EVLA. The flares probe the merger position and time, the neutron star equation of state, and the merger types as black hole-neutron star outflows would be non/mildly-relativistic. We urge numerical simulations to treat the neutron star surface precisely.
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