Gravitational radiation is properly defined only at future null infinity, but mathematically it is estimated at a finite radius, and then extrapolated. Our group developed a characteristic waveform extraction tool, implemented in an open source code, which computes the gravitational waves infinitely far from their source, in terms of compactified null cones, by numerically solving Einstein equation. We add electromagnetic waves to the null cone, by deriving a formulation of the Einstein-Maxwell equations suitable to be numerically implemented into a characteristic code, that will evolve and calculate both the gravitational waves and their electromagnetic counterparts all the way to infinity.
Babiuc, M. (2013, December). Gravitational and electromagnetic waves on the null cone. Poster session presented at the 27th Texas Symposium on Relativistic Astrophysics. Dallas, TX.