  We present new numerical techniques we developed for launching the first
parameter study of {\it magnetized} black hole--neutron star (BHNS) mergers,
varying the magnetic fields seeded in the initial neutron star. We found that
magnetic fields have a negligible impact on the gravitational waveforms and
bulk dynamics of the system during merger, regardless of magnetic field
strength or BH spin. In a recent simulation, we seeded the remnant disk from an
unmagnetized BHNS merger simulation with large-scale, purely poloidal magnetic
fields, which are otherwise absent in the full simulation. The outcome appears
to be a viable sGRB central engine.

High Energy Astrophysical Phenomena