  The merging neutron star gravitational wave event GW170817 has been observed
throughout the entire electromagnetic spectrum from radio waves to
$\gamma$-rays. The resulting energetics, variability, and light curves are
shown to be consistent with GW170817 originating from the merger of two neutron
stars, in all likelihood followed by the prompt gravitational collapse of the
massive remnant. The available $\gamma$-ray, X-ray and radio data provide a
clear probe for the nature of the relativistic ejecta and the non-thermal
processes occurring within, while the ultraviolet, optical and infrared
emission are shown to probe material torn during the merger and subsequently
heated by the decay of freshly synthesized $r$-process material. The simplest
hypothesis that the non-thermal emission is due to a low-luminosity short
$\gamma$-ray burst (sGRB) seems to agree with the present data. While low
luminosity sGRBs might be common, we show here that the collective prompt and
multi-wavelength observations are also consistent with a typical, powerful sGRB
seen off-axis. Detailed follow-up observations are thus essential before we can
place stringent constraints on the nature of the relativistic ejecta in
GW170817.
