  The first, long awaited, detection of a gravitational wave (GW) signal from
the merger of a binary neutron-star (NS-NS) system was finally achieved
(GW$\,$170817), and was also accompanied by an electromagnetic counterpart --
the short-duration GRB 170817A. It occurred in the nearby ($D\approx40\;$Mpc)
elliptical galaxy NGC$\,$4993, and showed optical, IR and UV emission from half
a day up to weeks after the event, as well as late time X-ray (at $\geq
8.9\;$days) and radio (at $\geq 16.4\;$days) emission. There was a delay of
$\Delta t \approx 1.74\;$s between the GW merger chirp signal and the
prompt-GRB emission onset, and an upper limit of $\theta_{\rm obs}<28^\circ$
was set on the viewing angle w.r.t the jet's symmetry axis from the GW signal.
In this letter we examine some of the implications of these groundbreaking
observations. The delay $\Delta t$ sets an upper limit on the prompt-GRB
emission radius, $R_\gamma\lesssim 2c\Delta t/(\theta_{\rm obs}-\theta_0)^2$,
for a jet with sharp edges at an angle $\theta_0<\theta_{\rm obs}$. GRB
170817A's relatively low isotropic equivalent $\gamma$-ray energy-output may
suggest a viewing angle slightly outside the jet's sharp edge,
$\theta_{\rm{}obs}-\theta_0\sim(0.05-0.1)(\Gamma/100)^{-1}$, but its peak
$\nu{}F_\nu$ photon energy and afterglow emission suggest instead that the jet
does not have sharp edges and the prompt emission was dominated by less
energetic material along our line of sight, at $\theta_{\rm{}obs}\gtrsim
2\theta_0$. Finally, we consider the type of remnant that is produced by the
NS-NS merger and find that a relatively long-lived ($>2\;$s) massive NS is
strongly disfavored, while a hyper-massive NS of lifetime $\sim1\;$s appears to
be somewhat favored over the direct formation of a black hole.
