  Since the gravitational wave event GW170817 and gamma-ray burst GW170817A
there have been numerous studies constraining the burst properties through
analysis of the afterglow light curves. Most agree that the burst was viewed
off-axis with a ratio of the observer angle to the jet angle
($\theta_{obs}/\theta_j$) between 4 - 6. We use a parameterized model and
broadband synchrotron data up to $\sim 800$ days post-merger to constrain
parameters of the burst. To reproduce the hydrodynamics of a gamma-ray burst
outflow we use a two-parameter "boosted fireball" model. The structure of a
boosted fireball is determined by the specific internal energy, $\eta_0$, and
the bulk Lorentz factor, $\gamma_B(\sim 1/\theta_j)$ with shapes varying
smoothly from a quasi-spherical outflow for low values of $\gamma_B$ to a
highly collimated jet for high values. We run simulations with $\gamma_B$ in
the range $1-20$ and $\eta_0$ in the range $2-15$. To calculate light curves we
use a synchrotron radiation model characterized by $F_{peak}$, $\nu_m$, and
$\nu_c$ and calculate millions of spectra at different times and $\theta_{obs}$
values using the \texttt{boxfit} radiation code. We can tabulate the spectral
parameter values from our spectra and rapidly generate arbitrary light curves
for comparison to data in MCMC analysis. We find that our model prefers a
gamma-ray burst with jet energy $E_j\sim10^{50}$ ergs and with an observer
angle of $\theta_{obs}=0.65^{+0.13}_{-0.14}$ radians and ratio to jet opening
angle of ($\theta_{obs}/\theta_j$) = 5.4$^{+0.53}_{-0.38}$.
