\begin{table}%t2
\caption{Parameters of the fitted model and their $2\sigma$ errors.
$RM_{{\rm fg}}$ is the Faraday rotation measure arising in the Milky~Way,
$R_m$ and $p_m$ are the amplitude and pitch angle of the mode with wave number~$m$, and~$\beta_m$ is the azimuth where a mode with azimuthal wave number~$m$
is maximum. The minimum value of the residual and the value of~$\chi^2$ are
shown  for each fit in the bottom lines.}\label{tab:results}
%\centering
\par
\begin{tabular}{llcccc}
\hline  \hline
  & Units & \multicolumn{4}{c}{Radial range (kpc)}  \\
  & & 6--8 & 8--10 & 10--12 & 12--14  \\
\hline 
$RM_{\rm fg}$ & $\rm{rad~m^{-2}}$ &
  $-93$~\scriptsize{$\pm5$} & $-99$~\scriptsize{$\pm5$} &
  $-93$~\scriptsize{$\pm5$} & $-89$~\scriptsize{$\pm4$} \\ 
$R_0$ & $\rm{rad~m^{-2}}$ &
  $+83$~\scriptsize{$\pm7$} & $+96$~\scriptsize{$\pm9$} &
  $+115$~\scriptsize{$\pm9$} & $+99$~\scriptsize{$\pm6$} \\ 
$p_0$ & deg &
  $-13$~\scriptsize{$\pm4$} & $-19$~\scriptsize{$\pm3$} &
  $-11$~\scriptsize{$\pm3$} & $-8$~\scriptsize{$\pm3$}  \\ 
$R_2$ &  $\rm{rad~m^{-2}}$ &
  $+45$~\scriptsize{$\pm10$} & & & \\ 
$p_2$ & deg &
  $-2$~\scriptsize{$\pm12$} & & & \\ 
$\beta_2$ & deg &
  $-43$~\scriptsize{$\pm7$} & & & \\ 
\hline 
$S$ & & $58$ & $59$ & $62$ & $62$  \\
$\chi^2$ & & $63$ & $63$ & $65$ & $65$  \\
  \hline
\end{tabular}
\end{table}