\begin{table}%t5
%\centering
\par
\caption{The relationship between temporal decay index $\alpha$, and spectral
  slopes $\beta$, for internal and external shock models.\label{table_stuff}}
\begin{tabular}{ccccccc}
\hline\hline
& & &  \multicolumn{4}{c}{Forward shock}\\
Source & $\alpha_{\rm post\mbox{-}break}$ & $\beta_{\rm post\mbox{-}break}$ &  \multicolumn{2}{c}{$p=2\beta$} & \multicolumn{2}{c}{$\alpha=(3\beta-1)/2$}\\
\hline
 \noalign{\smallskip}
GRB050126  & $\rm 1.14^{+0.08}_{-0.07}$ & $\rm 0.72^{+0.65}_{-0.60}$ &
\multicolumn{2}{c}{ $\rm 1.44^{+1.2}_{-1.2}$ } &
\multicolumn{2}{c}{ $\rm 0.58^{+0.98}_{-0.90}$ } \\
 \noalign{\smallskip}
GRB050219a & $\rm 0.75^{+0.09}_{-0.07}$ & $\rm 0.89^{+0.26}_{-0.23}$ &
\multicolumn{2}{c}{ $\rm 1.78^{+0.5}_{-0.5}$ } &
 \multicolumn{2}{c}{ $\rm 0.83^{+0.40}_{-0.34}$ } \\
\noalign{\smallskip}
\hline
 & & & \multicolumn{2}{c}{External shock} & \multicolumn{2}{c}{Internal/Reverse shock} \\
 & & & \multicolumn{2}{c}{ ($f(\nu,t)\propto
t^{-p}\nu^{-p/2}$) } & \multicolumn{2}{c}{ ($f(\nu,t)\propto
  t^{-2-\beta}\nu^{-\beta}$) } \\
 & $\alpha_{\rm pre\mbox{-}break}$  & $\beta_{\rm pre\mbox{-}break}$ & $p=2\beta$ & $\alpha=p$ & $\beta$ & $\alpha=2+\beta$ \\
\hline
\noalign{\smallskip}
GRB050126  & $\rm 2.82^{+0.55}_{-0.44}$ & $\rm 1.59^{+0.38}_{-0.35}$ & $\rm 3.18^{+0.76}_{-0.70}$ & $\rm 3.18^{+0.76}_{-0.70}$ &
$\rm 1.59^{+0.38}_{-0.35}$ & $\rm 3.59^{+0.38}_{-0.35}$ \\
 \noalign{\smallskip}
GRB050219a &  $\rm 3.17^{+0.24}_{-0.16}$ & $\rm 0.98^{+0.18}_{-0.16}$ & $\rm 1.96^{+0.36}_{-0.32}$ & $\rm 1.96^{+0.36}_{-0.32}$ &
$\rm 0.98^{+0.18}_{-0.16}$ & $\rm 2.98^{+0.18}_{-0.16}$ \\
\hline
\end{tabular} 
\end{table}