\begin{table}%t11
\caption{Features in the difference spectrum of the 1999 and 2002 LETGS~data. We list Gaussian centroids~$\lambda$ (in the restframe of NGC~5548), $\sigma$ and peak value~$p$; peaks are
expressed as a fraction of the 2002~spectrum at the same energy.}\label{tab:timdif}
%\centering
\par
\begin{tabular}{llr}
\hline \hline
$\lambda$ (\AA) & $\sigma$ (\AA) & \multicolumn{1}{c}{$p$} \\
\hline
16.10 $\pm$ 0.06 & $\rm 0.10^{+0.09}_{-0.04}$ & $-$0.25 $\pm$ 0.09 \\
22.36 $\pm$ 0.02 & 0.03 $\pm$ 0.02          & $+$0.85 $\pm$ 0.29 \\
27.18 $\pm$ 0.07 & $\rm 0.08^{+0.07}_{-0.05}$ & $-$0.27 $\pm$ 0.12 \\
34.13 $\pm$ 0.08 & 0.12 $\pm$ 0.07          & $+$0.34 $\pm$ 0.14 \\
\hline
\end{tabular}
\end{table}