\begin{table}%t3
\caption{\label{tab:RMmeasurements}RM measurements of SGR1806-20.}
\par
%\centering
\par
\begin{tabular}{c  c  c  c  c}
\hline\hline 
Epoch      & Days     & Frequency  & Measured             & 1 $\sigma$          \\
(2005      &  since   & (MHz)      & RM                   & error                \\
date)      & burst    &            & (${\rm rad/m^2}$) & (${\rm rad/m^2}$) \\
\hline 
Jan. 4     &  7.6     &  350       & 253.24  & 1.82  \\
Jan. 5     &  8.6     &  850       & 253.14  & 12.43 \\
Jan. 7     &  10.5    &  350       & 253.65  & 1.05  \\
Jan. 10    &  13.6    &  350       & 261.74  & 2.04  \\
\hline 
\end{tabular}
\end{table}