\begin{table}%t1
%\centering
\par
\caption{Time elapsed (in hours) between the start of each exposure and the 
first one, for each fiber configuration (Medusa~1 and Medusa~2).}\label{tabtime}
\begin{tabular}{c| c c}
\hline
\hline
Frame & Medusa1 & Medusa2 \\
 & \multicolumn{2}{|c}{hours} \\
\hline
1 & 0.00 & 0.00 \\
2 & 1.03 & 4.73 \\
3 & 4.75 & 5.77 \\
4 & 5.78 & 9.13 \\
\hline
\end{tabular}
\end{table}