\begin{table}%t4
\caption{Table of Str\"omgren observations of M~55. The columns
show the central coordinates of the observed fields and the exposure
times in the different filters. Certain parts of these fields overlap
with those of the FORS2~spectroscopic observations.  }\label{photab}
 %\centering
\par
\begin{tabular}{ccccccc}
\hline\hline
Date & Field & $\alpha_{2000}$ & $\delta_{2000}$ & Exp. time($v$) [s] & Exp. time($b$) [s] & 
Exp. time($y$) [s] \\
\hline
2001/07/12 & M~55-1 & 19:40:19.0 & --30:59:30.0 & 2 $\times$ 30, 3 $\times$ 240 & 1 $\times$ 20, 2 $\times$ 90 & 3 $\times$ 10, 3 $\times$ 60 \\
2001/07/13 & M~55-2 & 19:40:19.0 & --30:53:30.0 & 1 $\times$ 30, 2 $\times$ 240 & 1 $\times$ 20, 2 $\times$ 90 & 1 $\times$ 10, 2 $\times$ 60 \\
2001/07/14 & M~55-3 & 19:39:47.1 & --30:56:01.1 & 1 $\times$ 30, 2 $\times$ 240 & 1 $\times$ 20, 2 $\times$ 90 & 1 $\times$ 10, 2 $\times$ 60 \\
\hline
\end{tabular}
\end{table}