\begin{table}%t1
%\centering
\par
\caption{Observations of NGC~5253. \textit{Exp. time} is the total exposure time (for
composite images). \textit{FWHM} is the Full Width Half Maximum of a point source.}
\label{osservazioni}
    \begin{tabular}{l c c c c c}
    \hline
    \hline
    \noalign{\smallskip}
    Filter & Instrument & Mean wav. (\AA) & Bandpass (\AA) & Exp. time (s) & {\it FWHM} \\
    \hline
    $F547M$ & WFPC2 @ HST & 5484.0 & 483.1  & 1600 & $0\farcs17$  \\
    $F656N$ & WFPC2 @ HST & 6564.0 & 21.4   & 3600 & $0\farcs17$  \\
    $F673N$ & WFPC2 @ HST & 6732.2 & 21.4   & 2400 & $0\farcs17$  \\
    $F814W$ & WFPC2 @ HST & 7921.0 & 1488.8 & 1160 & $0\farcs15$  \\
    $K$s    & ISAAC @ VLT & 21~600  & 2700   & 300  & $0\farcs40$  \\
    \hline
    \end{tabular}
\end{table}