\begin{table}%t1
\caption{\label{Tab1}Magnitudes of reference stars in the SN~field. The rms of the average magnitudes are reported in~brackets.}
%\centering
\small
\begin{tabular}{ccccc}
\hline \hline
Star & $B$ & $V$ & $R$ & $I$  \\ 
\hline
1 & 17.55 (0.02) & 16.55 (0.01) & 15.89 (0.02) & 15.18 (0.02) \\ 
2 & 20.02 (0.02) & 18.48 (0.01) & 17.52 (0.01) & 16.37 (0.02) \\
3 & 18.29 (0.03) & 16.84 (0.01) & 15.92 (0.05) & 15.05 (0.03) \\
4 & 19.45 (0.02) & 18.73 (0.01) & 18.23 (0.01) & 17.73 (0.02) \\ 
5 & 18.82 (0.01) & 18.05 (0.01) & 17.59 (0.01) & 17.09 (0.01) \\
6 & 20.33 (0.02) & 18.76 (0.01) & 17.77 (0.01) & 16.71 (0.02) \\
7 & 20.03 (0.01) & 19.15 (0.02) & 18.57 (0.01) & 18.08 (0.02) \\
8 & 19.41 (0.04) & 18.21 (0.03) & 17.38 (0.04) & 16.80 (0.03) \\
9 &              & 20.36 (0.04) &              & 18.05 (0.02) \\
\hline
\end{tabular}
\end{table}