\begin{table}%t1
%\centering
\caption{Summary of observations of SX Cas.\label{tab1}}
\begin{tabular}{llccc}
\hline \hline
\noalign{\smallskip}
%\multicolumn{1}{c}{$Year$} &
\multicolumn{1}{l}{Year} &\multicolumn{1}{l}{HJD-2 400 000}
&\multicolumn{1}{c}{Filters}
%&\multicolumn{1}{c}{$Telescope$} &\multicolumn{1}{c}{$Instrument$}
&\multicolumn{1}{c}{Nights} &\multicolumn{1}{c}{$N~\rm (obs)$}\\
\hline
1981&44 867.469--44 898.370&${\it UBVRI}$&13&124 \\
1982&45 185.502--45 301.360&${\it UBVRI}$&29&252\\
1983&45 562.521--45 712.197&${\it UBVRI}$&25&254\\
1984&45 948.441--46 000.391&${\it UBVRI}$&18&142\\
2000&51 796.629--51 829.691&${\it UBVRI}$&23&184\\
2005&53 636.447--53 695.432& $B$ & 16 & 64\\
 \hline
\end{tabular}
\end{table}