\begin{table}%t1
%\centering
\par
\caption{Observed standard stars.}
\label{tab:standards}
\begin{tabular}{rl}
\hline\hline    
HR & Spectral \\
 & type \\
\hline
718 & B9 III \\
1996 & O9 V \\
3454 & B3 V \\
4468 & B9.5 V \\
4963 & A1 IV \\
5501 & B9.5 V \\
7596 & A0 III \\
8634 & B8 V \\
9087 & B7 III \\
\hline  
\end{tabular}
\end{table}