\begin{table}%t2
\caption{The observed standard stars.\label{tab:std}}
%\centerline
{\begin{tabular}{llll}
\hline\hline 
Date & Polarized & Unpolarized & Ref.\\ dd--mm--yyyy & & &
\\[0.05in] \hline
27--08--2000 & \object{HD~155197}, \object{HD~161056},         & \object{HD~154892}  & 1 \\
           &   \object{HD~251204}, \object{BD~25\degr+727}     &           & 1 \\
28--08--2000 & \object{HD~155197}, \object{HD~161056}          & \object{HD~14069}   & 1 \\
20--03--2002 & \object{HD~126593}, \object{HD~298383} & & 1 \\
21--03--2002 & \object{HD~111579}, \object{HD~298383} & & 1 \\
22--03--2002 & \object{HD~164740}, \object{HD~298383} & & 1, 2 \\
23--03--2002 & \object{HD~111579}, \object{HD~155197} & & 1 \\
	   & \object{HD~298383} 		& & 1 \\
21--04--2002 & \object{HD~111579}, \object{HD~155197} & & 1 \\
01--05--2002 & \object{HD~155197}, \object{HD~298383} & & 1 \\
02--05--2002 & \object{HD~111579}, \object{HD~298383} & & 1 \\
25--03--2003 & \object{Hiltner 652} & & 3 \\
20--08--2003 & \object{HD~155197}, \object{HD~251204}          & \object{HD~154892}  & 1\\
21--08--2003 & \object{HD~155197}, \object{HD~126593}          &           & 1\\
22--08--2003 & \object{HD~155197}, \object{BD~25\degr+727}     & \object{HD~154892}  & 1\\
19--10--2003 & \object{HD~155197}, \object{BD~25\degr+727}     & \object{HD~64299}   & 1\\
19--10--2003 & \object{HD~155197}, \object{HD~298283}          & \object{HD~64299}   & 1\\
\hline
\end{tabular}}
\smallskip
References: (1) Turnshek et~al. ({\cite{TUR90}}); (2) Serkowski et~al. ({\cite{SER75}}); (3)~Heiles
({\cite{HEI00}}).
\end{table}