\begin{table}%t1
\caption{Observation log. \label{tab:geo}}
%\begin{center}
{
\begin{tabular}{ccccccc}
\hline
\hline
Date & Wavelength range ($\mu$m) &$B^a$(\degds) &  $B'^{b}$(\degds) & $\alpha^{c}$(\degds) & Air mass & Solar analog star\\
\hline
2000 Oct. 6 & 0.8--2.5,2.0--4.2  & --24.14      &  --23.46        &    4.7    &  1.00--1.13 & SAO93936  \\
2000 Oct. 7 & 0.8--2.5,2.4--5.5  & --24.13      &  --23.47        &    4.6   &  1.00--1.22 & SAO93936, SAO94114  \\
2001 Dec. 8 & 0.8--2.5,2.4--5.5  & --25.85      &  --26.104        &   0.6    &  1.00--1.43 & SAO93936  \\
\hline
\end{tabular}}
\parbox{14.cm}{
{\footnotesize $^a$ Ring angle opening as seen from Earth.} \\
{\footnotesize $^b$ Ring angle opening as seen from Sun.} \\  
{\footnotesize $^c$ Phase angle.} }
%\end{center}
\par
\end{table}