\begin{table}%t2
%\centering
\par
\caption{\label{tab:spectra}Basic data for twilight sky spectra shown in
Fig.~\ref{fig:spectra}.}
 {
\begin{tabular}{cccccc}
\hline\hline
\noalign{\smallskip}
Date       & UT start & $\Delta \lambda/\lambda$ & Alt & Az & $\varphi$ \\
           &              & \AA ({\it FWHM})               & deg & deg & deg \\
\hline
2001-09-21 & 10:06:58 & 130 & 82.6 &117.5 & 6.5 \\ 
2003-11-29 & 09:02:25 & 13 & 65.8 &122.9 & 9.4 \\ 
2003-02-28 & 09:45:52 & 16 & 27.5 &299.3 & 11.9 \\ 
1999-04-16 & 09:54:36 & 12 & 41.1 &233.4 & 14.8 \\
\hline
\end{tabular}
}
\end{table}