\begin{table}%t1
%\centering
\par
\caption{\label{tab:fit}Twilight sky brightness fitted parameters in the
range 95$^\circ \leq\zeta\leq$ 105$^\circ$. All values are expressed
in mag arcsec$^{-2}$.}
{
\begin{tabular}{cccccc}
\hline\hline
Filter & $a_0$ & $a_1$ & $a_2$ & $\sigma$ & $\gamma$ \\
       &   & deg$^{-1}$ & deg$^{-2}$&  &  deg$^{-1}$\\
\hline
U      & 11.78 & 1.376 & $-$0.039 & 0.24 & $1.23\pm0.01$\\
B      & 11.84 & 1.411 & $-$0.041 & 0.12 & $1.24\pm0.01$\\
V      & 11.84 & 1.518 & $-$0.057 & 0.18 & $1.14\pm0.02$\\
R      & 11.40 & 1.567 & $-$0.064 & 0.29 & $1.09\pm0.03$\\
I      & 10.93 & 1.470 & $-$0.062 & 0.40 & $0.94\pm0.03$\\
\hline
\end{tabular}
}
\end{table}