\begin{table}%t1
\renewcommand{\arraystretch}{1.25}
\caption{\label{tab1}List of the eight blazar sources in the optical
monitoring sample. }
%\begin{center}
{
\begin{tabular}{lcccccc}
\hline \hline
Object & Name & Class. & Filters & Observatory & $\gamma$-detected & Comparison Stars\\
\hline
            0219$+$428 & 3C 66A         & BL~Lac & $BVRI$ & L,S   & Yes & Fiorucci \& Tosti $(1996)^{{b}}$ \\
            0420$-$014 & PKS 0420$-$01 & FSRQ   & $VRI $ & L,S   & Yes & Smith \& Balonek (1998) \\
            0716$+$714 & S5 0716+71    & BL~Lac & $BVRI$ & B,L,S & Yes & Villata et~al. (1998a)$^{{a}}$ \\
            0735$+$178 & PKS 0735+17   & BL~Lac & $VRI $ & L,S   & Yes & Smith et~al. (1985) \\
            0851$+$202 & OJ 287         & BL~Lac & $VRI $ & L,S   & Yes & Fiorucci \& Tosti (1996) \\
            1641$+$399 & 3C 345         & FSRQ   & $VRI $ & L,S   & No  & Smith et~al. $(1985)^{{b}}$ \\
            2200$+$420 & BL~Lac         & BL~Lac & $VRI $ & L,S   & Yes & Fiorucci \& Tosti $(1996)^{{b}}$ \\
            2251$+$158 & 3C 454.3       & FSRQ   & $VRI $ & L,S   & Yes & Fiorucci et~al. (1998) \\
\hline
\end{tabular}}
\parbox{14cm}{
$^{{a}}$ $I$-data from Ghisellini et~al. (\cite{Ghisellini1997}).\\
$^{{b}}$ Magnitudes from Gonz\'{a}lez-P\'{e}rez et~al. (\cite{Gonz2001}).}
%\end{center}
\end{table}