\begin{table}%t1
%\centering
\par
\caption{\label{tabella}Source parameters for some BL Lac sources.}
\par
\small
\begin{tabular}{cccccccc}
\hline\hline
Source name & $z$ &$\gamma_{\rm p}$ & $R~(\mbox{cm})$ & $B~(\mbox{G})$ & $\delta$ & $n~(\mbox{cm}^{-3})$& $r$
\\
\hline
0716+714 (low state) & $0.31$ & $3.36\times 10^3$ & $2.61\times 10^{17}$ & $1.51\times 10^{-1}$ & $10$ & $0.41$ & $1.18$
\\
0716+714 (high state) & ,, & $9.92\times 10^3$ & $7.79\times 10^{17}$ & $7.64\times 10^{-2}$ & $10$ & $0.03$ & $1.18$
\\
1ES 1553+113  & $0.25$ & $3.39\times 10^4$ & $0.64\times 10^{16}$ & $9.80\times 10^{-1}$ & $10$ & $2.04$ & $1.49$
\\
\mrkb (low state)  & $0.034$ & $1.88\times 10^5$ & $0.38\times 10^{16}$ & $9.29\times 10^{-2}$ & $15$ & $0.62$ & $0.81$
\\
\mrkb (high state) & ,, & $2.58\times 10^5$ & $0.59\times 10^{15}$ & $3.85\times 10^{-1}$ & $15$ & $23.49$ & $0.74$
\\
\hline
\end{tabular}
\end{table}