\begin{table}%T5
\caption{\label{beaming}Parameters useful to understand $\gamma$-ray loudness. Columns: (1)~source name;
(2) beaming factor $\delta$; (3) observed flux in the $0.4{-}10$~keV energy band [erg~cm$^{-2}$~s$^{-1}$];
(4) intrinsic luminosity in the $0.4{-}10$~keV energy band [erg~s$^{-1}$]; (5)~Confidence of the EGRET
detection (high~$>$$95$\%; low $<$$95$\%).} 
\small%\centering
\par
\begin{tabular}{lcccc}
\hline\hline
Source         & $\delta$  & $F$                & $L$  & Conf.\\
(1)            & (2)       & (3)                & (4)  & (5)\\
\hline
3C~$273$       & $6.5{-}7$   & $\approx$$10^{-10}$ & $\approx$$10^{46}$ & high\\
NGC~$6251$     & $3.2{-}3.8$ & $\approx$$10^{-12}$ & $\approx$$10^{43}$ & low\\
PKS~$0521-365$ & $1.4{-}3$   & $\approx$$10^{-11}$ & $\approx$$10^{42}$ & low\\
Cen~A          & $1.2{-}1.6$ & $\approx$$10^{-10}$ & $\approx$$10^{41}$ & high\\
\hline
\end{tabular}
\end{table}