\begin{table}%t2
\caption{X-ray luminosities of 44 Boo in the 0.3$-$2~keV and 2$-$5~keV energy bands averaged over the different observations periods and corrected for interstellar absorption. The percentage
  contribution in flux of hot plasmas ($kT \ge $ 1~keV) is indicated
  between bracketts.}\label{tab2}
%\centering
\par
\begin{tabular}{c c c c}
\hline
\hline
Obs. & $L_{\rm 0.3-2 keV}$ & $L_{\rm > 2 keV}$ & hr \\ 
            & (10$^{28}$ erg s$^{-1})$ & (10$^{28}$ erg s$^{-1}$) & \\ 
\hline
Rev. 274   & 24.3 & 2.0 & --0.85 \\
(flares) & (30\%) & (77\%) & \\
Rev. 274    & 22.4 & 1.3 & --0.89 \\     
(steady rate)   & (36\%) & (78\%) & \\
\hline
\end{tabular}
\end{table}