\begin{table}%t4
\caption{Best fit models to the 0.3--7 keV ACIS-I and ACIS-S  spectra of r2-3 and r2-4$^a$. Numbers in parentheses represent 90\% confidence uncertainties on the last digit.\label{cspecfit}}
%\centerline
{\begin{tabular}{lllllll} 
\hline\hline 
Observation &$\alpha_{r2-3}$ & $L_{\rm r2-3}$$^b$ & $\chi^2$/d.o.f. &$\alpha_{\rm r2-4}$  & $L_{\rm r2-4}$$^b$ & $\chi^2$/d.o.f.\\
\hline
c1 & 2.1(2) & 3.3 & 11/18 & 1.7(2) & 2.4  & 13/14 \\
c3 & $\dots$ & $\dots$ & $\dots$ & 1.4(3) &  3.9 & 16/10\\
c5 & 1.9(3) & 2.5 & 16/12 & 1.5(3) &  4.1 & 20/12\\
c7 & 2.1(4) & 2.2 & 6/9 & 1.8(3) & 2.5 & 6/11\\
c9 & 1.7(3) & 3.4 & 15/15 & 1.5(4) & 3.4 & 12/6\\
c12 & 1.7(2) & 3.0 & 20/11 & 2.3(4) & 0.9 & 6/7\\
c14 & 1.7(2) & 4.0 & 11/11 & 1.5(2) & 3.0 & 10/12\\
c15 & 1.6(2) & 4.5 & 11/16 &  1.8(2) & 3.0 & 12/11\\
c17 & $\dots$ & $\dots$ & $\dots$ & 1.6(2) & 2.0 & 11/10\\
c22 & 2.2(9) & 2.0 & 4/3 & 1.9(5) & 1.8 & 3/6 \\
c23 & 2.6(7) & 0.7 & 1/3 & 1.6(2) & 4.0 & 4/11\\
c28 & 1.8(3) & 3.8 & 8/10 & 2.2(6) & 1.9 & 10/6\\
c29 & 1.5(3) & 4.4 & 6/9 & 1.4(2) & 3.5 & 11/11\\
c31 & 2.1(3) & 3.0 & 11/9 & 1.3(2) & 3.7 & 13/9\\
c34 & 1.9(3) & 2.3 & 6/7 & 2.3(4) & 2.0 & 8.5/10\\
c35 & 2.0(4) & 2.7 & 3/7 &  1.7(3) &  3.5 & 5/7\\
\hline
\end{tabular}}
\smallskip
$^a$ {An absorbed power law model was used, with line-of-sight absorption 
$N_{\rm H}  = 1.0 \times 10^{21}$ atom cm$^{-2}$ and spectral index $\alpha$.}\\
$^b$ {0.3--10 keV luminosity/10$^{37}$ erg s$^{-1}$.}
\end{table}