\begin{table}%t5
\caption{\label{tab8}H$\alpha$ luminosity and number of ionising photons.}
\par
%\centerline
{\small
\begin{tabular}{lccc}
\hline\hline
 $R$   &  $F_{{\rm H\alpha}}$ & $L_{\rm H\alpha}$ & $Q$(H) \\
(\arcsec) & $(\rm 10^{-15} erg~cm^{-2}s^{-1})$ & $(\rm 10^{37} erg~s^{-1})$ & $(\rm 10^{49}~s^{-1})$ \\
\hline
0.00S   & $1.34\pm0.10$ & $2.61\pm0.03$ & $13.7\pm0.02$ \\
3.05S   & $1.29\pm0.10$ & $2.51\pm0.02$ & $13.2\pm0.02$ \\
6.10S   & $0.93\pm0.01$ & $1.81\pm0.03$ & $9.54\pm0.01$ \\
9.15S   & $0.60\pm0.02$ & $1.17\pm0.02$ & $6.15\pm0.02$ \\
12.20S  & $0.56\pm0.02$ & $1.09\pm0.02$ & $5.74\pm0.03$ \\
15.25S  & $0.60\pm0.02$ & $1.17\pm0.03$ & $6.15\pm0.03$ \\
18.30S  & $0.84\pm0.02$ & $1.63\pm0.02$ & $8.62\pm0.03$ \\
24.40S  & $0.80\pm0.02$ & $1.56\pm0.02$ & $8.21\pm0.01$ \\
30.50S  & $0.85\pm0.03$ & $1.65\pm0.02$ & $8.72\pm0.02$ \\
\hline
3.05N   & $0.97\pm0.01$ & $1.89\pm0.03$ & $9.95\pm0.02$ \\
6.10N   & $0.71\pm0.01$ & $1.38\pm0.03$ & $7.28\pm0.01$ \\
9.15N   & $0.66\pm0.02$ & $1.28\pm0.03$ & $6.77\pm0.01$ \\
12.20N  & $0.65\pm0.02$ & $1.26\pm0.03$ & $6.67\pm0.02$ \\
15.25N  & $0.80\pm0.02$ & $1.56\pm0.03$ & $8.21\pm0.02$ \\
18.30N  & $0.90\pm0.03$ & $1.75\pm0.03$ & $9.23\pm0.02$ \\
24.40N  & $0.51\pm0.04$ & $0.99\pm0.03$ & $5.23\pm0.01$ \\
\hline
\end{tabular}}
\medskip
\par
Notes.
 H$\alpha$ luminosity and number of ionising photons computed for the
extractions given in Col.~1.%\vspace*{-3mm}
\end{table}