\begin{table}%t3
\caption{Best fit spectral parameters of the log-parabolic model 
for the 1997--1998 observations of Mkn~421.}
\label{tab3}
%\centerline
{
\begin{tabular}{cccccccc}
\hline  \hline
Date & $a$ & $b$ & $K$ & $E_{\rm p}$ (keV)  & ~~$\nu_{\rm p} F(\nu_{\rm p})^{(2)}$ & $F_{{\rm bol}}^{(2)}$ & $F_{2-10~{\rm keV}}^{(2)}$ \\
\hline
1997-04-29$^{(1)}$ & 2.25 (0.01)   & 0.45 (0.01)    & 7.21 (0.09) $\times$ 10$^{-2}$ & 0.53 (.02) & 1.25 (.02) & ~5.0 (.1) &  0.85 (.02)\\
1997-04-30$^{(1)}$ & 2.26 (0.01)   & 0.47 (0.01)    & 7.25 (0.09) $\times$ 10$^{-2}$ & 0.53 (.01) & 1.26 (.02) & ~5.0 (.1) &  0.83 (.02)\\
1997-05-01$^{(1)}$ & 2.23 (0.01)   & 0.43 (0.01)    & 8.21 (0.10) $\times$ 10$^{-2}$ & 0.54 (.02) & 1.41 (.02) & ~5.8 (.1) &  1.00 (.02)\\
1997-05-02$^{(1)}$ & 2.25 (0.01)   & 0.43 (0.02)    & 1.02 (0.02) $\times$ 10$^{-1}$ & 0.51 (.02) & 1.78 (.04) & ~7.3 (.2) &  1.23 (.03)\\
1997-05-03$^{(1)}$ & 2.32 (0.02)   & 0.44 (0.02)    & 6.57 (0.14) $\times$ 10$^{-2}$ & 0.43 (.03) & 1.20 (.03) & ~4.9 (.2) &  0.71 (.03)\\
1997-05-04$^{(1)}$ & 2.50 (0.02)   & 0.48 (0.02)    & 4.96 (0.13) $\times$ 10$^{-2}$ & 0.30 (.02) & 1.07 (.04) & ~4.2 (.2) &  0.41 (.02)\\
1997-05-05$^{(1)}$ & 2.40 (0.01)   & 0.45 (0.02)    & 6.47 (0.13) $\times$ 10$^{-2}$ & 0.36 (.02) & 1.27 (.03) & ~5.1 (.2) &  0.63 (.02)\\
%                   &               &                &                        &            &            &           &  \\
1998-04-21~~~      & 2.073 (0.004) & 0.344 (0.006)  & 1.88 (0.01) $\times$ 10$^{-1}$ & 0.78 (.01) & 3.04 (.02) & 13.9 (.1) &  3.10 (.02)\\
1998-04-23~~~      & 2.219 (0.004) & 0.373 (0.007)  & 1.35 (0.01) $\times$ 10$^{-1}$ & 0.51 (.01) & 2.33 (.02) & 10.3 (.1) &  1.78 (.02)\\
1998-06-22~~~      & 2.066 (0.007) & 0.341 (0.008)  & 1.44 (0.01) $\times$ 10$^{-1}$ & 0.80 (.02) & 2.32 (.02) & 10.7 (.1) &  2.39 (.02)\\
\hline
\end{tabular}}
\medskip
Errors are given at 1 sigma for one interesting parameter. \\
$^{(1)}$ ~~PDS data not included. \\
$^{(2)}$ ~~In units of 10$^{-10}$ erg cm$^{-2}$ s$^{-1}$. \\
\end{table}