\begin{table}%t3
 \caption{General spectroscopic properties of the knots.}
 \label{table3}
%\centerline
{
 \begin{tabular}{lcccccccccccc}
   \hline\hline
     Knot & C WHT & C INT & N WHT & N INT & 7 WHT &\#7 INT& \#1   & \#3    & \#8     &\#13    &\#14   &\#15  \\
   \hline
$-$$M_B$  & 20.61 & 20.61 & 18.06 & 18.06 & 17.60 & 17.60 & 16.34 & 17.20  &  16.46  & 17.62  & 17.07 & 15.11 \\
 $\pm$    &  0.03 &  0.03 &  0.03 &  0.03 &  0.04 &  0.04 &  0.05 &  0.03  &   0.05  &  0.05  &  0.05 &  0.08 \\
 \noalign{\smallskip}
 \noalign{\smallskip}
Slit ($\arcsec\times$ 1$\arcsec$)&5.4&12&3.6&8.4&6.0&  3.6 &  5.6  &   4.0  &   5.2   &  7.2   &  5.6  & 8.0   \\
Distance ($\arcsec$)$^a$&0&0&77.0& 77.0 &  9.8  & 10.0 & 47.6  &  35.2  &  10.9   &  10.8  &  8.0  & 19.2  \\
 \noalign{\smallskip}
 \noalign{\smallskip}
$C$(H$\beta$)$^b$&0.17& 0.25&0.17&  0.12 &  0.24 &  0.25 &  0.10 &  0.10  &   0.12  &  0.62  &  0.11 &  0.29  \\
 $\pm$    &  0.02 &  0.03 &  0.03 &  0.03 &  0.03 &  0.03 &  0.03 &  0.03  &   0.03  &  0.12  &  0.04 &  0.05  \\
 \noalign{\smallskip}
$W_{{\rm abs}}$$^{b,c}$&1.7&2.4& 0.2 &  0.9  &  2.9  &  1.5  &\nodata&\nodata &   1.1   &   2    &  5.6  &   2    \\
 $\pm$    &   0.1 &   0.3 &  0.2  &  0.2  &  0.5  &  0.3  &\nodata&\nodata &   0.3   &\nodata &  1.7  &\nodata \\
 \noalign{\smallskip}
 \noalign{\smallskip}
$T_{\rm e}[$O III$]^d$&0.71&0.74& 1.09& 1.13 & 0.77  &  0.78 & 0.82  &  0.76  &  0.88   &   0.82 &  0.86 &  0.81  \\
$T_{\rm e}[$O II$]^e$& 0.80& 0.82&1.06& 1.09 & 0.84  &  0.84 & 0.88  &  0.83  &  0.92   &   0.87 &  0.90 &  0.87  \\
$N_{\rm e}$ (cm$^{-3}$)&220& 170 &  115  &  150 & 120   &   210 &\nodata&\nodata &  150    &   120  & $<$100&$<$100  \\
 \noalign{\smallskip}
 \noalign{\smallskip}
$\Delta v_r$$^f$&0 & 0 & +117  & +110  & +118  & +122  & $-$63 &   +8   &  +125   & $-$85  & $-$70 &$-$75  \\
 $\pm$  &\nodata  &\nodata&   15   &  27   &  15   &  27   &  27   &  80    &  27     &  27    &  35   &  35   \\
 \noalign{\smallskip}
 \noalign{\smallskip}
$F$(H$\beta$)$^g$&133& 184& 4.58& 11.3  & 16.6  & 1.76  & 3.05: & 1.58:  & 6.03    & 1.92   & 8.46  & 0.94: \\
 $\pm$              & 4 &  6 & 0.16&  0.6  &  0.7  & 0.09  &\nodata&\nodata & 0.37    & 0.26   & 0.62  &\nodata \\
\noalign{\smallskip}
\noalign{\smallskip}
$W$(H$\alpha$)$^c$& 87.4 & 87.3 & 53.6 & 66.5  & 330  & 256   & 110   & 20:   & 72.0   & 30.9   & 140  & 39.7  \\
$\pm$                &  2.6 &  3.4 &  2.1 &  8.2  &  25  &  28   &  25   &\nodata&  4.5   &  2.8   &  20  &  9.5  \\
\noalign{\smallskip}
$W$(H$\beta$)$^c$ & 22.3 & 22.9 & 25.0 & 27.4  & 62.3 & 66    &\nodata&\nodata& 16.6   & 5.6    & 52   & 8.0:  \\
$\pm$                &  0.9 &  2.1 &  1.6 &  2.4  &  5.4 & 12    &\nodata&\nodata&  2.6   & 1.3    &  8   &\nodata\\
\noalign{\smallskip}
$W$(H$\gamma$)$^c$&  8.1 &  6.6 & 8.2  &  5.3  &34.3  & 20.2  &\nodata&\nodata&  8.3   &\nodata & 18   &\nodata\\
$\pm$                &  0.4 &  0.6 & 0.9  &  0.5  & 4.9  &  2.2  &\nodata&\nodata&  1.6   &\nodata &  5   &\nodata\\
\noalign{\smallskip}
$W$([O III])$^c$  & 16.7 & 20.5 & 144  & 46.6  & 116  & 63.2  &\nodata&\nodata& 25.7   & 6.8    & 42.0 & 7.8:  \\
$\pm$                &  0.6 &  0.9 &  18  &  3.7  &  9   &  3.6  &\nodata&\nodata&  2.8   & 1.2    &  3.6 &\nodata\\
\noalign{\smallskip}
\noalign{\smallskip}
Age$^h$           & 6.0  & 6.0  &  7   &  6    & 5.0  &  4.5  &  6     & 150  &  6     & 8.5    &    5  &  8.0  \\
 $\pm$               & 0.5  & 0.5  &  1   &  1    & 0.5  &  0.5  &  2     &  30  &  1     & 1.5    &    1  &  1.5  \\           
\hline
 \end{tabular}}
\medskip
 $^a$ Distance from the center of Mkn~1087. \\
 $^b$ $C$(H$\beta$) and $W_{{\rm abs}}$ calculated iteratively. See Sect.~3.2 for more details.\\
 $^c$ In \AA.\\
 $^d$ In units of $10^4$~K, calculated using empirical calibrations of \citet{P01}.\\
 $^e$ In units of $10^4$~K, $T_{\rm e} [$OII$]$ calculated from empirical calibration and the relation given by \citet{G92}.\\
 $^f$ Radial velocity with respect to the center of Mkn 1087, in~km~s$^{-1}$.  \\
 $^g$ In units of 10$\rm^{-16}$ erg s$\rm^{-1}$ cm$\rm^{-2}$ .\\
 $^h$ Estimated ages using our spectroscopical and photometric data, in Myr. See Sect.~4.1 for more details.
\end{table}