\begin{table}%T7
%\centering
\par
\caption{$\lambda/\Delta \lambda_{\it FWHM}$ ratios for the 
possible astronomical features observed in the RGS-1 spectra of Mkn~421.
The instrumental resolving power is $\lambda/\Delta \lambda_{\it FWHM} < 500$.
}
\label{resol}
\begin{tabular}{cc|ccc}
\hline\hline
Feature & $\lambda$ & \multicolumn{3}{c}{$\lambda/\Delta \lambda_{\it FWHM}$} \\
number      & (\AA)   & ToO & Archival & Total \\ 
\hline 
2  & 18.680 & $\rm 780^{+190}_{-290}$ & $\rm 1230^{+160}_{-240}$ & $\rm 570^{+120}_{-150}$ \\ 
3  & 18.953 & $2370\pm300$ & $1310\pm 180$ & $\rm 680^{+100}_{-120}$ \\
7  & 21.603 & $\rm 280^{+90}_{-100}$ & $\rm 320^{+70}_{-90}$ & $270\pm50$ \\
8  & 21.823 & $3110\pm440$ & $1820\pm300$ & $3640\pm1200$ \\ 
9  & 22.778 & $2530\pm280$ & $1470\pm470$ & $\rm 3800^{+630}_{-1260}$ \\
10 & 23.510 & $370\pm70$ & $\rm 370^{+110}_{-150}$ & $\rm 330^{+50}_{-60}$ \\
\hline
\end{tabular}
\end{table}