\begin{table}%t3
%\centering
\par
\caption{Apparent magnitudes of objects in the filament between NGC~7603 and NGC~7603B.
The $R$-Bessel magnitude was measured for three different
epochs, the Sloan filters for only one epoch. Magnitudes in the Johnson filters and
b$_j$ photographic filter were calculated from the magnitudes in the Sloan filters (see text).
Columns 3 and 4 give the observed apparent magnitudes (uncertainty $\sim$0.2~mag.). 
Columns 5 and 6 give the same magnitudes corrected of 
Galactic extinction (Schlegel et~al. \cite{Schlegel98}) and filament extinction 
(by means of Eqs.~(\protect{\ref{extinc1}}) and
(\protect{\ref{extinc2}})).\label{var_table}} 
\begin{tabular}{ll|ll|ll} 
\hline\hline
Filter & Epoch of calculation  & Mag \#1 & Mag \#2 & Mag corr. ext. \#1 & Mag corr. ext. \#2  \\  
\hline 
Bessel $R$& June 13th, 2000   & 21.20 & 21.70 & $19.5\pm 0.7$ &    $20.9\pm 0.7$ \\ 
Bessel $R$& August 12th, 2001  & 21.09 & 21.56 & $19.4\pm 0.7$ &   $20.8\pm 0.7$ \\ 
Bessel $R$& November 30th, 2002  & 21.29 & 21.87 & $19.6\pm 0.7$ & $21.1\pm 0.7$ \\
\hline  
Sloan $u$& November 30th, 2002  & --    & 23.84 & --  & $22.2\pm 1.4$ \\
Sloan $g$& November 30th, 2002  & 23.08 & 22.89 & $20.4\pm 1.1$ & $21.6\pm 1.1$ \\
Sloan $r$& December 3rd, 2002   & 21.51 & 22.03 & $19.7\pm 0.7$ & $21.1\pm 0.7$ \\
Sloan $i$& November 30th, 2002  & 21.55 & 21.77 & $20.1\pm 0.7$ & $21.1\pm 0.7$ \\
\hline  
Johnson $U$& calc. from Sloan filters & --    &  23.35 &   --  & $21.9\pm 1.4$ \\
Johnson $B$& calc. from Sloan filters & 23.99 &  23.47 & $21.1\pm 1.1$ & $22.1\pm 1.1$ \\
Johnson $V$& calc. from Sloan filters & 22.19 &  22.39 & $20.0\pm 1.0$ & $21.3\pm 1.0$ \\
Johnson $R$& calc. from Sloan filters & 21.15 &  21.77 & $19.5\pm 0.7$ & $21.0\pm 0.7$ \\
Johnson $I$& calc. from Sloan filters & 20.99 &  21.30 & $19.9\pm 0.4$ & $20.8\pm 0.4$ \\
\hline 
b$_j$ photogr. & calc. from Johnson filters & 23.49 & 23.17 & $20.8\pm 1.1$ & $21.9\pm 1.1$ \\
\hline
\end{tabular} 
\end{table}