\begin{table}%t4 
\caption{\label{tab:trendmags}$UBVRIz$ magnitudes of the eight field stars examined in the secular decrease of luminosity of the pulsar.}           
%\centerline
{
\begin{tabular}{c c c c c c c}
\hline\hline
Star No. & $U$ & $B$ & $V$ & $R$ & $I$ & $z$ \\
\hline
1 & 17.80 & 17.49 & 16.51 & 15.92 & 15.36 & 15.13 \\
2 & 18.43 & 17.74 & 16.36 & 15.59 & 14.87 & 14.53 \\
3 & 18.42 & 18.29 & 17.40 & 16.82 & 16.26 & 16.02 \\
4 & 18.74 & 18.32 & 17.16 & 16.48 & 15.86 & 15.59 \\
5 & 18.45 & 17.23 & 15.64 & 14.80 & 14.07 & 13.71 \\
6 & 16.56 & 16.29 & 15.37 & 14.78 & 14.22 & 13.98 \\
7 & 16.80 & 16.64 & 15.79 & 15.25 & 14.74 & 14.52 \\
9 & 18.13 & 17.93 & 17.07 & 16.51 & 15.97 & 15.75 \\
\hline
\end{tabular}} 
\medskip
 The typical errors in \textit{VRI} are 0.02~mag, while $B$, $z$ and $U$ give uncertainties of 0.03, 0.04 and 0.05 respectively. These magnitudes were estimated with the FORS1 calibrations described in Sect.~\ref{optical}. The numbering corresponds to Fig.~\ref{fig:trendstars} and Table~\ref{tab:jktlog}. 
\end{table}