\begin{table}%t1 \caption{\label{tab1}Log of the \vlt\ \fors\ and \forstwo\ B-band observations of \zerofour.} %\centerline { \par \begin{tabular}{lccccc} \hline\hline & Date & $N$ & $T$ (s) & $IQ$ ($\arcsec$) & Airmass \\ FORS1 & 2000-11-21 & 3 & 3600 & 0.74 (0.08)& 1.14 \\ \hline FORS2 &2006-11-25 & 5 & 2915 & 0.71 (0.10)& 1.24 \\ &2007-01-16 & 10 & 5830 & 0.93 (0.18)& 1.18 \\ &2007-01-22 & 5 &2915 & 0.82 (0.11)& 1.19 \\ &2007-02-11 & 5 & 2915 & 0.82 (0.12)& 1.30 \\ \hline \end{tabular}}\medskip \par Columns report the observing date (yyyy-mm-dd), the number of exposures ($N$) and the total integration time per night ($T$), the image quality ($IQ$) and rms (in parentheses), as computed on the image, and the airmass. Values are the average computed over the exposure sequence. \end{table}