\begin{table}%t3 \par \caption {\label{tab:fields}The mean longitudinal magnetic field measurements for our sample of Herbig Ae/Be and debris disk stars observed with FORS~1. %In the first two columns we give the object name %and the modified Julian date of the middle of the exposures. %The measured mean longitudinal magnetic fields $\left$ %using all lines and hydrogen lines are presented in Cols.~3 and 4. } %\centerline $${\begin{tabular}{rcrr @{$~\pm~$} lr @{$~\pm~$} lc} \hline \hline \multicolumn{1}{c}{Object} & \multicolumn{1}{c}{MJD} & \multicolumn{1}{c}{SNR} & \multicolumn{2}{c}{$\left< B_z\right>_{\rm all}$} & \multicolumn{2}{c}{$\left< B_z\right>_{\rm hydr}$} & \multicolumn{1}{c}{Comm.} \\ \multicolumn{1}{c}{name} & & & \multicolumn{2}{c}{[G]} & \multicolumn{2}{c}{[G]} & \\ \hline PDS~2 & 54~610.399 & 1790 & {\bf 103} & {\bf 29} & $-$4 & 70 & ND \\ 47839 & 54~609.968 & 3375 & 134 & 52 & 141 & 62 & \\ %53179 & 54608.977 & 2190 & {\bf 73} & {\bf 11} & {\bf 93} & {\bf 14} & ND \\ %85567 & 54609.012 & 3560 & {\bf 83} & {\bf 16} & {\bf 119} & {\bf 19} & ND \\ 95881 & 54~609.993 & 3745 & 47 & 25 & 24 & 20 & \\ 97048 & 54~609.137 & 2980 & {\bf 164} & {\bf 42} & {\bf 188} &{\bf 47} & ND \\ 97300 & 54~609.047 & 2495 & 109 & 50 & 96 & 53 & \\ 100453 & 54~610.022 & 3820 & 1 & 14 & $-$30 & 28 & \\ 100546 & 54~610.046 & 4195 & {\bf 89} & {\bf 26} & {\bf 87} & {\bf 28} & ND \\ 101412 & 54~609.190 & 3280 & {\bf $-$312} & {\bf 32} & {\bf $-$454} & {\bf 42} & CD \\ & 54~610.081 & 3525 & {\bf $-$207} & {\bf 28} & {\bf $-$317} & {\bf 35} & CD \\ 135344B& 54~609.243 & 4020 & 32 & 15 & 41 & 30 & \\ & 54~610.145 & 3970 & {\bf $-$38} &{\bf 11} & {\bf $-$37} & {\bf 12} & ND \\ 139614 & 54~610.201 & 4010 & $-$40 & 25 & $-$58 & 32 & \\ 144432 & 54~609.383 & 2595 & 36 & 22 & 32 & 42 & \\ 144668 & 54~610.238 & 3710 & {\bf $-$62} & {\bf 18} & {\bf $-$92} & {\bf 27} & CD\\ 150193 & 54~609.092 & 3300 & {\bf $-$144} & {\bf 32} & {\bf $-$252} & {\bf 48} & ND \\ 152404 & 54~609.275 & 2815 & $-$107 & 37 & $-$53 & 23 & \\ 158643 & 54~609.275 & 4165 & 32 & 20 & 14 & 23 & \\ 163296 & 54~610.255 & 3535 & 40 & 30 & 105 & 40 & \\ 169142 & 54~610.175 & 3875 & 50 & 25 & 23 & 32 & \\ VV~Ser & 54~610.332 & 1050 & 200 & 75 & 376 & 141 & \\ 176386 & 54~610.272 & 3230 & {\bf $-$119} & {\bf 33} & {\bf $-$121} & {\bf 35} & ND\\ 179218 & 54~609.360 & 3855 & 51 & 30 & 28 & 34 & \\ 190073 & 54~609.410 & 3900 & {\bf 104} & {\bf 19} & {\bf 120} & {\bf 30} & CD\\ \hline \multicolumn{8}{c}{Stars with debris disks}\\ 9672 & 54~345.389 & 4365 & 50 & 22 & 42 & 32 & \\ 39060 & 53~455.193 & 4205 & $-$16 & 14 & $-$36 & 22 & \\ 109573 & 54~610.438 & 3815 & 56 & 30 & 41 & 32 & \\ 164249 & 54~610.301 & 2970 & 19 & 14 & 1 & 25 & \\ 172555 & 54~610.287 & 3875 & $-$35 & 20 & $-$31 & 28 & \\ 181327 & 54~610.364 & 3495 & $-$38 & 16 & $-$75 & 26 & \\ %strange features in spectrum of hd181327 \hline \multicolumn{8}{c}{ Standard Ap star with a weak magnetic field}\\ 162~725 & 54~549.413 & 2435 & {\bf 128} & {\bf 30} & {\bf 158} & {\bf38} & \\ \hline \end{tabular}}$$ \par \smallskip Notes: All quoted errors are 1$\sigma$ uncertainties. In Col.~6 we identify new detections by ND and confirmed detections by CD. We note that all claimed detections have a significance of at least 3$\sigma$, determined from the formal uncertainties we derive. These measurements are indicated in bold face. \end{table}