\begin{table}%t4
\caption{\label{table:4}\label{tab4}$N_{\rm PN}$ within $m^{*}+1$, $B$~band luminosity density and surface
brightness values in the Virgo fields. In LPC, LPRX, LPS and LSF we
list the upper limits.}
\small      
%\centering
\par
\begin{tabular}{c c c c}
\hline\hline
Field & $N_{\rm PN}$  & $\Sigma$ & $\mu_{\rm B}$  \\
      & &10$^{6}$ $L_{\rm B,\odot}$ arcmin$^{-2}$ & mag arcsec$^{-2}$ \\
\hline                    
Core & 17.0    &3.1~$\pm$~0.7  & 29.0~$\pm$~0.25 \\
FCJ  & 15.0    &12.2~$\pm$~3.9 & 27.5~$\pm$~0.25 \\
LPC  & $<$$1.0$ & $<$$0.2$      & $>$$32.0 $  \\
SUBC & 14.0    &4.0~$\pm$~0.7  & 28.71~$\pm$~0.3 \\
\hline
LPRX & $< $$2.4$  &$<$$0.4$         & $>$$31.1$ \\
LPE  & 8.0      &1.5~$\pm$~0.5    & 29.8~$\pm$~ 0.35 \\ 
LPS  & $<$$ 2.4$  &$<$$0.4$         & $>$$31.1$ \\
LSF  & $<$$ 2.4$  &$<$$0.4$         & $>$$31.1$ \\
RCN1 & 13.0     &2.4~$\pm$~0.6 & 29.3~$\pm$~ 0.3 \\
SUB2 & 1.0      &0.2~$\pm$~0.2 & 31.8~$\pm$~ 1.0 \\
SUB3 & 3.0      &0.7~$\pm$~0.3 & 30.6~$\pm$~ 0.6 \\
\hline                  
\end{tabular}
\vspace*{-2mm}
\end{table}