\begin{table}%t8
\caption{\label{skyemission}Sky positions: astrometry, sky background excesses (see Sect.~\ref{nebularemission}) and mean radial velocities derived from the H$\gamma$~emission line.}   %\centering
\par
\begin{tabular}{c c c r c} 
\hline\hline \noalign{\smallskip}
id & $\alpha$ (J2000) & $\delta$ (J2000) & $\Delta_{\rm sky}$  &
$V_{\rm rad}$ \\ 
 & ($\degr$) & ($\degr$) & (\%) & (km s$^{-1}$)\\  
\hline                    
 S1  & 12.20608 & $-73.17275$ &  $ +3.8\pm 5.4 $  & $143.9\pm4.2$ \\
 S2  & 12.68487 & $-73.18533$ &  $ +13.4\pm 4.1 $ & $169.4\pm5.8$ \\ 
 S3  & 12.43554 & $-73.19611$ &  $ -5.8\pm 4.7 $  & $152.8\pm3.7$ \\ 
 S4  & 12.49946 & $-73.14372$ &  $ -4.8\pm 3.8 $  & $160.0\pm4.4$ \\ 
 S5  & 12.49446 & $-73.17817$ &  $  +0.5\pm 7.0 $ & $155.8\pm6.2$ \\ 
 S6  & 12.34712 & $-73.24400$ &  $ -11.4\pm 2.0$  & $156.0\pm3.7$ \\ 
 S7  & 12.40693 & $-73.25211$ &  $ -3.5\pm 1.5 $  & $145.2\pm5.5$ \\ 
 S8  & 12.63725 & $-73.31728$ &  $ +19.8\pm 5.4 $ & $161.9\pm2.4$ \\ 
 S9  & 12.61700 & $-73.30436$ &  $  +7.1\pm 5.5 $ & $162.2\pm6.5$ \\
 S10 & 12.60371 & $-73.21592$ &  $ -6.8\pm 3.2 $  & $161.4\pm7.3$ \\
 S11 & 12.83250 & $-73.26103$ &  $ +15.9\pm 3.8 $ & $160.9\pm6.1$ \\
 S12 & 12.48021 & $-73.10711$ &  $  +4.2\pm 3.1 $ & $141.1\pm2.7$ \\
 S13 & 12.85400 & $-73.15156$ &  $ +34.9\pm 7.3 $ & $168.2\pm6.6$ \\ 
 S14 & 12.80883 & $-73.29111$ &  $ -1.5\pm 2.7 $  & $161.0\pm3.9$ \\ 
 S15 & 12.17254 & $-73.13839$ &  $ -6.0\pm 3.4 $  & $142.8\pm2.9$ \\ 
 S16 & 12.09937 & $-73.12347$ &  $ -5.7\pm 3.0 $  & $143.2\pm1.1$ \\ 
 S17 & 12.16858 & $-73.11614$ &  $  +7.3\pm 5.5 $ & $134.9\pm2.2$ \\ 
 S18 & 12.14775 & $-73.09939$ &  $ +10.2\pm 6.1 $ & $127.1\pm1.5$ \\ 
 S19 & 11.95912 & $-73.25294$ &  $ +20.2\pm 5.2 $ & $142.1\pm4.0$ \\
 S20 & 12.01675 & $-73.22519$ &  $ +25.4\pm 11.8$ & $146.3\pm3.2$ \\ 
 S21 & 12.13529 & $-73.35828$ &  $ -2.3\pm 6.8 $  & $154.3\pm3.6$ \\ 
\hline                  
\end{tabular}
\vspace*{4mm}
\end{table}