\begin{table}%t2
%\centering
\par
\caption{\label{sourcepos}Coordinates of observed sources.}
%\leavevmode \footnotesize
\begin{tabular}[!t]{ccc}
\hline
\hline
Source                   & RA (J2000)                                         & Dec (J2000) \\
\hline
\object{Sgr~B2}          & $17^{{\rm h}}47^{{\rm m}}21.75^{{\rm s}}$ & $-28\degr 23\arcmin 14.1\arcsec$ \\
\object{W49~N}           & $19^{{\rm h}}10^{{\rm m}}13.55^{{\rm s}}$ & $+09\degr 06\arcmin 14.7\arcsec$ \\
\object{Sgr A$^{\ast}$}  & $17^{{\rm h}}45^{{\rm m}}39.97^{{\rm s}}$ & $-29\degr 00\arcmin 23.6\arcsec$ \\
\object{NGC~7023}         & $21^{{\rm h}}01^{{\rm m}}36.91^{{\rm s}}$ & $+68\degr 09\arcmin 48.2\arcsec$ \\
\hline
\end{tabular}
\end{table}