\begin{table}%t1
%\centering
\par
\newcommand{\T}{\rule{0pt}{2.6ex}}
\newcommand{\B}{\rule[-1.2ex]{0pt}{0pt}}
\caption{Observed source positions.}
\label{sourcetab}
\begin{tabular}{lccc}
\hline \hline
Source & RA (J2000) & Dec (J2000) & $v_{\rm LSR}$ \\
\hline
\T Orion KL & 05$^{\rm h}$35$^{\rm m}$14~\fs5 &
$-5$\degr 22\arcmin 30\arcsec & $+$8 \\
W51 e1/e2 & 19$^{\rm h}$23$^{\rm m}$44~\fs0 &
14\degr~30\arcmin~29\arcsec & $+$57 \\
S140 & 22$^{\rm h}$19$^{\rm m}$19~\fs1 & 63\degr 18\arcmin 50\arcsec &
$-7$ \\
\B W3(OH) & 02$^{\rm h}$27$^{\rm m}$04~\fs4 &
61\degr 52\arcmin 21\arcsec & $-$48 \\
\hline
\end{tabular}
\end{table}