\begin{table}%t2 %\centering \par \caption{\label{Tab_2}Summary of observations and data reduction.} \small \begin{tabular}{l r r r} \hline \hline Name of telescope & & \multicolumn{2}{c}{WSRT} \\ Total on-source integration time ($\rm h$) & $t_{\rm obs}$ & \multicolumn{2}{c}{$4\times 12$} \\ Observation dates & \multicolumn{3}{c}{19--20/12/02, 21-22/12/02, 7--8/01/03, 8--9/01/03} \\ \hline Resolution of data cube & & High & Low \\ \hline Weighting scheme & & Uniform & Robust 0.4 \\ Pixel size ($~\arcsec$) & d$x$ & $ 4 $ & $ 7 $ \\ Channel width (${\rm km}~{{\rm s}^{-1}}$) & d$v$ & $ 2.06$ & $ 4.12$ \\ Velocity resolution (${\rm km}~{{\rm s}^{-1}}$) & ${\it FWHM}_{\rm V}$ & $4.12$ & $8.24$ \\ Half-power-beam-width along the beam major axis ($~\arcsec$) & ${\it HPBW}_{\rm maj}$ & $ 13.7 $ & $ 28.4 $ \\ Half-power-beam-width along the beam minor axis ($~\arcsec$) & ${ HPBW}_{\rm min}$ & $ 12.0 $ & $ 25.6 $ \\ Beam position angle ($~\deg$) & ${\rm PA}_{\rm beam}$ & $ -0.6 $ & $ 10.6$ \\ rms noise (${\rm mJy}/{\rm beam}$) in the data cubes & $\sigma_{\rm rms}$ & $ 0.42$& $0.24$ \\ rms noise per velocity resolution element ($10^{19}~{\rm atoms}~{\rm cm}^{-2}$) & $\sigma_{\rm rms}^{N}$ & $ 1.16 $ & $ 0.30 $ \\ \hline Name of telescope/instrument & & \multicolumn{2}{c}{INT WFC} \\ Total on-source integration time ($\rm s$) & $t_{\rm obs}$ & \multicolumn{2}{c}{13~350} \\ Observing dates & & \multicolumn{2}{c}{26/02-04/03/04} \\ rms noise in the optical image (${\rm mag}~{\rm arcsec}^{-2}$) & $\sigma_{{\rm i}^\prime} $ & \multicolumn{2}{c}{$ 25.8 $} \\ rms noise in the optical image, $5~\sigma_{\rm rms}$-level for a $2\arcsec$ aperture ($\rm mag$) & $\sigma_{{\rm i}^\prime,2^{\prime\prime}} $ & \multicolumn{2}{c}{$ 21.3 $} \\ \hline \end{tabular} \end{table}