\begin{table}
\caption{Instrumental parameters of the \HI\ observations.}
\label{tab1} %\centerline
{\begin{tabular}{lccc}
%\hline\hline\\
%\multicolumn{2}{c}{\it Low velocity resolution observations} \\
\hline \hline
Field center (J2000) & \multicolumn{2}{c}{RA~=~0$^{\rm h}$~57$^{\rm m}$~48$^{\rm s}$; Dec~=~30$^\circ$21$^{\prime}$09$^{\prime\prime}$} \\
\hline
Instrument & WSRT & VLA A-array & VLBI \\
Date of the observations & 30Jun00, 05Sep01 & 04Dec00 & 25Nov01\\
Integration time (h) & 11, 10 & 0.5 & 4.5\\
Synthesized beam (arcsec) & $35\times 18$ ($-5^\circ$)
 & $1.2\times 1.0$ (26$^\circ$)
 & $9\times 3$~mas ($-20^\circ$) \\
Number of channels & 128 & 64 & 512 \\
Bandwidth (MHz) & 10 & 6.5 & 8\\
Central frequency (MHz) & 1397.4 & 1397.4 & 1396.18 \\
Velocity resolution (\kms) & 20 & 12 & 6.0 \\
rms noise in channel maps (mJy~beam$^{-1}$) & 0.21 & 0.86 & 0.7 \\
\hline
\end{tabular}}
\end{table}