\begin{table}%t1
%\centering
\par
\caption{Basic information on the VLBA observations: Col.~1: source
name (B1950); Col.~2: Observed frequency; Col.~3: Date of observations;
Col.~4: missing antenna; Cols.~5 and~6: shortest and longest projected
baselines; Cols.~7--9: beam major and minor axis and PA of
the full resolution images; Col.~10: 1$\sigma$ rms noise level on the
full resolution image plane.  
\label{taboss}}
\begin{tabular}{cccccccccc}
\hline
\hline
Source&$\nu$&Obs. date&Missing&$u_{\rm min}$&$u_{\rm max}$& &Beam& &Noise\\
B1950&GHz& &antennas&M$\lambda$&M$\lambda$ &mas&mas&$\circ$&mJy/beam\\
(1)&(2)&(3)&(4)&(5)&(6)&(7)&(8)&(9)&(10)\\
\hline
\object{B0147+400}&1.407&09/06/2004&  &0.16&41&9.3&5.3&--3&0.21\\
         &1.643&          &  &0.18&50&8.3&4.7&--4&0.38\\
         &4.543&          &  &0.49&110&2.9&1.7&--7&0.11\\
         &4.893&          &  &0.50&140&2.7&1.6&--5&0.10\\
         &8.115&          &  &0.99&230&1.7&1.0& 5&0.08\\
         &8.493&          &  &1.05&250&1.6&0.9& 5&0.07\\
\object{B0840+424}&1.407&11/24/2004&HN&0.15&40&12.0&7.5&--2&0.19\\
         &1.643&          &HN&0.18&46&10.5&6.9& 0&0.17\\
         &4.543&          &SC&0.48&110&3.5&1.9&--20&0.15\\
         &4.893&          &SC&0.50&125&3.4&1.8&--20&0.14\\
         &8.115&          &SC&0.83&210&2.0&1.6&--23&0.16\\
         &8.493&          &SC&0.88&230&2.0&1.5&--18&0.12\\
\hline
\end{tabular} 
\end{table}