\begin{table}%t2
\caption{{\sc nirspec} radial velocity measurements of vB~10.\label{data}}
%\centerline
 {\small \begin{tabular}{lccc}
\hline \hline
MJD & $v_{\rm r}$ & Relative $v_{\rm r}$ & $v_{\rm shift}^a$ \\
   & (km~s$^{-1}$) & (km~s$^{-1}$) & (km~s$^{-1}$) \\ 
\hline
52075.58951 &  $35.50 \pm 0.60$ &  $+$$1.13 \pm 0.30$  &  $-$$0.08 \pm 0.23$ \\  
52215.20560 &  $34.45 \pm 0.60$ &  $+$$0.08 \pm 0.30$  &  $-$$0.17 \pm 0.22$ \\  
52215.24225 &  $34.40 \pm 0.60$ &  $+$$0.03 \pm 0.30$  &  $+$$0.51 \pm 0.23$ \\
54276.55865$^b$ &  $34.37 \pm 0.30$ & -- &   -- \\   
54675.25669 &  $34.00 \pm 0.83$ &  $-$$0.37 \pm 0.53$  &  $+$$1.07\pm 0.24$ \\
\hline
\end{tabular}}
\smallskip
$^a$ Relative offset in velocity zero point, $^b$ reference epoch (see text). 
\end{table}