\begin{table}%t2
 \caption{Position, proper motion, and value of the maximum corresponding to the bright spot within the D~knot evaluated from the H$_{\rm \alpha}$ images in 1996, 1998, and 2005.}
 \label{tab:spot}
   \small%\centerline
 {\begin{tabular}{lcccc}
   \hline
   \hline
   yr           & max    & $\alpha$        & $\delta$        & $v$@150~pc\\
                & (cnts) & (J2000.0)$^{a}$ & (J2000.0)$^{b}$ & (km~s$^{-1}$)\\
   \hline
   1996         & 37.2284 & 04 31 33.454 & +18 08 02.08   & -- \\
   1998         & 29.6317 & 04 31 33.422 & +18 08 01.97   & 120$^{c}$ \\
   2005         & 20.6488 & 04 31 33.336 & +18 08 01.86   & 80$^{d}$ \\
   \hline
\end{tabular}}
\medskip
 $^a$ Units of $\alpha$: hours, minutes, and seconds. \\
 $^b$ Units of $\delta$: degrees, arcminutes, and arcseconds.  \\
 $^c$ In the reference frame of the D~knot in 1998.  \\
 $^d$ In the reference frame of the D~knot in 2005.  \\
   \end{table}