**Table 2:** 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.
yr	max	$\alpha$	$\delta$	v@150 pc
	(cnts)	(J2000.0)^a	(J2000.0)^b	(km s^-1)
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

^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.

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