We have measured the expansion velocities and proper motion of the ansae in NGC 7009 using high dispersion echelle spectra and archive narrow band HST images .
Assuming that the ansae are moving at equal and opposite velocities from the central star we obtain an average system radial velocity of -54 \pm 2 km/s , the eastern ansa approaching and the western ansa receding at v _ { r } = 5.5 \pm 1 km/s relative to this value .
Only the proper motion of the eastern ansa could be measured , leading to 2.8 \pm 0.8 arcsec/century , or v _ { t } = ( 130 \pm 40 ) d km/s , where d is the distance to the nebula in kpc .
Additionally , the electron temperature and density for each ansa was measured using line intensity ratios .
The results are T _ { e } \sim 9000 K and n _ { e } \sim 2000 cm ^ { -3 } for both ansae within the errors .