In this paper we present the results of very long baseline interferometry ( VLBI ) observations carried out with the VLBI Exploration of Radio Astrometry ( VERA ) array and the Very Long Baseline Array ( VLBA ) toward H _ { 2 } O masers in a young planetary nebula K 3 - 35 .
From the VERA observations we measured the annual parallax and proper motion of a bright water maser spot in K 3 - 35 .
The resulting distance is D = 3.9 ^ { +0.7 } _ { -0.5 } kpc .
This is the first time that the parallax of a planetary nebula is obtained by observations of its maser emission .
On the other hand , the proper motion of K 3 - 35 as a whole was estimated to be \mu _ { \alpha } = ~ { } - 3.34 \pm 0.10 mas yr ^ { -1 } , \mu _ { \delta } = ~ { } - 5.93 \pm 0.07 mas yr ^ { -1 } .
From these results we determined the position and velocity of K 3 - 35 in Galactic cylindrical coordinates : ( R, \theta,z ) = ( 7.11 ^ { +0.08 } _ { -0.06 } kpc , 27 \pm 5 ^ { \circ } , 140 ^ { +25 } _ { -18 } pc ) and ( V _ { R } ,V _ { \theta } ,V _ { z } ) = ( 33 \pm 16 , 233 \pm 11 , 11 \pm 2 ) km s ^ { -1 } , respectively .
Additionally , from our VLBA observations we measured the relative proper motions among the water maser spots located in the central region of the nebula , which have been proposed to be tracing a toroidal structure .
The distribution and relative proper motions of the masers , compared with previous reported observed epochs , suggest that such structure could be totally destroyed within a few years , due to the action of high velocity winds and the expansion of the ionization front in the nebula .