We have used the VLBA to measure the annual parallax of the H _ { 2 } O masers in the star-forming region IRAS 00420 + 5530 .
This measurement yields a direct distance estimate of 2.17 \pm 0.05 kpc ( < 3 % ) , which disagrees substantially with the standard kinematic distance estimate of \sim 4.6 kpc ( according to the rotation curve of 1 ) , as well as most of the broad range of distances ( 1.7 - 7.7 kpc ) used in various astrophysical analyses in the literature .
The 3-dimensional space velocity of IRAS 00420 + 5530 at this new , more accurate distance implies a substantial non-circular and anomalously slow Galactic orbit , consistent with similar observations of W3 ( OH ) ( 20 ; 7 ) , as well as line-of-sight velocity residuals in the rotation curve analysis of Brand & Blitz ( 1 ) .
The Perseus spiral arm of the Galaxy is thus more than a factor of two closer than previously presumed , and exhibits motions substantially at odds with axisymmetric models of the rotating Galaxy .