The Parallax of W43: a Massive Star Forming Complex near the Galactic
  Bar
  We report trigonometric parallax measurements of masers in the massive star
forming complex W43 from VLBA observations as part of the BeSSeL Survey. Based
on measurements of three 12 GHz methanol maser sources (G029.86-00.04,
G029.95-00.01 and G031.28+00.06) and one 22 GHz water maser source
(G031.58+00.07) toward W43, we derived a distance of $5.49^{+0.39}_{-0.34}$ kpc
to W43. By associating the masers with CO molecular clouds, and associating the
clouds kinematically with CO longitude-velocity spiral features, we assign W43
to the Scutum spiral arm, close to the near end of the Galactic bar. The
peculiar motion of W43 is about 20 km/s toward the Galactic Center and is very
likely induced by the gravitational attraction of the bar.
