2009ApJ...693..397R

We are conducting a large program with the NRAO Very Long Baseline Array (VLBA) to measure trigonometric parallaxes of massive star-forming regions across the Milky Way. Here we report measurement of the parallax and proper motion of methanol masers in S 252 and G232.6+1.0. The parallax of S 252 is 0.476±0.006 mas (2.10^+0.027_–0.026kpc), placing it in the Perseus spiral arm. The parallax of G232.6+1.0 is 0.596±0.035 mas (1.68^+0.11 _–0.09kpc), placing it between the Carina-Sagittarius and Perseus arms, possibly in a Local (Orion) spur of the Carina-Sagittarius arm. For both sources, kinematic distances are significantly greater than their parallax distances. Our parallaxes and proper motions yield full space motions accurate to ~1 km/s. Both sources orbit the Galaxy ∼13 km/s slower than circular rotation.