Determination of the Solar Galactocentric distance from masers kinemics
  We have determined the Galactic rotation parameters and the solar Galactocentric distance $R_0$ by simultaneously solving Bottlinger's kinematic equations using data on masers with known line-of-sight velocities and highly accurate trigonometric parallaxes and proper motions measured by VLBI. Our sample includes 93 masers spanning the range of Galactocentric distances R from 3 to 15 kpc. The solutions found are   \Omega_0 = 29.7+/-0.5 km s^{-1} kpc^{-1},   \Omega'_0 = -4.20+/-0.11 km s^{-1} kpc^{-2},   \Omega"_0 =0.730+/-0.029 km s^{-1} kpc^{-3}, and   R_0=8.03+/-0.12 kpc. In this case, the linear rotation velocity at the solar distance R_0 is V_0=238+/-6 km s^{-1}. 
A.T. Bajkova, V.V. Bobylev
astro-ph.GA