Galactic Parameters from Masers with Trigonometric Parallaxes
  Spatial velocities of all currently known 28 masers having trigonometric
parallaxes, proper motion and line-of-site velocities are reanalyzed using
Bottlinger's equations. These masers are associated with 25 active star-forming
regions and are located in the range of galactocentric distances 3<R<14 kpc. To
determine the Galactic rotation parameters, we used the first three Taylor
expansion terms of angular rotation velocity {\Omega} at the galactocentric
distance of the Sun R0=8 kpc. We obtained the following solutions:
{\Omega}o=-31.0 +/- 1.2 km/s/kpc, {\Omega}o'=4.46 +/- 0.21 km/s/kpc^2,
{\Omega}o"=-0.876 +/- 0.067 km/s/kpc^3, Oort constants: A=17.8 +/- 0.8
km/s/kpc, B=-13.2 +/- 1.5 km/s/kpc and circular velocity of the Solar
neighborhood rotation Vo=248 +/- 14 km/s. Fourier analysis of galactocentric
radial velocities of masers VR allowed us to estimate the wavelength
{\lambda}=2.0 +/- 0.2 kpc and peak velocity f_R=6.5 +/- 2 km/s of periodic
perturbations from the density wave and velocity of the perturbations 4 +/- 1
km/s near the location of the Sun. Phase of the Sun in the density wave is
estimated as {\chi}o ~ -130^o +/- 10^o. Taking into account perturbations
evoked by spiral density wave we obtained the following non-perturbed
components of the peculiar Solar velocity with respect to the local standard of
rest (LSR) (Uo,Vo,Wo)LSR=(5.5,11,8.5) +/- (2.2,1.7,1.2) km/s.
