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 R _ { 0 } = 8 kpc .
We obtained the following solutions : \Omega _ { 0 } = -31.0 \pm 1.2 \mathrm { km s } ^ { -1 } \mathrm { kpc } ^ { -1 } , { \Omega _ { 0 } ^ { \prime } } = 4.46 \pm 0.21 \mathrm { km s } ^ { -1 } \mathrm { kpc } ^ { -2 } , \Omega _ { 0 } ^ { \prime \prime } = -0.876 \pm 0.067 \mathrm { km s } ^ { -1 } \mathrm { kpc } ^ { % -3 } , Oort constants : A = 17.8 \pm 0.8 km s ^ { -1 } kpc ^ { -1 } , B = -13.2 \pm 1.5 km s ^ { -1 } kpc ^ { -1 } and circular velocity of the Solar neighborhood rotation V _ { 0 } = 248 \pm 14 \mathrm { km s } ^ { -1 } .
Fourier analysis of galactocentric radial velocities of masers V _ { R } allowed us to estimate the wavelength \lambda = 2.0 \pm 0.2 kpc and peak velocity f _ { R } = 6.5 \pm 2 km s ^ { -1 } of periodic perturbations from the density wave and velocity of the perturbations 4 \pm 1 \mathrm { km s } ^ { -1 } near the location of the Sun .
Phase of the Sun in the density wave is estimated as \chi _ { \odot } \approx - 130 ^ { o } \pm 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 ) ( U _ { \odot } ,V _ { \odot } ,W _ { \odot } ) _ { \mathrm { LSR } } = ( 5.5 , 11 , 8.5 ) \pm ( 2.2 , 1.7 , 1.2 ) % \mathrm { km s } ^ { -1 } .