Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic masers associated with massive protostars and stars in active star-forming regions. It also includes young low-mass stars from the Gould Belt region whose radio observations were performed in continuum. Based on this, most complete sample of sources to date, we have estimated the velocities $$U_{\odot}$$, $$V_{\odot}$$, $$W_{\odot}$$ and the parameters of the angular velocity of Galactic rotation $$\Omega_{0},\Omega^{(1)}_{0},\ldots,\Omega^{(4)}_{0}$$ and obtained a new estimate of the distance from the Sun to the Galactic center, $$R_{0}=8.15_{-0.20}^{+0.04}$$ kpc. The parameters of the Galactic spiral density wave have been found from the series of radial, $$V_{R}$$, and residual tangential, $$\Delta V_{\textrm{circ}}$$, velocities of stars. The amplitudes of the radial and tangential velocity perturbations are $$f_{R}=7.0\pm 0.9$$ km s$${}^{-1}$$ and $$f_{\theta}=3.8\pm 1.1$$ km s$${}^{-1}$$, the perturbation wavelengths are $$\lambda_{R}=2.3\pm 0.2$$ kpc and $$\lambda_{\theta}=2.0\pm 0.4$$ kpc, and the Sun’s phases in the spiral density wave are $$(\chi_{\odot})_{R}=-163^{\circ}\pm 9^{\circ}$$ and $$(\chi_{\odot})_{\theta}=-137^{\circ}\pm 10^{\circ}$$ for the adopted four-armed spiral pattern.

We have studied a sample of more than 25 000 young stars with proper motions and trigonometric parallaxes from the Gaia DR2 catalogue. The relative errors of their parallaxes do not exceed 10 % . The selection of stars belonging to active star-forming regions was made by Marton et al. based on data from the Gaia DR2 catalogue by invoking infrared measurements from the WISE and Planck catalogues. Low-mass T Tauri stars constitute the majority of sample stars. The following parameters of the angular velocity of Galactic rotation have been found from them: Ω_0=28.40± 0.11 km s ^-1 kpc ^-1 , Ω^'_0=-3.933± 0.033 km s ^-1 kpc ^-2 , and Ω^''_0=0.804± 0.040 km s ^-1 kpc ^-3 . The Oort constants are A=15.73± 0.32 km s ^-1 kpc ^-1 and B=-12.67± 0.34 km s ^-1 kpc ^-1 , while the circular rotation velocity of the solar neighborhood around the Galactic center is V_0=227± 4 km s ^-1 for the adopted Galactocentric distance of the Sun R_0=8.0± 0.15 kpc.