Radial velocity (V_r), transversal velocity (V_t) and proper motion for S 269 seen from the Sun as a function of observed parallax (left plots) and distance (right plots). The contours show the distribution of sources per arm for a simulated Galactic maser distribution around the position of S 269 where the pitch angles of each arm were constant (see Sect. 4.3). The simulations were made using the code developed by Quiroga-Nuñez et al. (2017). Each single contour represents a percentage of the arm sources contained in a specific region of the plot from the inside as [0.14,0.28,0.42,0.56,0.70,0.84,0.98].