Example of the determination of the local meridian and zenith positions with data of the night on 5 January 2017 of the Pino Torinese station: (a) local meridian (solid red line) and zenith position (blue dot) on the CCD, identified by the interpolation of the stellar trajectories (black lines); (b) declination vs. x pixels of the observed crossings of the local meridian (black dots), spline interpolation (red line) and evaluation of x_Z value (blue); (c) same as (b), but for y_Z determination.