Rotation curve in the extended solar neighbourhood traced via SEGUE stars. The thin disc stars are split into the same three metallicity bins as in Sect. 4. For each distance bin the mean rotation velocity is measured (dashed curves, additional binning in |z| applied in the range of 7 kpc < R < 9 kpc is not shown here). The circular velocity (solid curves) is calculated for the three metallicity bins. The best power-law fit of the form is shown with a black dashed line. The areas of the 1, 2 and 3σ-deviation are shown with increasingly lighter shades of grey, respectively. The solar tangential velocity v_⊙ is marked with a yellow circle.