Surface magnetic field distribution of CU Vir derived from Si LSD profiles. The star is shown at five rotation phases, which are indicated above the spherical plots, and the inclination angle of i = 46.5°. The spherical plots show the maps of a) field modulus, b) horizontal field, c) radial field, and d) field orientation. The contours over spherical maps are plotted with a 0.5 kG step. The thick line and the vertical bar indicate positions of the rotational equator and the pole, respectively. The colour bars give the field strength in kG. The two different colours in the field orientation map correspond to the field vectors directed outwards (red) and inwards (blue).