Polarization of the nucleus of Mrk 1018 in the Hβ–Hα spectral region. The polarization degree p_N(λ) is given in percent, the polarized flux density p_N(λ)×F_N(λ) in 10⁻¹⁷ erg s⁻¹ cm⁻² Å⁻¹, and the polarization angle θ_N(λ) in degree. Contrary to the polarization degree, the polarized flux density does not depend on the dilution by unpolarized light. These spectra were computed from the Stokes q_N(λ) and u_N(λ) binned over 30 pixels to increase the signal-to-noise ratio. The AGN direct spectrum F_A = F_N − F_Host (Fig. 2) is shown unbinned. Vertical dashed lines indicate the position of the Hβ and Hα narrow lines, and dotted lines indicate the position of major sky lines.