Variation in the surface temperature of the K2 star along the orbital phase. The dots show the temperature values derived individually for each spectra (blue for the 2005 season, red for the 2014–2015 spectra) by spectral synthesis. Open circles around zero phase correspond to those unaffected spectra that were observed when the white dwarf was eclipsed. The temperature rise of ≈100 K at ϕ ≈ 0.5 in both seasons may indicate the irradiation effect of the hot component (see Sect. 3.2 for details).