Top panels: colour correction to the observed blackbody temperature compared to a non-rotating NS for a NS of constant local temperature as a function of the rotational frequency for inclination angles i= 0°, 45°, and 90° is shown by the black, red, and blue curves, respectively. The left panels correspond to radius of a non-rotating NS R = 14 km and the right panels to R = 12 km. The mass of the non-rotating NS was assumed M = 1.5 M_⊙ and both families of models have the same baryonic mass. The solid curves are for emission pattern corresponding to the isotropic intensity (4), while the dashed curves are for the electron-scattering dominated atmosphere with the intensity given by Eq. (6). The colour-correction factor is indistinguishable for the two considered emission patterns. Middle panels: correction factor to the blackbody normalization (dilution factor) as a function of the rotational frequency. Bottom panels: the correction to the bolometric flux. Same notations as in the top panels.