Three colour photometry of solar limb faculae

The contrasts of limb faculae at various heliocentric angles are observed in three continuum windows largely free of absorption lines. Observations with interference filters show a contrast decrease with wavelength which is not found when using an ‘UBF’ to select the shortest continuum window. Limb faculae in speckle-reconstructed images yield contrasts being typically 1.2 times higher than those deduced from the ‘best images’ of the corresponding bursts. The fit of the wavelength dependence (‘colour index’) to a black-body law is significantly better for the contrasts deduced from the reconstructed images than for the contrasts from the best images. The uncorrected contrasts yield a mean facular temperature excess of 200-300 K; those from the reconstructed images yield about 470 K. The center-to-limb variation is found to be much smaller than the fluctuations between individual faculae.