The ratio of umbral intensity to photospheric intensity as a function of wavelength has been studied in the case of four fairly large spots in the wavelength range 4000A - 6500A. The relative spectrophotometric gradient ...

Limb darkening observations made under excellent observing conditions are given for twenty-two wavelengths in the continuous spectrum of the sun in the region λ 3600-λ 6800; these observations were made at a time when the ...