Solar Radiation of Wavelength 1.25 Centimetres

Abstract

Observations of solar radiation at a wavelength of 1.25 cm. and covering a period of about six months are described. The average intensity of radiation corresponded to a black-body temperature of 1.00 x 10⁴ °K. with a maximum error of about ± 5 per cent. Day-to-day variations in intensity were less than ± 3 per cent., which was the limit of observational accuracy. Short-period fluctuations were observed on a few occasions ; even during periods of intense solar activity they were not greater than ± 5 per cent. The distribution of intensity over the solar disk was measured by a method analogous to the Michelson interferometer technique and found to be consistent with 84 per cent. of the radiation coming from a uniform disk and 16 per cent. from a narrow ring around the circumference.