
%0 Journal Article
%A Lehany, FJ 
%A Yabsley, DE 
%T Solar Radiation at 1200 MC/S., 600 MC/S., and 200 MC/S
%J Australian Journal of Chemistry
%D 1949/03/01
%V 2
%N 1
%P 48-62
%K 
%R https://doi.org/10.1071/CH9490048
%U https://www.publish.csiro.au/paper/CH9490048 
%X Daily observations of solar radiation at frequencies of 1200 Mc/s., 600 Mc/s., and 200 Mc/s. taken between August 18 and November 30, 1947, are described. The characteristics of the radiation at 200 Mc/s. were in general agreement with those observed by earlier workers. At 600 Mc/s. and 1200 Mc/s., the received intensity was normally steady on any one day but underwent long-period variations over a range of about two to one. The radiation received when the sun was almost free of sunspots corresponded to an effective black-body temperature of 0.5 million °K. at 600 Mc/s. and 0.1 million °K. at 1200 Mc/s. As sunspots appeared, the temperature rose and showed marked oar- relation with sunspot area. It is considered that radiation at these frequencies is entirely thermal in origin and that the long-period variations are at least partly due to the influence of the magnetic field of sunspots on the mechanism of thermal emission from a magneto-ionic medium.   On a few occasions, isolated disturbances were observed on 600 Mc/s. and 1200 Mc/s. some of which were associated with chromospheric flares and radio fade-outs.   The difficulties arising in the calibration of the apparatus and the steps taken to overcome them are discussed in detail. 
