The Radio Spectrum of Solar Activity

Observations of the solar radio spectrum have been made at the Harvard Radio Astronomy Station, Fort Davis, Texas, daily from sunrise to sunset since September, 1956. The equipment comprises three separate receivers covering the total range 100-580 mc, and these are attached to a 28-foot-diameter paraboloid antenna. The outputs of the receivers are displayed on intensity modulated, high resolution cathode-ray tubes, and these are photographed by a continuous motion camera. Over-all, the system is approximately ten times more sensitive than any sweep frequency equipments used previously for solar observations. Examples of the records showing the four main types of radiation from active areas on the sun are given, and brief comments are made on the existing theories to account for them.