Estimation of solar limb brightening at radio wavelengths from solar eclipse measurements

The center-to-limb brightness distribution of the sun at radio wavelengths gives information about the structure of the solar atmosphere. Radio telescopes have poor spatial resolution, however, and cannot provide detailed angular measurements of the brightness distribution. During a solar eclipse, the sharp edge of the moon can be used to greatly increase the angular resolution of the radio telescope in one dimension. This paper describes the technique used to estimate the brightness distribution at 3.3 mm wavelength of the solar limb from measurements made during a total eclipse. The outer edge of the sun is divided into thin concentric bands and parameteric estimation methods are used to estimate the average flux desity of each band. This approach has several advantages for inverting radiometric data, especially in scanning problems.