Accession Number : AD0709355

Title :   MICROWAVE SPECTRAL OBSERVATIONS OF CORONAL CONDENSATIONS.

Descriptive Note : Environmental research papers,

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s) : Straka,Ronald M.

Report Date : APR 1970

Pagination or Media Count : 31

Abstract : Radio coronal condensations during the 20 May 1966 and 12 November 1966 solar eclipses were measured by AFCRL at wavelengths of 3.4, 6.0, 11.1 and 21.2 cm. Almost all condensation regions showed peak flux values lower than 10 to the (-21)st power w/sq m/Hz. The flux spectra increased very slightly with increasing frequency, suggesting that thermal bremsstrahlung was the dominant emission mechanism. Only one source had a spectrum where gyromagnetic emission became dominant and caused peaking near the 6.0-cm wavelength. This source was associated with the strong bipolar spot group in McMath plage region 8573 of 12 November. A quiet-sun model that was developed to determine the source flux accounted for the east-west asymmetry, limb brightening, and polar darkening in the radio brightness distribution of the background sun. The angular size of sources was smallest, with least variations, at the 6.0-cm wavelength. Brightness temperatures of the condensations were measured at 4,700,000 degrees K (21.2 cm) during both eclipses. Flares, radio bursts, and other electromagnetic emissions originating in coronal condensation regions can cause false signatures on surveillance radars, affect satellite orbit parameters, and create ionospheric disturbances that degrade communications. Knowledge of the condensation region development is needed for early warning and prediction of potential solar disturbances. (Author)

Descriptors :   (*SOLAR CORONA, MICROWAVE SPECTROSCOPY), (*SOLAR DISTURBANCES, PREDICTIONS), SOLAR ECLIPSES, SPECTRUM ANALYZERS, BREMSSTRAHLUNG, THERMAL RADIATION, MAGNETOOPTICS, BRIGHTNESS, BACKGROUND, SOLAR FLARES, RADAR TRACKING, IONOSPHERIC DISTURBANCES

Subject Categories : Astrophysics

Distribution Statement : APPROVED FOR PUBLIC RELEASE