Accession Number : AD0428675

Title :   OCCULTATION OF THE CRAB NEBULA BY THE SOLAR CORONA IN JUNE 1963,

Corporate Author : CALIFORNIA INST OF TECH PASADENA OWENS VALLEY RADIO OBSERVATORY

Personal Author(s) : Wyndham,J. D. ; Clark,B. G.

Report Date : JUN 1963

Pagination or Media Count : 4

Abstract : Observations of the Crab Nebula were undertaken in June 1963 using the twin 90-ft dishes of the California Institute of Technology's Owens Valley Radio Observatory. The two antennae were employed as an east-west interferometer of spacing 680 wavelength operating at a frequency of 1660 Mc/s (18 cm wavelength). Any increase in angular diameter of the source, observed with interferometer, results in a decrease in the recorded source response which may be interpreted directly in terms of the angular extent of the scattered distribution. The quiet sun was largely resolved and gave a contribution to the total response which was only a fraction of the response due to the source itself. In the absence of an appreciable solar contribution it was possible to detect scattering angles as small as 0.7. In order to allow for the solar contribution, additional observations of the response were made each day with the antennae directed towards the positions which the source took relative to the sun on each of the occulting days. As the angular separation of source and sun decreased, the gain was decreased by measured amounts (always less than 0.4 db) to preserve the same detector levels in the presence of solar noise. The response of the source 3C 123 was observed each day and used to correct for small changes in receiver sensitivity. When the above factors were taken into account in the anaylsis, no positive evidence for a variation in the source response, corresponding to an increase in angular diameter, was found. (Author)

Descriptors :   (*NEBULAE, SOLAR CORONA), SCATTERING, ELECTRONS, RADIO INTERFEROMETERS

Distribution Statement : APPROVED FOR PUBLIC RELEASE