Lunar Occupation of a Solar Active Region at 4 cm Wavelength

Abstract

THE solar eclipse of July 20, 1963, was observed from Ann Arbor, Michigan, using the 85 ft. paraboloid telescope of the University of Michigan. As observed from Michigan the solar eclipse was partial; however, the Moon completely occulted two discrete regions on the Sun—one near the east limb and the other near the west limb. We observed the lunar occultation of the eastern region. At the 4 cm wavelength at which this occultation was observed, the pencil beam of the radio telescope had a half-power width of 5′.95 of arc. Drift scans were taken across the region before the occultation in order to find the position of the peak. These scans indicated an angular size of about 3′ of arc and a position which was in agreement with the position indicated by Stanford λ 9.1 cm maps. Thus the beam almost completely covered the discrete region, and the observations consisted in tracking the region throughout the period of occultation with the beam pointed on the peak of the region. The occultation was observed in both immersion and emersion.