The Polarization, Periodicity and Angular Diameter of the Radiation from Jupiter at 610 Mc/s

Abstract

The properties of the radiation from Jupiter at 610 Mc/s (wavelength = 49 cm) have been investigated using the Royal Radar Establishment two-aerial interferometer at East–West baselines of 120 and 560 m. In addition to giving values for the flux density and the degree of polarization, the data obtained with the 120 m baseline have shown the presence of the beaming of the radiation into Jupiter's magnetic equatorial plane for the first time at a wavelength as long as 49 cm. The shape of the radiation pattern has been deduced, and found to be asymmetrical about zero magnetic declination. The observations at the 560 m baseline have enabled the equatorial diameter of the emitting region to be determined. The data have also shown a periodic variation in the projected diameter as the source oscillates due to the inclination of Jupiter's magnetic axis to the axis of rotation. This has enabled an independent value for the inclination angle to be obtained. The results, collated in Table 4, include: (a) The ‘total flux density’ (the sum of two orthogonal polarizations) for zero magnetic declination = 7.05 ± 0.20 flux units. (b) The degree of polarization for zero magnetic declination = 0.20 ± 0.02. (c) The longitude (I.A.U. System III) of the North pole = 198°.2 ± 2°.0. (d) The equatorial radio diameter (1/ e , Gaussian) = 2′ 37″ ± 10". (e) The inclination of Jupiter's magnetic axis to the axis of rotation = 10°.1 ± 1°.0.