Lunar Occultation Observations of Jupiter at 74 cm and 128 cm


  • Samuel Gulkis


An immersion occultation of Jupiter by the moon on October 19, 1968, UT was recorded at wavelengths of 128 cm (234 MHz) and 74 cm (405 MHz) with the 140-foot radio telescope of the National Radio Astronomy Observatory at Green Bank, West Virginia. One dimensional brightness distributions are derived from the occultation curves. They show a small asymmetry in the structure of the belts. The results have been combined with observations made at shorter wavelengths to show that there is a significant increase in the angular size of the emission at the longer wavelengths and that the relativistic electron energy spectrum must have a narrow range of energies close to the planet (∼1.5 RJ). The importance of the variation of the magnetic field strength on the radiation emitted from an ensemble of electrons trapped in a dipole field is discussed.