Occultation observations of compact radio sources through comet Halley's plasma tail

Enhancement in scintillations of radio sources attributable to plasma irregularities in the cometary tail have been reported for comet Kohoutek and recently for comet Halley. A set of 30 sources lying within 20 of the path of comet Halley and with a flux density of S408 > or approx., 0.8 Jy were examined, and four were found to be suitable for cometary scintillation observations. These were carried out between February and April 1986. Other scintillating sources outside the tail were monitored for comparison and, in contrast with earlier claims of positive detection, no significant increase was found in the level of turbulence that could be attributed to the plasma tail. (author)