The Australia Telescope (a synthesis radio telescope consisting of
six 22m antennas, operated by the CSIRO's Australia Telescope National
Facility) has observed Jupiter during the UT range 0230 - 1330
from July 17 to 23 inclusive. The impacts of fragments C, D, G, K, M, N, R, V
and W, and the first limb-transit of fragment B, occurred during our
observations. Observing time was shared between 20 and 13 cm wavelength
observations studying the synchrotron radiation (Dulk, Leblanc), and 6 and 3 cm
observations with arcsecond resolution searching for disturbances at roughly
the 1-10 bar level in the Jovian atmosphere (Grossman, Muhleman, White).
At 20 cm and 13 cm, comparison has been made of rotationally-averaged maps observed from July 9 to 22. The maps differ somewhat because different Jovian longitudes are emphasized on different days, but at this stage of analysis no comet-induced changes in structure are evident.
During the impacts observations were made simultaneously at 20 and 13 cm to search for any impulsive nonthermal emission associated with the passage of the fragments through the Jovian magnetosphere. Then, during the subsequent east-limb passage of each impact site, observations were carried out at 6 and 3 cm wavelengths to look for emission from the impact plumes.
Preliminary results based on visual inspection of the real-time displays and initial analysis of the data reveal no evidence for radio emission at these wavelengths associated with any of the individual impacts, down to a flux density of approximately 10 milliJansky. However, the data are considerably more sensitive than this and further analysis to search for variations at a lower level continues. In addition, the long-term behaviour of the synchrotron flux at 20 and 13 cm will be monitored until July 29.
George Dulk (University of Colorado)
Yolande Leblanc (Observatoire de Meudon)
Stephen White (University of Maryland)