The technique of mapping the interplanetary medium using interplanetary scintillation (IPS) is one of the most cost-effective techniques in solar-terrestrial physics. We have continued to maintain and operate the only facility in the world capable of producing daily maps of density fluctuations in the interplanetary medium by this method, and provide a service to the community by distributing the data to research groups around the world. Collaborating groups include The Space Environment Laboratory (SEL) in Boulder, Colorado, the Rutherford Appleton Laboratory, Imperial College, the British Geological Survey and the University of California at San Diego.
SEL has continued to assess the use of the data in geomagnetic storm prediction. In collaboration with UCSD we have back-projected the solar wind maps to the solar surface so that solar wind structure can be compared with optical and soft X-ray features on the disk and in the lower corona (Hick et al. in press). Woan has presented an analysis of the most recent scintillation data, concentrating on long-lived features present during 1990--1993 and demonstrating the sensitivity of the technique to low-level global structures in the solar wind (Woan, in press).
IPS observations were interrupted between November 1993 and April 1994 to carry out an all-sky pulsar survey at 81.5MHz using the 3.6 hectare array. This work was done in collaboration with the Princeton Pulsar Group and used a novel form of data acquisition which synthesised the de-dispersing channels within DSP chips. Analysis of the data continues.
The general level of RF interference in the band 81--82MHz continues to be a concern, and during a 3 month period in 1994 no observations were possible due to transmissions from a commercial operator. Action was taken and the transmission stopped.