Introduction

The Sydney University Giant Air Shower Recorder (SUGAR) was built to detect the cosmic ray air showers produced by the highest energy cosmic rays including a significant number with energies above 10¹⁹eV. Until the Pierre Auger Observatory comes into operation, it will remain the only source of information on the highest energy cosmic rays from the southern skies. The SUGAR dataset is thus uniquely valuable in pointing the way to future southern hemisphere high energy cosmic ray studies.

In preparation for the arrival of data from the Pierre Auger observatory, we wished to examine a way of looking at SUGAR data which is likely to be used in the analysis of those future data. We expected this approach to give us some insight into the practical use of such an analysis and to be of interest in giving us a new perspective on the astrophysics which already exists within the SUGAR dataset.

The approach which we took was through determining the two point angular autocorrelation function for the array directional data. We found that there was already suggestive evidence in the SUGAR data for correlations over tens of degrees in the sky and we investigated how those correlations may then be related to the sources of the highest energy cosmic rays.

© Copyright Astronomical Society of Australia 1997