THE COSMIC-RAY GROUND-LEVEL ENHANCEMENT OF 24 OCTOBER 1989

The cosmic ray ground-level enhancement (GLE) of 24 October 1989 was t he last of a series of GLEs associated with the same solar active regi on. Intensity enhancements were observed by at least 31 neutron monito rs in the worldwide network, with the largest increase (approximately 200%) observed at South Pole, Antarctica around 20:30 UT. Using a leas t-squares model fit to all available neutron monitor data, spectra, ap parent source directions and particle pitch angle distributions have b een derived. The effect of disturbed geomagnetic conditions has also b een taken into account.