MAGALERT: August 27, 1978

Abstract

On August 27, 1978, a major geomagnetic storm began which eventually resulted in short period geomagnetic fluctuations of over 500 gammas in Boulder, and sightings of aurora as far south as Santa Fe, New Mexico. This storm was not obviously precipitated by flare or coronal hole solar plasma, but was apparently associated with a large solar filament which abruptly disappeared on August 23, 1978. Prelimininary results of a study inspired by this storm are that 16 of the 59 geomagnetic storms which have occurred since the beginning of the current 11 year solar cycle can only be traced to disappearing filaments and some of the other storms which have been blamed on flares or coronal holes are also associated with disappearing filaments. Filament eruptions have been identified with coronal mass ejections, especially those observed with the Skylab white-light coronograph. However, there are some points of difference between typical coronal transients and geoactive coronal transients which may suggest fruitful research.