Recent occurrences of stable auroral red arcs

Abstract

Stable auroral red (SAR) arcs were definitely recorded on nine occasions and possibly recorded on six other occasions at Richland, Washington, between September 1967 and mid-May 1969. A systematic program of photometric sky mapping and meridian spectrograms was used in collecting the data. The SAR arcs recorded were relatively faint, and all were accompanied by poleward auroral displays. It is clear that the SAR arcs are separate in latitude from the poleward auroras. New spectrographic evidence again verifies that [O I] 6300–6364 A is the predominant radiation of the SAR arc.