Auroral lights, August 25, 1919, observed at the Yerkes Observatory

Abstract

On 1919 August 25 before 10h 0m, 90th Meridian Time, there was a low auroral arch in the north. This was not bright nor active. At 11h 10m this arch was faint, but in the low east, south of the Pleiades, a large bright auroral light appeared in the form of an irregular cloud‐like mass several degrees wide and 10° in length (horizontally). Above this was a similar but fainter mass.