Improved Analysis of STEVE Photographs

Abstract

AbstractWe present a new approach for the analysis of high‐resolution digital camera photographs taken by photographers who have fortuitous been able to capture rare events, such as the glowing sky phenomenon known as strong thermal emission velocity enhancement (STEVE). This method is especially effective with a time lapse series of images of the night sky taken under constant camera settings with a steady pointing. Stars, planets, and satellites seen in such images can be used to determine the precise and accurate registration of camera pixels to coordinates of angular altitude and azimuth. The location of satellites in the image enables precise and accurate synchronization of the images. We apply these techniques to the series of photographs of STEVE taken on July 25, 2016. We confirm the altitude structure previously found for STEVE. We find it most likely that the green picket fence features often seen during STEVE events are produced by auroral electron precipitation. With the precipitation assumption, we are able to extract novel information about the energy spectrum of the particles responsible for the production of STEVE luminosity in this particular event. Similarly, analyses of archived digital photographs may constitute a treasure trove of important data for improved understanding of rare and transient events, such as STEVE.