Toward an Optimized Third Catalog of RHESSI TGFs

Abstract:

Gamma-ray data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite are collected one time-tagged event at a time, allowing for flexibility in how to search for terrestrial gamma-ray flashes. The second RHESSI catalog, developed at the University of Bergen (Gjesteland et al. 2012, GRL 39, L05102), found significantly more TGFs than the original catalog from the University of California (UC; Grefenstette et al. 2009, JGR 114, A02314), and was able to identify weaker flashes over the background noise. By combining the best features of these search algorithms in addition to a new algorithm developed over the past few years at UC, we have produced a second significant increase in the number of TGFs discovered, including more short events (< 100 microseconds) to which the previous algorithms were not as sensitive. We will report on the results and on the metrics we use to distinguish real events from instrumental artifacts and cosmic ray showers, both for a single TGF candidate and at the population level. Finally, we will report on the status of the RHESSI instrument after its fourth anneal to remove the effects of radiation damage, which took place in summer 2014.