Enhanced detection of terrestrial gamma-ray flashes by AGILE

At the end of March 2015 the onboard software configuration of the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite was modified in order to disable the vetosignal of the anticoincidence shield for the minicalorimeter instrument. The motivation for such a change was the understanding that the dead timeinduced by the anticoincidence prevented the detection of a large fraction of Terrestrial Gamma-Ray Flashes(TGFs). The configuration change was highly successful resulting in an increase of one order of magnitude in TGF detection rate. As expected, the largest fraction of the new events has short duration (<100 μs), and part of them has simultaneous association with lightningsferics detected by the World Wide LightningLocation Network. The new configuration provides the largest TGF detection rate surface density (TGFs/km2/yr) to date, opening prospects for improved correlation studies with lightningand atmospheric parameters on short spatial and temporal scalesalong the equatorial region.