Two Example GRBs Where Fermi LAT “Extended” Data Gives a Better Photon List than “Photon”

Abstract When analyzing Fermi LAT data for temporally contained events like gamma-ray bursts (GRBs), the best data type for analyses is “Extended,” not “Photon.” Although this is already recommended by the online Fermi website, it is easy to overlook and can lead to inferior analyses. Most extended “events” that are temporally and angularly consistent with GRBs are probably photons. While preparing GRB data for other research projects, the authors encountered this counter-intuitive fact several times. The data from two GRBs are presented with a simple analysis as a demonstration.