Fermi Gamma-ray Space Telescope

Modeling Systematic Uncertainty in GBM GRB Localizations

R. Hamburg
A. Goldstein, V. Connaughton

Abstract:

The Fermi Gamma-ray Burst Monitor (GBM) detects and localizes over 200 gamma-ray bursts (GRBs) per year, more than any other detector. Follow-up instruments utilize GBM localizations to observe GRB prompt emission and measure host galaxy redshifts, and with the gravitational wave detector Advanced LIGO coming online later this year, a coincident LIGO-GBM detection is much anticipated. However, because of uncertainty in GBM localizations, GBM localization accuracy is only on the order of degrees. This project aims to model and identify the causes of systematic uncertainty in GBM localizations. By utilizing a program that interfaces with GEANT4, a widely used code for simulating particle interactions with matter, we can investigate a localization dependence on GRB position in spacecraft coordinates. We can also compare localization accuracy to spectral model parameters and specific GRB properties, which may indicate the effect of certain GRBs on GBM?s accuracy.