Characterization of Glowbug: a gamma-ray telescope for bursts and other transients

In this paper we describe the characterization of the Glowbug instrument. Glowbug is a gamma-ray telescope for gamma ray bursts (GRBs) and other transients in the 50 keV to 2 MeV band funded by the NASA Astrophysics Research and Analysis (APRA) program. Built by the U.S. Naval Research Laboratory, the instrument will be launched to the International Space Station (ISS) by the Department of Defense (DOD) Space Test Program (STP) in early 2023. Glowbug’s primary science objective is the detection and localization of short GRBs, which are the result of mergers of stellar binaries involving a neutron star with either another neutron star or a black hole. While the instrument is designed to complement existing GRB detection systems, it serves as a technology demonstrator for future networks of sensitive, low-cost gamma-ray transient detectors that provide all-sky coverage and improved localization of such events. Of greatest interest are the binary neutron star systems within the detection horizon of ground-based gravitational-wave interferometers. In a full mission life, Glowbug will detect dozens of short GRBs and provide burst spectra, light curves, and positions for gamma-ray context in multi-wavelength and multi-messenger studies of these merger events. We will present the current state of Glowbug, which will include the hardware development, calibration, environmental testing, simulations, and expected on-orbit sensitivity.