Glowbug: A gamma-ray telescope for bursts and other transients

We present the design and development status of Glowbug, a 30 keV to 2 MeV gamma-ray telescope for bursts and other transients. It is funded by the NASA Astrophysics Research and Analysis program, with an expected launch in the early 2020s. Similar in concept and sensitivity to the Fermi Gamma-ray Burst Monitor (GBM), Glowbug will join and enhance future networks of burst telescopes to increase sky coverage to Short Gamma-Ray Bursts from neutron star binary mergers, including possible bursts from neutron star-black hole mergers. Given both the discovery of the burst coincident with the gravitational wave transient GW170817, and the high observed merger rate from LIGO O3, we know such joint events occur with reasonable frequency. Expanded sky coverage in gamma rays is essential, as ground-based interferometers will deliver increasingly more detections of gravitational waves from such mergers, and finding an electromagnetic counterpart is a powerful probe of the merger dynamics.