Performance Modeling and Improvements on the GRB Source Localization Streaming Pipeline Aboard the Antarctic Demonstrator for the Advanced Particle-Astrophysics Telescope (ADAPT)

The Advanced Particle-astrophysics Telescope (APT) is a mission concept for a space-based gamma-ray telescope whose capabilities include prompt localization of gamma-ray bursts (GRBs) to support multi-wavelength and multi-messenger astrophysics. ADAPT — APT’s balloon-borne prototype — can localize GRBs in well under a second using on-board computing hardware. ADAPT will partner with ground-based, fast-slewing optical telescopes, rapidly providing alerts that enable the partner to observe a short-duration burst within a few seconds of detection. In this work, we investigate the utility of having ADAPT issue progressively more accurate location estimates for a GRB as detected Compton events from the burst accumulate over time. We develop a computational model to estimate how frequently ADAPT can compute these estimates, finding that it can do so at least every 150 ms for a 1 MeV/cm2 burst on a low-power quad-core Intel Atom processor. We then assess how quickly ADAPT’s localization improves as it observes more events and show that a partner instrument can slew to a burst’s location faster if it exploits progressive location estimates than if it waits for one final estimate. Real-time, on-board source localization thus has a role to play in cooperative observation of gamma-ray transients even when data collection time, rather than computing time, dominates the cost of detection.