Transient Gamma-Ray Observations with the HAWC Observatory

Gamma-ray bursts (GRBs), gravitational waves, neutrino events, and other transient phenomena are prime targets for multi-wavelength and multi-messenger follow ups within the community but sometimes are not feasible for instruments with limited response times and small fields of view. The High-Altitude Water Cherenkov (HAWC) Observatory, which observes 2/3rds of the sky daily with near-continuous uptime, detecting gamma rays with energies of 300 GeV to over 100 TeV, is ideal for making meaningful contributions to the study of gamma-ray transients. The HAWC Observatory can immediately begin analysis of a transient source in its field of view (~2 sr) for both external and self triggers. Additionally, with eight years of archival data, HAWC performs offline analyses of transients such as GRBs, AGN, Primordial Black Holes, and Fast Radio Bursts. We present here HAWC’s transient framework, including results from such searches including our follow-up of the extraordinary GRB221009A, discuss the recent improvements to the HAWC reconstruction and how it impacts our transient analyses, and highlight future work on transients.