Early fast radio burst science with the Deep Synoptic Array

The 110-antenna Deep Synoptic Array (DSA), at the Owens Valley Radio Observatory, is a radio telescope purpose-built for the discovery and arcsecond localization of fast radio bursts (FRBs). FRBs are radio impulses of largely unknown origin observed at extragalactic distances. Observed FRBs encode signatures of the contents and physical conditions of baryons along their lines of sight. FRBs with well-characterized sightlines, enabled by arcsecond localization, thus provide powerful insights into the astrophysics of diffuse gas around and in between galaxies. The DSA promises to be the leading instrument to trace FRBs to their host galaxies. Each 4.65-m dish is steerable in elevation, and is equipped with a revolutionary uncooled receiver operating between 1.28-1.53 GHz, delivering a system temperature of 25 K. FRB detection is realized by the coherent combination of 95 antennas in a compact, Tee-shaped core. Detections are made in real time with a dedicated cluster of 24 servers, operating a custom pipeline that includes full interferometric cross-correlation, the formation of coherent beams for FRB searching, adaptive rejection of radio-frequency interference, and FRB-search algorithms. Upon detection, raw voltage data are saved for all antennas in the core, and 15 outrigger antennas spread over a 2.5-km area. Although the DSA will enter full operations in late 2022, commissioning observations with a 63-antenna deployment are already yielding FRB discoveries. We will present a comprehensive overview of commissioning results, including a first look at the growing DSA sample of FRBs and their host galaxies.