The death of massive stars, manifested as gamma-ray bursts and core-collapse supernovae, critically influence how the universe formed and evolves.Despite their fundamental importance, our understanding of these enigmatic objects is severely limited.We have performed a concept study of an Astrophysical Transient Observatory (ATO) that will rapidly facilitate an expansion of our understanding of these objects.ATO combines a very wide-field X-ray telescope, a near-infrared telescope, a multi-mode ultraviolet instrument, and a rapidly slewing spacecraft ultra max dog shampoo to realize two primary goals: (1) characterize the highest-redshift massive stars and their environments, and (2) constrain the poorly understood explosion mechanism of massive stars.The goals are met by observing the first massive stars to explode as gamma-ray bursts and to probe their environments, and by observing the shock breakout of core-collapse supernovae to measure the outer envelope parameters of massive stars.
Additionally, ATO will observe the shock breakout of Type Ia supernovae and their shock interaction trufit wrist brace with a companion, electromagnetic counterparts to gravitational wave sources, kilonovae, tidal disruption events, cataclysmic variables, X-ray transients, flares from exoplanet host stars, and the escape of ionizing radiation from star-forming galaxies.A description of the ATO instruments, the mission simulation, and technology readiness level is provided.