The Athena X-ray Observatory: observing luminous extragalactic transients

The ESA Athena X-ray observatory will combine exceptionally high throughout with high spectral-energy resolution. Athena will revolutionize many aspects of high-energy astrophysics. Here we concentrate on the subject of time-domain astronomy. Many of the most powerful transient sources, including gamma-ray bursts and tidal disruptions events, are bright X-ray sources. Athena will be designed to have a fast-response capability, permitting efficient observations of many transients. We will summarize the proposed capability of the mission and illustrate science programs to study transients ranging from the most distant GRBs to nuclear activity in nearby galaxies.