Mapping Ultracool Atmospheres: Time-domain Observations of Brown Dwarfs and Exoplanets

Ultracool atmospheres (brown dwarfs, directly imaged exoplanets, close-in and transiting gas giants) are at one of the forefronts of modern astrophysics. We describe the key challenges to understanding ultracool atmospheres and the importance of time-domain observations (indirect spatial information) to address these challenges.