Program: GS-2019A-Q-316

We want to use Flamingos-2 on Gemini South to discover and characterize late-T and Y dwarfs in the 20 pc volume around the Sun. These objects will allow us to answer some of the open questions in astronomy: how can star formation create objects of extremely low mass? And with what efficiency? Is there a low-mass cutoff of star formation? And if so, where is it? The only data set capable of uncovering more of these objects, and therefore answer the above questions, is the set from WISE. Funded by NASA's ADAP program, CatWISE (PI Eisenhardt) will combine data from all phases of the WISE mission, to produce a catalog of ~1 billion sources with W1, W2, and proper motion measurements down to a greater depth compared to AllWISE. Crucially, CatWISE has access to the coldest, least massive members of the local sub-stellar neighborhood, a population completely undetectable by Gaia and any other existing optical and near-infrared survey. Gemini South will play a critical role in our southern hemisphere follow-up campaign, complementing proposed and scheduled observations at Palomar and Keck in the north, by providing strong constraints on the nature of our discoveries (via photometric and spectroscopic typing), thus allowing robust pre-selection of exquisite exoplanet analogs that will be prime targets for JWST.