Kepler-503b: An Object at the Hydrogen Burning Mass Limit Orbiting a Subgiant Star

NSF [AST 1517592, 1616684, 1616636]; Spanish Ministry of Economy and Competitiveness (MINECO) [AYA-2017-88254-P]; NASA [NAS5-26555]; NASA Office of Space Science [NNX09AF08G]; NASA; NSF; NASA Science Mission directorate; Alfred P. Sloan Foundation; U.S. Department of Energy Office of Science; University of Utah; Brazilian Participation Group; Carnegie Institution for Science; Carnegie Mellon University; Chilean Participation Group; French Participation Group; Harvard-Smithsonian Center for Astrophysics; Instituto de Astroffsica de Canarias; Johns Hopkins University; Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo; Lawrence Berkeley National Laboratory; Leibniz Institut fur Astrophysik Potsdam (AIP); Max-Planck-Institut fur Astronomic (MPIA Heidelberg); Max-Planck-Institut fur Astrophysik (MPA Garching); Max-Planck-Institut fur Extraterrestrische Physik (MPE); National Astronomical Observatories of China; New Mexico State University; New York University; University of Notre Dame; Observatario Nacional/MCTI; Ohio State University; Pennsylvania State University; Shanghai Astronomical Observatory; United Kingdom Participation Group; Universidad Nacional Autonoma de Mexico; University of Arizona; University of Colorado Boulder; University of Oxford; University of Portsmouth; University of Virginia; University of Washington; University of Wisconsin; Vanderbilt University; Yale University