Program: GN-2018A-Q-123

The 2018A semester presents an exciting opportunity for testing Einstein's theory of general relativity in an important and unexplored regime - within the vicinity of a supermassive black hole. This is enabled because, in 2018, the Galactic center star S0-2 will undergo its closest approach to our Galaxy's central supermassive black hole (traveling at a peak absolute speed of 8,000 km/sec and changing its radial velocity by more than 6,000 km/sec over just a few months). This is the first and only star that can test relativity in the vicinity of SMBH for the foreseeable future and this event will not occur again for another 16 years. We, therefore, propose a carefully optimized series of spectroscopic measurements of S0-2 that will measure, for the first time, the effects of relativistic redshift on its orbit relative to the predictions of Newtonian gravity.