Sgr A* 1.3mm VLBI observations with the EHT in 2013

We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A*, at 1.3mm (230GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional uv coverage in the N-S direction, and leads to a spatial resolution of ~30 {mu}as (~3 Schwarzschild radii) for Sgr A*. The source is detected even at the longest baselines with visibility amplitudes of ~4%-13% of the total flux density. We argue that such flux densities …