The radio emission from Sgr A ^ { \ast } is thought to be powered by accretion onto a supermassive black hole of \sim 4 \times 10 ^ { 6 } \leavevmode \nobreak M _ { \odot } at the Galactic Center .
At millimeter wavelengths , Very Long Baseline Interferometry ( VLBI ) observations can directly resolve the bright innermost accretion region of Sgr A ^ { \ast } .
Motivated by the addition of many sensitive , long baselines in the north-south direction , we developed a full VLBI capability at the Large Millimeter Telescope Alfonso Serrano ( LMT ) .
We successfully detected Sgr A ^ { \ast } at 3.5 mm with an array consisting of 6 Very Long Baseline Array telescopes and the LMT .
We model the source as an elliptical Gaussian brightness distribution and estimate the scattered size and orientation of the source from closure amplitude and self-calibration analysis , obtaining consistent results between methods and epochs .
We then use the known scattering kernel to determine the intrinsic two dimensional source size at 3.5 mm : ( 147 \pm 7 \leavevmode \nobreak \muas ) \times ( 120 \pm 12 \leavevmode \nobreak % \muas ) , at position angle 88 ^ { \circ } \pm 7 ^ { \circ } east of north .
Finally , we detect non-zero closure phases on some baseline triangles , but we show that these are consistent with being introduced by refractive scattering in the interstellar medium and do not require intrinsic source asymmetry to explain .