G. Witzel

AN IMPROVED DISTANCE AND MASS ESTIMATE FOR SGR A* FROM A MULTISTAR ORBIT ANALYSIS

We present new, more precise measurements of the mass and distance of our Galaxys central supermassive black hole, Sgr A*. These results stem from a new analysis that more than doubles the time baseline for astrometry of faint stars orbiting Sgr A*, combining two decades of speckle imaging and adaptive optics data. Specifically, we improve our analysis of the speckle images by using information about a stars orbit from the deep adaptive optics data (2005 - 2013) to inform the search for the star in the speckle years (1995 - 2005). When this new analysis technique is combined with the first complete re-reduction of Keck Galactic Center speckle images using speckle holography, we are able to track the short-period star S0-38 (K-band magnitude = 17, orbital period = 19 years) through the speckle years. We use the kinematic measurements from speckle holography and adaptive optics to estimate the orbits of S0-38 and S0-2 and thereby improve our constraints of the mass (

SOURCE-INTRINSIC NEAR-INFRARED PROPERTIES OF SGR A*: TOTAL INTENSITY MEASUREMENTS

M_{bh}

Simultaneous NIR/sub-mm observation of flare emission from Sagittarius A*

) and distance (

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic Center

R_o

Detection of Galactic Center source G2 at 3.8 μm during periapse passage

) of Sgr A*:

Modeling mm- to X-ray flare emission from Sagittarius A*

M_{bh} = 4.02\pm0.16\pm0.04\times10^6~M_{\odot}

Millimeter to X-ray flares from Sagittarius A*

and

A 600 Minute Near-Infrared Light Curve of Sagittarius A*

7.86\pm0.14\pm0.04

The instrumental polarization of the Nasmyth focus polarimetric differential imager NAOS/CONICA (NACO) at the VLT - Implications for time-resolved polarimetric measurements of Sgr A*

kpc. The uncertainties in

Comet-shaped sources at the Galactic center - Evidence of a wind from the central 0.2 pc

M_{bh}