The role of computation in astrophysics has grown substantially over the last decade, driven by the growth in computer power, sophistication of computational methodologies, and increasing data volumes. Over the next decade, the importance of computational astrophysics will continue to grow as computers reach exascale performance and data-intense observational surveys like the Large Synoptic Survey Telescope, Euclid, and WFIRST become available.

Weak gravitational lensing is a unique technique to map the distribution of dark matter in the universe. It is also a sensitive probe of dark energy, large scale structures in the universe, and cosmological parameters. We will first briefly describe the principles of weak lensing. We will then review the current observational status of this field, highlighting several new measurements especially from the ongoing Dark Energy Survey (DES).

Abstract: Adaptive optics (AO) imaging and spectroscopy of the central star cluster in the Galactic Center over the past three decades have established that there is a concentration of 4 million solar masses associated with the compact radio source SgrA*, presumably a massive black hole.