I work on a wide variety of topics in cosmology and extragalactic astronomy.  Much of my work concerns precision cosmological constraints from the measurement of the large-scale structure of the Universe.  Another major theme is the evolution of galaxies and their relation to their environment.  My work spans observations, theoretical astrophysics, and numerical simulations.

Currently I am the Director of the Sloan Digital Sky Survey III, which includes a major large-scale structure known as the Baryon Oscillation Spectroscopic Survey, as well as surveys of the stellar population of the Milky Way galaxy and a search for extra-solar planets.  My group at Harvard has data rights in SDSS-III.

Harvard-Smithsonian is a partner in the MMT and Magellan Telescopes, both of which I have used extensively for my research.

In addition to the major topics above, I have also worked in gravitational lensing, surveys and analysis of white dwarf stars, and numerous collaborative projects.

The Sloan 2.5-m Telescope at Apache Point Observatory