I'm a researcher in astrophysics and cosmology in the physics and astronomy department at the University of California, Riverside, working particularly with the FIELDS program. I'm also a visiting scientist at NASA JPL and at IPAC.

My research focuses on doing cosmology with large-scale surveys. My main focus is weak lensing, particularly weak lensing with galaxy clusters. I'm a member of the Large Synoptic Survey Telescope Dark Energy Science Collaboration and the WFIRST science investigation team led by Dr. Olivier Doré. I'm also an external collaborator for the the Hyper SuprimeCam Subaru Survey Program (weak lensing working group) and Dark Energy Survey (clusters working group), and I've made extensive use of SDSS data.

I've made measurements of the masses of X-ray clusters (from the RBC catalogue) and optical clusters (MaxBCG and redMaPPer) using SDSS sources. The X-ray work used hydrodynamic simulations directly as a source for lens models, and the redMaPPer work involved careful modeling to try to mitigate or marginalize over systematic effects. Some smaller projects have projected the impact of systematic biases and uncertainties in upcoming weak lensing measurements. Specific papers can be found on the publications page.

Part of my work involves characterization and mitigation of sources of systematic error as well as catalog validation work. I was a member of the executive committee of the Great3 challenge, and I've been leading a systematics software package called Stile that we're using in HSC. I write open-source software in addition to Stile; there are highlights on the software page. I'm also interested in using big data techniques in astronomy and cosmology.