The nature of Dark Energy is one of the greatest mysteries in science today. It was discovered in 1998, when scientists found that the expansion of the universe is accelerating. We call the force driving this expansion Dark Energy, but beyond that we know very little. LSST will produce a unique dataset of billions of galaxies, which will allow us to measure how Dark Energy behaves over time with unprecedented precision. The LSST dataset will also enable us to tackle several other questions in cosmology and fundamental physics.

The LSST Dark Energy Science Collaboration will prepare for and carry out a variety of cosmological analyses with the LSST survey. In advance of LSST's first observations, DESC will help prepare for LSST science analysis, make synergistic connections with ongoing cosmological surveys and provide the dark energy community with state of the art analysis tools. 

This web site gives an introduction to the Working Groups of LSST DESC, and provides points of contact for people who want to find out more. The Featured Projects are a set of products that we expect will be useful to the community and have been released periodically. More information on the structure of the DESC can be found in the Governance Document. The Collaboration has laid out the main science activities that we need to undertake to be ready for LSST first light in its Science Roadmap (SRM, last updated to v1.4 in January 2019). The SRM follows on from the 2012 DESC white paper

Members of the wider research community are invited to join the LSST DESC, according to the membership policies described in the white paper. If you're interested in joining the Collaboration, please see the information on applying for DESC Membership. The application is simple, you just need to provide a short statement of the work you wish to pursue that is relevant to the DESC. This will give you access to the LSST DESC collaboration web pages, so that you can learn more about relevant DESC activities to assist in writing a proposal for Full Membership.

The LSST DESC carries out its software development on GitHub.  For a list of our public software repositories, see https://github.com/LSSTDESC

LSST DESC institutional acknowledgments:

The DESC acknowledges ongoing support from the Institut National de Physique Nucl\'eaire et de Physique des Particules in France; the Science \& Technology Facilities Council in the United Kingdom; and the Department of Energy, the National Science Foundation, and the LSST Corporation in the United States.  DESC uses resources of the IN2P3 Computing Center (CC-IN2P3--Lyon/Villeurbanne - France) funded by the Centre National de la Recherche Scientifique; the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S.\ Department of Energy under Contract No.\ DE-AC02-05CH11231; STFC DiRAC HPC Facilities, funded by UK BIS National E-infrastructure capital grants; and the UK particle physics grid, supported by the GridPP Collaboration.  This work was performed in part under DOE Contract DE-AC02-76SF00515.