(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system designed
to obtain multiple images covering the sky visible from Cerro Pach\'{o}n in
northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary
mirror, a 9.6 deg2 field of view, and a 3.2 Gigapixel camera. This system
can image about 10,000 square degrees of sky in three clear nights using pairs
of 15-second exposures twice per night, with typical 5σ depth for point
sources of r∼24.5 (AB). The project is in the construction phase and will
begin regular survey operations by 2022. The survey area will be contained
within 30,000 deg2 with δ<+34.5∘, and will be imaged multiple
times in six bands, ugrizy, covering the wavelength range 320--1050 nm. About
90\% of the observing time will be devoted to a deep-wide-fast survey mode
which will uniformly observe a 18,000 deg2 region about 800 times (summed
over all six bands) during the anticipated 10 years of operations, and yield a
coadded map to r∼27.5. The remaining 10\% of the observing time will be
allocated to projects such as a Very Deep and Fast time domain survey. The goal
is to make LSST data products, including a relational database of about 32
trillion observations of 40 billion objects, available to the public and
scientists around the world