The Legacy Survey of Space and Time (LSST)

The LSST survey strategy is described in full in the technical documentation.

Science-driven design

The LSST is motivated by four science goals.

• Probing dark energy and dark matter.
• Taking an inventory of the solar system.
• Exploring the transient optical sky.
• Mapping the Milky Way.

These combined science goals require that the LSST's Baseline Strategy include four components.

• Wide Fast Deep (WFD): a 10-year survey of the southern sky in six filters (u, g, r, i, z, and y) that obtains a ~30-second exposure every ~3 days in any filter over ~18,000 square degrees.
• Deep Drilling Fields (DDF): small sky regions that are "drilled" with sequences of repeated observations in a few filters for higher temporal sampling and deeper image coadds. The Deep Drilling Field program includes 5 DDF fields.
• Target of Opportunity (ToO): observations taken for time-domain science, e.g., within the localization regions of multi-messenger events
• Mini- and Micro-Surveys: limited sky regions observed with a custom strategy to enhance one of the four main (or enable new) science goals. Whereas DDF are single pointings (aside from dithering), mini-surveys can cover more area, though still less than WFD.

Community-led optimization

The science community, led by the LSST Science Collaborations, works together with the Rubin Survey Scheduling team to optimize the LSST design and maximize science.

The Rubin Survey Scheduling team simulates LSST observations for different strategy options and provides software for the community to evaluate these options' impact on their science goals.

The Survey Cadence Optimization Committee (SCOC) has been charged with taking this community feedback and making strategy recommendations.

For example, some of the strategy options are:

• footprints (defining the boundary of the 'low-dust extragalactic' region)
• exposure times (1x30 sec, 2x15 sec "snaps", or longer exposures in u-band)
• rolling cadence (obtaining higher-frequency observations in some sky areas in some years)
• filter balance (fraction of total time spent, and thus the relative depth, in each filter)

Telescope time is shared by all

Unlike other telescopes, astronomers do not propose for time or take their own data.

All of the data obtained with Rubin Observatory is part of the LSST, and is processed by Rubin staff and made available to all Rubin data rights holders.

Learn more about accessing the LSST data products, pipelines, and services.

Key numbers

A quick reference for the telescope, site, camera, and survey.

Go to the key numbers page.

Survey strategy documentation

Find all the details about the LSST strategy, the software for evaluating survey strategy simulations, and reports from the Survey Cadence and Optimization Committee in the technical documentation at survey-strategy.lsst.io.

Questions?

Questions about the LSST are welcome in the Support and Survey Strategy categories of the Rubin Community Forum.