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The Survey Cadence Optimization Information

Draft Phase 1 SCOC recommendation

Executive summary for Draft Phase 1 SCOC recommendation

LSST Cadence Notes Solicitation (Dec 2020), Responses received

The First SCOC-Science Collaborations Workshop

The Second SCOC-Science Collaborations Workshop

August 2020 Project report about Survey Strategy and Cadence Choices

Survey Cadence Optimization Committee’s Timeline for choosing the initial LSST surveying strategy

Updated Timeline (from October 2021)

Discussions about the survey strategy at

The Purpose of the SCOC

The SCOC is advisory to the Rubin Observatory Operations Director (currently Bob Blum). It will begin its work in 2020, and will be a standing committee throughout the life of Rubin Observatory operations. 

Its tasks are as follows:

  • Based on input from the OpSim team and the Vera C. Rubin Observatory Legacy Survery of Space and Time (LSST) Science Collaborations, make specific recommendations for the cadence choices for the full 10-year survey. These recommendations will include a description of the pros and cons of the various choices, and will be in the form of one or more reports which will be made public.
  • Help communicate these recommendations to the science community through, for example, posts on and reports to the LSST Science Collaborations.
  • Based on the plans for commissioning, and the realized performance of the telescope and software, make specific recommendations for “Early Science” observations, to be carried out at the end of commissioning and the first months of Rubin Observatory operations.
  • During operations, receive reports from the Survey Evaluation Working Group (SEWG), a project-internal group of scientists that will evaluate the current and expected performance of the survey and scheduler. Use this information, together with an understanding of the science outputs and changing scientific landscape of the Rubin Observatory, to make recommendations for changes in survey strategy, including Target of Opportunity observations and the use of Director’s Discretionary Time.

Membership of the SCOC

The SCOC will consist of roughly 10 individuals, named by the Rubin Observatory LSST Science Advisory Committee (SAC) and drawn almost entirely from the science community (i.e., from people not paid by the Rubin Observatory Project). It will be chaired, however, by the Rubin Observatory LSST Head of Science (currently Zeljko Ivezic), who will be a non-voting member.

While the existing LSST Science Collaborations will be a source of members of the SCOC, individuals will not represent the specific scientific interests of the LSST Science Collaborations they happen to be members of, but (like the SAC) will work to optimize the global scientific productivity of the Rubin Observatory LSST.

The SCOC will be mostly comprised of scientists from both the US and Chile, and should include at least one individual from Chile.

The SCOC will need expertise in the various areas which pull the cadence decisions in specific directions; a partial list follows:

  • Solar System (including both inner and outer solar system)
  • Low-latitude Milky Way science/crowded fields
  • High-latitude Milky Way science, and resolved stars in nearby galaxies
  • Variable stars and Milky Way transients
  • Extragalactic transients
  • Galaxies and strong lensing
  • AGN
  • Weak Lensing Cosmology
  • Supernova Cosmology
  • Footprint and sky coverage with external surveys
  • Data Management

To broaden the expertise of the SCOC itself, it will actively seek input and advice from members of the scientific community and the LSST Science Collaborations. The SCOC members will be free to share information presented in the SCOC discussions with the experts with whom it consults.

Membership on this committee will initially be for two years, with possibility of renewal.

SCOC decision-making process

The SCOC will start its deliberations in summer 2020. It will meet by default once a month via telecon through the first year or so of operations; we anticipate that the rate of meetings can slow down after that. Occasional face-to-face meetings will likely be necessary, especially as major decision points are reached. The SCOC Chair will schedule the meetings. The Project would provide logistical and financial support for those meetings (including travel costs for all participants). The Project will also endeavor to provide occasional travel support for SCOC members to travel to scientific conferences to gain insight into some of the issues that the SCOC is exploring.

As mentioned above, the SCOC will reach out to the scientific community and the LSST Science Collaborations when expertise is needed in specific areas. An open process of communication with members of LSST Science Collaborations will lead to better understanding of, and community buy-in to, the SCOC recommendations.

The SCOC chair will be responsible for informing, and where appropriate consulting with, all relevant operations partners, including the US governmental funding agencies.

The SCOC would operate by consensus to the extent possible. But formal votes would be taken at major decision points:

  • Development of an initial 10-year survey strategy plan, and drafting the report describing that plan.
  • Development of an “Early Science” plan
  • Recommendations of significant changes in survey strategy during operations.

The results of these votes will be recorded in the SCOC minutes.

The minutes of the SCOC, and the reports it writes to the Operations Director, will be made public, and will be posted on and other websites as appropriate.

Relationship to other committees

The Science Advisory Committee (SAC) is responsible for drafting the SCOC charge (i.e., this document), and identifying members to serve on the SCOC.

The Survey Evaluation Working Group (SEWG) includes representatives from Observatory Operations and Data Production (i.e., it mostly consists of individuals within the Project). On a quarterly basis, it evaluates the current and expected performance of the scheduler, and presents its findings both to the Operations Director and to the SCOC.

Committee Members:

 Franz Bauer, Universidad Católica, Chile
 Sarah Brough, University of New South Wales 
 Renee Hlozek, University of Toronto
 Mansi Kasliwal, Caltech 
 Knut Olsen, NSF’s NOIRLab 
 Hiranya Peiris, University College London
 Meg Schwamb, Queen's University Belfast
 Dan Scolnic, Duke University
 Colin Slater, University of Washington  
 Jay Strader, Michigan State University

Non-voting Committee Members:

 Lynne Jones, Rubin Observatory, ex officio
 Željko Ivezić, Rubin Observatory, Chair

Financial support for Rubin Observatory comes from the National Science Foundation (NSF) through Cooperative Agreement No. 1258333, the Department of Energy (DOE) Office of Science under Contract No. DE-AC02-76SF00515, and private funding raised by the LSST Corporation. The NSF-funded Rubin Observatory Project Office for construction was established as an operating center under management of the Association of Universities for Research in Astronomy (AURA).  The DOE-funded effort to build the Rubin Observatory LSST Camera (LSSTCam) is managed by the SLAC National Accelerator Laboratory (SLAC).
The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 to promote the progress of science. NSF supports basic research and people to create knowledge that transforms the future.
NSF and DOE will continue to support Rubin Observatory in its Operations phase. They will also provide support for scientific research with LSST data.   

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