SCOC Phase 1 recommendations

The SCOC Phase 1 recommendations have been in progress and many of you will have seen them in draft form – but I am happy to announce that the Phase 1 Recommendations are now final! The official SCOC Phase 1 Recommendations are available as LSST Document-38411 (publicly available as

The document was guided by significant input from the community, and we would like to express appreciation once again for the ongoing effort in the form of cadence notes, workshop attendance and feedback, and contribution of metrics or metric analysis. The Phase 1 report will serve as a roadmap for the concluding round of survey cadence simulations, which include the V2.0 simulations (Survey Simulations v2.0 release (Nov 2021)) and an upcoming set of V2.1 simulations which will focus primarily on improving Deep Drilling Field options. These simulations will inform the phase 2 survey strategy recommendation which will define the baseline strategy for starting the Rubin Observatory’s Legacy Survey
of Space and Time (LSST).

Very well written and considered report, thank you to SCOC and @ljones and @yoachim for this work !

Important point to bear in mind on the micro-surveys and particularly the ToO follow-up to identify optical counterparts of gravitational wave sources. I’m personally supportive (of course!). This would only run during O5 - the fifth observing run of LIGO-Virgo-Kagra, so is time limited. There’s no case for time allocation outside the time window (yet), since there will be no triggers with skymaps of 10-100s square degrees. We will almost certainly miss O4 which will start Dec 2022 for ~1 yr, barring any major unforeseen LVK delays.

Current projections for O5 are to start end of 2025 for 1 to 1.5 yrs. So if you are running simulations for GW ToO micro-survey, it may be worthwhile to consider this time constraint in the sims, since it is a concrete requirement. The other micro-surveys are typically not time constrained in the same way. See our ApJ submission on this time critical issue Igor Andreoni et al. [2111.01945] Target of Opportunity Observations of Gravitational Wave Events with Vera C. Rubin Observatory

No clear decision by LVK what will happen after O5, and will need to review the results from O5 before projecting the Rubin response in future O6+ runs. So in the first instance, I think SCOC and simulations can focus on this very specific time interval in 2025 - 2026.

This is great further clarification on the GW ToO micro survey - we don’t currently include this time constraint about when it operates, but just use about 1% of the total survey. We should further coordinate the plan for GW ToOs so we can simulate this more accurately.

One nice thing about this being constrained to 2025-2026 (and potentially onwards) is that this should be after the first year of operations. The baseline survey strategy for Rubin that will released by the SCOC at the end of 2022 obviously defines a strategy for the entire ten years – but it is primarily intended to be a working plan for the first year of the survey. Based on a deeper understanding of how the telescope is functioning, as well as potentially changing science priorities, the plan will be re-evaluated at least annually. Most (although not all) of the micro surveys do not need observations during the first year specifically, so there will be some additional time to develop a specific plan for these, a plan that can be informed by more information about the on-sky performance.

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