Public SCOC meeting minutes

(note: earlier meeting minutes were collected in this post)


The SCOC met on Friday 10/28 to finalize the preparation ahead of 11/2-3 workshop and discuss the four simulations that were released to the public on 10/25.
We discussed which elements of our recommendation should be seen as final and which are still expected to be refined and identified a need for clarity about how much space there is to refine each piece of the recommendation, to help focus community efforts.
We agreed to move into 2023 with a few simulations, instead of just one, which may be small variations on the present four. We discussed the role of each simulation in the suite of four that was released and which ones are candidate surveys vs which are instead illustrative modifications to stress the parameter space of possible choices and identified the need to be clear on this point during the presentation of the simulations at the 11/2-3 workshop. In the past week the SCOC has reviewed drafts of a report describing our simulations asynchronously. The structure of the report was discussed.

The SCOC met on Monday 11/7 to discuss and review the feedback collected through the SCOC third workshop (11/2-3) and plan the details of the release of simulations and reports through 2022, ahead of the upcoming SCOC members’ rotation. Looking at the best strategy to deliver our recommendation to the next SCOC and to the public, the SCOC decided to 1) explore a few variations of the current simulations before we identify the one that best incarnates our recommendations: this include decoupling some properties of the roll_early simulations to see the separate effects of early rolling revisit cadence, correcting the Twilight NEO current implementation to align it to the recommendations of the SCOC, and some other tweaks on filters and footprint. These simulations should become available to the SCOC in the next 2-3 weeks. 2) Reconfirmed our intention to release our recommendations in the form of a report in December 2022, explicitly isolating the elements of the recommendations yet to be made, and those that still need finalizing, into a separate section for clarity.

The SCOC has scheduled meetings for the next two mondays

The SCOC met on 11/14. We discussed the draft report that is reviewed by all SCOC members and converged on changes to the introduction. Sections describing individual recommendations are still under review. The SCOC discussed new simulations that correct some implementations that were inconsistent with the SCOC recommendations in the set of four v2.99 simulations released before the November workshop: this includes correcting the implementation of the Twilight microsurvey and starting rolling after Y1. The new simulations also implement filter swapping differently as suggested by the DESC to increase the availability of the z filter (swapping u/z/y instead of only u/y). We decided to stop simulating strength 0.5 rolling, as the recommendation is for rolling at strength 0.9. We identified the need to investigate what in the new simulations suppressed the number of observations falling in time gaps 1-14 hours and 14 hour-1 day, which were identified as important time scales for several time-domain metrics. Additional simulations were commissioned to understand what parameter changes caused these drop in observation numbers.

The next meeting of the SCOC will be 11/21

The SCOC met on 11/21 and discussed the set of v2.99 simulations and isolated two simulations that implement the recommendations of the SCOC including:

  • Implement a correct version of the twilight survey (the 4 v2.99 simulations initially released were implementing the twilight survey inconsistently with the SCOC recommendation)

  • Are compliant with SRD (with a sufficiently high number of observations in the WFD),

  • Implements rolling at 2strips, 90% but

  • Rolling only starts after Y1 (~near Y1.5),

  • Implements suppress-repeat and triplets only once every several nights to enable coverage of short time scales (<=1 day).

We currently have 2 simulations that are compliant with this scheme. In addition one of the two new simulations implement filter swaps to increase access to the z band filter which has advantates for SN Ia cosmology at high redshift (as suggested by the community in the November â…” workshop) but the impact on the time gaps between observations propagate to all filters (not just z, y, and u) so this new implementation has space for further exploration.

The SCOC will decide in a mail-in ballot if one of these two simulations should be tagged as the new baseline and if so, in a separate vote the SCOC will choose which of the two.

The SCOC still intends to continue to explore possible variations and has commissioned additional simulations to the opsim team including additional studies of the filter swapping scheme simulations that modify the fraction of time spent on special programs.

The committee will meet again on 12/1/2022