– Cadence Workshop – Conclusions, Report, Recommendations and Plans Knut Olsen and Steve Ridgway August 15, 2014

Sponsoring organizations: NOAO and LSST The Organizing committee: Richard Dubois (SLAC) Eric Gawiser (Rutgers) Zeljko Ivezic (U. Washington) Ashish Mahabal (CalTech) Knut Olsen - Chair (NOAO) Steve Ridgway (NOAO) Michael Strauss (Princeton) Beth Willman (Haverford)

What did we set out to do? Get quantitative input (metrics) on how a given LSST schedule performs for specific science cases First step towards optimizing the ultimate LSST cadence Get ideas for further cadence strategy exploration, constrained by boundary conditions of hardware and key science cases

How did we organize it? Metrics Analysis Framework tutorial Plenary session to give background and set rough boundary conditions Breakouts: Transients and variables, static science, mini-surveys, and main survey optimization Plenary sessions on breakout reports, Deep Drilling, and workshop wrap-up and future plans

Breakout group deliverables A list of science cases for which the groups would like to provide metrics For those science cases, a list of variables that would enter into their metrics A translation of those variables into the output columns delivered by OpSim Performance metrics in rough analytical (or pseudocode) form A list of assumptions made in constructing the performance metrics Identification of e.g. modeling work needed in order to construct a metric that can be calibrated to provide absolute performance for a given science case A brief oral report of the breakout group discussion A brief written report (few paragraphs) for the workshop report Coded performance metrics in Python and MAF Input for main survey optimization, mini-surveys, deep drilling, commissioning We made progress on all of these deliverables

Breakout Group Leaders Mansi Kasliwal Alex Kim Michael Liu Ashish Mahabal Warren Skidmore Michael Strauss John Thorstensen Tony Tyson Kathy Vivas Lucianne Walkowicz Michael Wood- Vasey Hu Zhan

Select Highpoints from Static Science Breakouts Static science does care about cadence Agreement between diverse science groups: – Dithering! – Uniform depth – Calibration And some tension: – Restricted airmass vs. extended airmass range – Extra-long vs. shorter exposures

Static Science Breakouts cont. Both agreement and tensions argue for finishing work started on metrics for all science topics – Some work completed already (dithering for LSS) – Many metrics identified and discussed

Power spectrum with and without dithering From LSS group

Circular Variance of RotSkyPos from Weak Lensing Group

Select Highpoints from Transient and Variable Science Breakouts Variety of variables much larger than represented by attendees Need simulated catalogs containing contributed light curves targets in simulated images For rapid transients, importance of sampling more rapidly than strictly uniform (3-day)cadence – need for rolling cadence, mini-surveys and/or deep drilling to cover shorter time scales.

Transient and Variable Science Breakouts - continued LSST model cadence uses fewer visits than on- going programs for detection of solar system object – caution in planning Consider separating “15-second” exposures to give better time sampling (evaluate efficiency cost) Value of forced photometry on recent visits to support discovery of events

Transient and Variable Science Breakouts - continued Recommend call for proposals for deep drilling and mini-surveys Metrics will be needed which account for timing of availability of follow-up resources

Sampling Summary Using the FWHM of the Samping Window Function from the Slow Transients and Variables Group

Visit Triplets with Delta-t Less Than 3 Days from the Fast Transients and Variables Group

Uniformity of temporal sampling within a season for supernova cosmology From SN Group

Select Highpoints from Main Survey Breakout There is a strong desire to front-load some programs (e.g. deep coverage of the WFIRST and EUCLID fields). This competes with “continuous” uniformity. Simulations are needed to explore compromises that support both. The “Ten-percent for mini-survey” estimate should be re-evaluated based on science-metrics A scheduling algorithm based on an economic model with virtual money allotted to different proposals might give a different schedule.

Main Survey Breakout - continued There should be a small amount of time reserved for urgent and unpredicted follow-up (mini-TAC) Solar system cadence may not be needed away from the ecliptic Sharp airmass and latitude boundaries should be reconsidered.

Select Highpoints from Mini-Survey Breakouts There is exciting science to be done with LSST in the Bulge, Plane, and areas containing the Magellanic Clouds Existing cadence simulations and metrics good for some things (e.g. Magellanic structure at large scale) But higher cadence and number of observations needed for variability (MCs, Bulge & Plane) Crowding an issue for MCs and B&P, argues for limited set of excellent seeing observations  legacy value Light curve library proposal for commissioning time argues for using commissioning to anticipate broadly useful reference datasets

Confusion limits vs. radius from LMC center Saha et al. (2010) surface brightness profile Limits at which photometric errors due to crowding<0.1 mag for two seeing values

Plans for maintaining contact Participant list and mailing list (grow with new volunteers) Confluence page (current report is initial content, add metrics discussion, metric results) Contact persons for each topic: breakout group leaders

Metrics Followup Continuing support for MAF – Peter Yoachim and Lynne Jones Where to send metrics –check into git repository – – instructions will be in report and on workshop Resource page, or contact anybody in OpSim group Provide documentation of algorithm so motivation and logic is clear Provide example config file that includes appropriate captions for figures

Plans for Report Outline to be circulated in ~1 week Expect contributions of 1-2 pages, figures welcome Want summary of work performed, lists of science cases with associated metrics, assumptions, work remaining to be done Indications of alternate cadence exploration

When Should We Have Next Workshop? Goal: have users experiment with alternate cadence calculations When: ~1 year from now Where: ? Pacing item: making OpSim a tool for experimentation by community Intermediate work: continue work on getting metrics coded into MAF, recommending directions for cadence exploration

What worked well? Time between sessions; relaxed pace Availability of broad array of Project people Enthusiastic and engaged group Good preparation: workshop content, meeting support

What didn’t? Conflicting parallel breakouts

Thanks The very enthusiastic and engaged participants OpSim group who devoted time and energy to making this workshop happen (especially Lynne Jones and Peter Yoachim for their work on MAF) The 23 Breakout leaders who volunteered their time and effort LSST 2014 Administrative and Technical Support