Simulations, Metrics and Merit Functions for Mini-surveys and Deep Drilling 1

Operations Simulator Schedules a number of “proposals”, each with its field list and parameters Currently operating with V3 (obsolete, known problems) In development – V4 – 1.0 release in November – solves many problems and advances sophistication of scheduling options 2

Metrics vs Figures of Merit Which is needed? For a specific and well defined science objective, a figure of merit may be possible and essential. E.G. completeness of NEO detection in North Ecliptic Spur after N years. For a broad objective, general purpose metrics may be more appropriate. E.G. period determination for variables, rise time for transients Only specialists will really understand its basis.

Mini-Surveys Accepted Deep-drilling proposals Proposed Deep Drilling Mini-moons North Ecliptic Spur Meter-size impactors South Celestial Pole Short-exposure survey Galactic Plane GW sources

Metrics for Mini-Surveys Very few metrics are specific to mini-surveys However, most metrics are applicable to mini-surveys Except for DDF, mini-survey cadences are effectively random in current simulations

Some Metrics Useful for Mini-Surveys Area Fields Metric concept Merit Function concept Metrics implementation Merit Function Implementation AGN All X NEO, PHA Galactic novae, GP Galactic SN pre-detection Exo-planet microlensing Periodogram purity Max Phase Gap (several) Period Deviation Metric Variablility Depth ZZ Ceti count ExOr High State GRB (several) Event detection Strong lens time delay SN & Cosmology Observing Strategy Whitepaper Most metrics are general purpose, not narrowly mini-survey Gold standard is merit function implementation But the bar is at metric implementation

Max Inter Night Gap and Max Phase Gap

Temporal span of observations

Compare 2 Simulations opsim8.27 – with 4 deep drilling fields

Comparison – Median visits per Field/ Design visits u g r i z y Opsim8-27 (4 DD) 56/56 80/80 184/184 160/160 Opsim4-278 (10 DD) 63/80 140/184 141/184

How Much Mini-survey Time? Accepted Deep-drilling proposals Proposed Deep Drilling Mini-moons North Ecliptic Spur Meter-size impactors South Celestial Pole Short-exposure survey Galactic Plane ++++ GW Sources ~0??% ~10% ~??% ~10% ~0??% ~16%

How Much Time is Available? “We said 90% for the main survey, and we will use 90%” “We said we would accomplish the key science and we will accomplish the key science” Under discussion in the management committees

Visits/Field (median) Baseline Simulation Current “baseline” simulation: minion_1016 Proposal Number of fields Filters Visits/Field (median) Total Visits Fraction of Time Wide-Fast-Deep 2293 All 910 2,086,630 0.85 North Ecliptic Spur 523 g,r,i,z 304 158,992 0.06 Galactic Plane 230 180 41,400 0.017 Deep Drilling (4 approved + 1) 5 23,196 115,980 0.05 South Celestial Pole 293 52,740 0.022 Full survey 2,455,742

Visits/Field (median) Baseline Simulation Current “baseline” simulation: minion_1016 Proposal Number of fields Filters Visits/Field (median) Total Visits Fraction of Time Wide-Fast-Deep 2293 All 910 (design spec) 824 2,086,630 0.85 0.77 North Ecliptic Spur 523 g,r,i,z 304 158,992 0.06 Galactic Plane 230 180 41,400 0.017 Deep Drilling (4 approved + 1) 5 23,196 115,980 0.05 South Celestial Pole 293 52,740 0.022 Full survey 2,455,742

Visits/Field (median) Baseline Simulation Current “baseline” simulation: minion_1016 Proposal Number of fields Filters Visits/Field (median) Total Visits Fraction of Time Wide-Fast-Deep 2293 All 910 (design spec) 824 2,086,630 0.85 0.77 => 0.70 (if single images) North Ecliptic Spur 523 g,r,i,z 304 158,992 0.06 Galactic Plane 230 180 41,400 0.017 Deep Drilling (4 approved + 1) 5 23,196 115,980 0.05 South Celestial Pole 293 52,740 0.022 Full survey 2,455,742 Science in the bank, or at least in escrow.

Process for Deciding on Observing Schedule Steve Kahn in 2014 Cadence Workshop report: https://project.lsst.org/meetings/ocw/sites/lsst.org.meetings.ocw/f iles/2014CadenceWorkshopReport.pdf Excerpts in next 3 slides

Process Moving Forward (in brief) “define quantitative metrics” “experiment with different cadence strategies” - “develop a global metric for the survey” “construct a scheduler that can optimize that global metric” “define a process to evolve the cadence strategy with community input over the life of the mission”

How will we arrive at a concrete plan? “The Project will formally engage the community in making such policy decisions through its Science Advisory Committee” “The Project Science Team will provide the primary internal body within the LSST Project that will evaluate the trades “ “The Telescope & Site Team .. has formal responsibility for developing and implementing …they must respond to programmatic constraints in addition to the science guidance coming from the PST”

“Do not be concerned that crucial “cadence decisions” have already been made by LSST. This is not true. We have worked some strawman examples, but there is plenty of time for further iteration” (Kahn) (Editorial warning– the above remark is now 2 years old)

Looking ahead – What is Needed? Mini-survey/DDF Proposals Mini-survey science cases (for scientists) Well defined proposals (for simulation) Fields, filters, sequences, special conditions Metrics (may exist already), and maybe Merit Functions

Simulations, Metrics and Merit Functions for Mini-surveys and Deep Drilling Steve Ridgway 2121