1. Simulations, Metrics and Merit Functions for Mini-surveys and Deep Drilling1

2. 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

3. 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.

4. 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

5. 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

6. 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

7. Max Inter Night Gap and Max Phase Gap

8. Temporal span of observations

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

10. Comparison – Median visits per Field/ Design visitsu 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

11. 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%

12. 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

13. 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

14. 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

15. 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.

16. Process for Deciding on Observing Schedule
Steve Kahn in 2014 Cadence Workshop report:
iles/2014CadenceWorkshopReport.pdf
Excerpts in next 3 slides

17. 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”

18. 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”

19. “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)

20. 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

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