1. Systems Engineering, Verification, and Commissioning for LSST George Z
Systems Engineering, Verification, and Commissioning for LSST George Z. Angeli Chuck Claver, Bo Xin, Brian Selvy LSST Project Systems Engineering June 23, 2016

2. LSST Systems Engineering
Managing technical complexity
System decomposition
Requirements flow-down and management
Performance allocations and margins
Interface definition and control
System integration
System verification and validation
Managing technical progress – “keep an eye on the big picture”
Configuration control – change control
Technical assessment – reviews
Decision analysis – trade studies
Technical data management – databases (DocuShare, confluence, github)
Communications

3. Recent Trade Studies Evaluating change/waiver requests
Telescope Mount Assembly structural damping
WFS intra/extra focal offset and midpoint position from science sensors
Evaluating as-built features (verification by analysis)
M1M3 performance, including crows’ feet
Evaluating architectural decisions
WFS algorithm testing
AOS control strategy and law – early error budget compliance assessment
M1M3 dynamic control during slew
Trade studies
M1M3 actuator force accuracy requirement
Impact of sensor height variation on ellipticity
Analysis of dome seeing
AOS compensation for non-actuated perturbations

4. Active Optics System Update
Residual after Look-Up Table Correction
Mirror Figures and Rigid Body Positions
Controller
Wavefront Error
PhoSim Model
Telescope
Image Quality
(PSSN & ellipticity)
Camera Internal Optics
Wavefront Sensor
Wavefront Sensor Feedback
Estimator
Atmosphere
In PhoSim
Temperature, Elevation, Camera Rotation, Thermal Gradients,
Laser Tracker accuracy
Performance metrics include
Effective FWHM (size of Gaussian equivalent PSF)
PSSN (Δm5)
ellipticity
Includes sensor height variation driving instrumental ellipticity
AOS performance
(FWHMeff and ellipticity)
Sensor height probability distributions
31 field points

5. M1M3 Surface Quality Crows’ feet (mostly) on M3
Image Quality (PSSN)
Crows’ feet (mostly) on M3
Polishing features due to small bubbles
Effects on
Image Quality
Ellipticity
Background
Interferometer cannot resolve
Synthetic map generated by adding local measurements
Image depth loss can be compensated by ~2.5% longer exposure
No noticeable effect on ellipticity
Ellipticity

6. M1M3 Surface Quality Scattered light and diffraction analyses show:
Background surface brightness increases around point sources at radii ~40 arcsec to 1 arcmin (<2 mag/arcsec2)
Area loss (to shallower limit) around stars brighter than 10 mag is ~0.8% of total area
aureole
Purple crosses for reference only

7. Telescope Slew Time
Open shutter efficiency critically depends on slew time – expected 77%:
Mitigate structural excitation due to large forces by
Increased damping
Minimum jerk repointing command
Vendor requested to remove tuned-mass dampers to maintain high resonant frequencies
Command torque
Trade study to evaluate optical jitter, using
Full FEA dynamics
Optical sensitivity
Further optimized command leads to satisfactory jitter
Optical Line-of-Sight
Control torque

8. Requirements Validation
System requirements validation
Did we specify the right system?
Assuming the system meets its requirements, can we do the envisioned science with it?
Requirements flow down (subsystem requirements validation)
Did we specify the right subsystems?
Assuming each subsystem meets its requirements, will the entire system meet the top level requirements?
History by now:
Demonstrated at FDR

9. System Verification against Requirements
Subsystem design and construction verification
Did we design and build the subsystems right?
Do the subsystems meet their requirements?
System design and construction verification
Did we design and integrate the system right?
Does the system meet its requirements?
Inspection, demonstration, analysis, test during
Subsystem Integration and Test
System Commissioning

10. Verification Matrix: Observatory System Specification
Verif. Method
Prim
Sec
Total
% Total
Test
100 20
120
25.3%
Demonstration 92 28
Analysis 74 93
167
35.2%
Inspection 47 67
14.1%
313
161
474
100%
Being updated for the NSF/DOE Status Review in August, 2016

11. Verification Documents
Detailed updates for:
Camera I&T Review
Telescope & Site I&T Review
Data Management I&T Review
LSST Commissioning Review

12. Phase III of Commissioning
System Validation
Science validation
Did we build the right system?
Can the observatory deliver the science expected?
Demonstrate that LSST is capable of providing the science it is meant to
Full validation requires full survey (10 years of operations)
Science Commissioning (2nd year of Commissioning)
Verify single visit SRD requirements
Verify full survey SRD image stacking performance (depth and PSF shape) using limited number of objects
Verify full survey SRD area coverage by time-proportional area coverage
Demonstrate that LSST is ready for self-directed operations through an autonomous mini-survey (30 days)
Phase III of Commissioning

13. LSST Commissioning LSST Commissioning comprises
Assembly, Integration, and Verification (AIV)
Assembly of the observatory on the summit
Integration of observatory functionalities into a working system
Verification of its performance against the requirements
Commissioning
Establishing final observatory performance, operational procedures, and as-built documentation
Validating the observatory against its scientific purpose
LSST Commissioning phases
Early Integration and Test – with the Commissioning Camera (ComCam)
Full Integration and Test
Integration of Telescope, Camera, and Data Management
Verification of technical performance
Science Verification and Validation
Characterization of the observatory with
respect to expected survey performance (science requirements)
Starts with acceptance of Telescope
(December 2019)
Concludes with Operations Readiness Review
(August 2022)

14. Early System Integration and Test (with ComCam)
A single raft camera operating as a surrogate for the full science camera.
Corrector for ~40 arcmin FOV
6 Filters (u-g-r-i-z-y planned)
Interface testing – utilizes as many Camera interfaces as possible:
CCS-OCS – communications and control
SDS-DM – data transfer
WDS-TCS – wavefront sensing
GDS-TCS – guiding
Guider, WFS, and AOS initial verification
Calibration Operations and Calibration Data Products Pipeline Processing
Scheduler Driven Operations Testing
DM Algorithm initial testing
6 months
June 2020
December 2019

15. Full System Integration and Test (with Camera)
Installation and basic functional checkout of Telescope-Camera-DM
Calibration and verification of AOS
Verification of system requirements (Observatory System Specifications)
Verification of system interfaces
Functional tests of scheduler driven observing
DM pipeline testing with full Focal Plane Array data
August 2020
April 2021

16. Science Verification and Validation
Verification of science requirements (Science Requirements Document)
Single visit requirements
Survey requirements (limited number of fields, rate of area coverage)
Establishment of final operational procedures
Operations Readiness mini-survey using Initial Survey Cadence
Level 1 data products
Level 2 data release
Pre-Operations Engineering (mirror coating, scheduled maintenance)
August 2021
April 2021

17. The Commissioning Team
Technical team – subset of existing subsystem teams
Science team – some existing, some new hire
Core team relocates to La Serena (Chile)
Majority of the crew rotates to Chile as needed
FY19
FY20
FY21
Com. Scientists
5.3
8.7
11.3
DM Scientists
3.5
4.5
3.9
TS Scientists
2.2
2.5
2.7
Cam Scientists (DOE)
3.0
4.0
5.0
Science Team Total
14.0
19.7
22.9
Engineers
7.0
6.2
6.8
Technicians
5.2
6.0
7.6
SW Engineers
11.4
12.1
8.6
Cam Engineers (DOE)
17.0
16.0
15.0
Technical Team Total
40.6
40.3
38.0
Commissioning Total
54.4
60.0
60.9

18. Commissioning Management
Project Director and Manager maintains overall authority on all commissioning activities, budget and schedule.
Systems Engineering Manager and Systems Scientist are responsible for the commissioning effort, including planning, prioritizing, coordinating the day-to-day commissioning activities, and functional supervision of assigned staff.
Chilean Site Manager supervises logistic and administrative operations of work carried out in Chile at the Summit and Base Facilities.
LSST safety staff continues their role to ensure all activities are conducted safely; particularly for the on-site activities at the Summit Facility.
Subsystem Managers continue to provide administrative supervision to personnel assigned to the commissioning team and responsibility for remaining construction activities not associated with commissioning.

19. Commissioning Flow
Commissioning phases and major tasks will be reviewed
Technical audit of progress and compliance
Activity and verification reports
Expected documentation of the system
Safety record
Decision on progress with non-conform components and subsystems
Data will be available for LSST community
LSST community is welcome to explore data
Limited checks before “release” - no guarantees
Resources limited for support
Access to computational facilities subject to availability
Exact rules not settled yet

20. Planning for Commissioning
LSST Final Design Review (December 2013)
Commissioning Plan
Verification Matrices (initial) for observatory level requirements (SRD, LSR, OSS)
Subsystem Integration and Verification Plans
Camera I&T Review – March 2016
Telescope and Site I&T Review – expected in the fall
Data Management I&T Review – expected in the fall
Demonstrate for each subsystem
Verification Matrix in place (verification methods, owners, levels, requirements and success criteria)
Cost and schedule updates for the I&T phase
Specification of long lead time HW and SW tools ready for purchase and/or development
Observatory Commissioning Plan update
Commissioning Review (PDR level) – early next year (2017)

21. Summary Systems engineering is mature
Technical coordination of the project is ongoing and timely
Compliance and performance estimation is ongoing
Proper tool set (“framework”) is available and fits the purpose
Detailed updates to the Observatory Verification Plan are in progress
Detailed updates to the Commissioning Plan are in progress
Project is getting ready for successful Commissioning!

22. M1M3 Cell Post Stress Relieving
CAIG

23. Telescope Mount Assembly (TMA)
Asturfeito

24. Large Optical Elements of the Camera
L3 Blank
TSESO
r-Filter Blank
L2 Optic
AOS
Rayotek
Reference Sphere

25. Sensor Chips 1 accepted Science Grade and 2 candidate devices in-hand
and 3 more on the way
2 first article Wavefront Sensors received, all requirements passed