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

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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

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

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.

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

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)

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!

M1M3 Cell Post Stress Relieving CAIG

Telescope Mount Assembly (TMA) Asturfeito

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

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