LSST Commissioning Plan LSE-79 Latest Revision 10/5/2013
Large Synoptic Survey Telescope (LSST)
|LSST Commissioning Plan|
|Chuck Claver & Christopher Stubbs|
|Latest Revision Date: October 5, 2013|
|This LSST document has been approved as a Content-Controlled Document. Its contents are subject to configuration control and may not be changed, altered, or their provisions waived without prior approval. If this document is changed or superseded, the new document will retain the Handle designation shown above. The control is on the most recent digital document with this Handle in the LSST digital archive and not printed versions.|
Added activity sequences for DM pipeline testing and verification; added staffing tables by year-type at the commissioning activity centers.
Updated schedule and resources to PMCS baseline
Major revision to address changes in Camera delivery, addition of a Commissioning Camera and overall project schedule
|Reformat to comply with standard project document formatting.||
Additional edits by S. Wolff. Update staffing levels per PMCS-3
Updated requirements for Operation Readiness
Implementation of 10/5 revision per LCR-158
Table of Contents
Change Record i
Scope and Purpose v
Definitions of Terms vi
Reference Documents vi
|1||Commissioning time line and overview 1|
|2||Acceptance testing and commissioning preconditions 3|
|2.1||Telescope & Site 3|
|2.3||Data Management 5|
|2.4||Observatory Control System 6|
|2.5||Auxiliary Telescope 6|
|2.6||Ancillary Equipment 7|
|2.7||Software Tools and Other Capabilities 7|
|2.8||External Data Sets 8|
|3||Early System Integration & Test 9|
|3.1||Build-Refine Telescope Mount Pointing Model 10|
|3.2||Initial Guider Verification 11|
|3.3||Initial Wavefront Sensing Verification 11|
|3.4||Scheduler and Autonomous Operations Testing 12|
|3.5||Mini-Survey and DM Algorithm Testing 12|
|4||Full System Integration & Test 14|
|4.1||Camera-Telescope Integration 14|
|4.1.1||Fixtures and Handling 15|
|4.1.2||Camera-Telescope Physical Integration 15|
|4.1.3||Initial Camera-Telescope Testing 15|
|4.2||Active Optics Verification 17|
|4.2.1||Wavefront Sensor to FPA Calibration 17|
|4.2.2||Optical Reconstructor Verification 18|
|4.3||Data Management Integration 18|
|4.3.1||Networking Bandwidth Verification 19|
|4.3.2||DM-Telescope-Camera Interface Verification 19|
|4.3.3||Initial Alert Production and Calibration Pipeline Tests 20|
|4.3.4||Mid-Scale Calibration Products Pipeline Tests 20|
|4.3.5||Mid-Scale Alert Production Piepline Testing 21|
|4.3.6||Data Release Production 21|
|5||Science Verification 22|
|5.1||Single Image/Visit Performance 24|
|5.2||Full Survey Performance Verification 24|
|5.2.1||10-year Stacked Image Performance 24|
|5.2.2||!0-year Area and Temporal Coverage 25|
|5.3||Parallel Data Management Activities 25|
|5.3.1||Final Archive Center and US DAC Integration and Testing 26|
|5.3.2||Final Calibration Data Products Verification 26|
|5.3.3||Level 2 Data Release Production Verification 26|
|5.4||Other data needed during commissioning 26|
|6||Operations Readiness 28|
|6.1||Operations Readiness Mini-Survey 28|
|6.2||Operations Readiness Review 28|
|7||Pre-Operations Engineering 30|
|7.1.1||M1M3 Mirror Recoating 30|
|7.1.2||Camera Maintenance and Servicing 30|
|8||Commissioning Management and Staffing 31|
|8.1||Commissioning Oversight 32|
|8.2||Commissioning Staffing 32|
|9.1||Example Mini-Survey 34|
|The LSST Commissioning Plan|
Scope and Purpose
This document describes the LSST Commissioning Plan that carries the MREFC funded project from construction through to operations readiness. This plan includes a definition of three distinct phases of commissioning, principal objectives for each phase, key activities and tasks, and the management structure to carry out the work described. Last, the criteria by which the project will be judged as “operation ready” is provided.
1) Describes the necessary pre-conditions that each of the three subsystems, Camera, Telescope and Site, and Data Management, along with the Observatory Control system must satisfy prior to the start of the two-year commissioning period;
2) Outlines the remaining technical integration activities and tests that must be accomplished during the Early and Full System Integration and Test period;
3) Outlines the verification methods that will be used to show compliance with the survey performance detailed in the LSST SRD (document LPM-17) and the LSST System Requirements (LSE-29);
4) Describes the specific tests, measurements, and analysis that will be performed to show compliance with the SRD/LSR;
5) Defines the criteria, methods, and review process that establishes the readiness of the LSST for operations;
6) Defines the overall management structure, lines of authority, oversight, and data distribution policies that will be in place for the 2-year commissioning period; and
7) Outlines contingency plans in the event key preconditions are not met.
The principal outputs from the commissioning phase are:
1) Operational procedures and documentation for operation of the LSST observatory as a science facility, including end-to-end data management;
2) Reports documenting as-built performance of the hardware and software including: modifications, exceptions, recommendations for improvement; and
3) Test data showing characterization of and compliance with the requirements in the SRD (LPM-17), LSR (LSE-29), and OSS (LSE-30).
This plan covers the full set of activities for commissioning the LSST Observatory facilities in Chile and the partial commissioning of the Archive Facility at NCSA. It does not cover final commissioning of the annual data release processing pipelines and data products production, as these are covered under operations.
Definitions of Terms
BFP – Best fit plane
CCS – Camera Control System
ComCam – Commissioning Camera
DAC – Data Access Center
ISR – Instrument signature removal
FPA – Focal Plane Array
LSR – LSST System Requirements
M1M3 – Primary-Tertiary mirror monolith
M2 – Secondary mirror
SRD – Science Requirements Document
RVC – Reciprocating vertical conveyor
OCS – Observatory Control System
OSS – Observatory System Specifications
ORR – Operations Readiness Review
TCS – Telescope Control System
WCS – World Coordinate System
“LSST Science Requirements Document” (LPM-17)
“LSST System Requirements Document” (LSE-29)
“LSST Observatory System Specifications” (LSE-30)
“LSST Camera Requirements Document” (LSE-59)
“LSST Telescope and Site Requirements Document” (LSE-60)
“LSST Data Management Requirements Document” (LSE-61)
“LSST Verification and Validation Process” (LSE-160)
The LSST Commissioning Plan
1 Commissioning time line and overview
The commissioning phase of the project is the final stage of a comprehensive verification and validation process (see LSE-160 for details) and is defined by three phases of activity: 1) a period of telescope commissioning and system tests using a commissioning camera (Early I&T); 2) a period dominated by the technical activities of integrating the Camera and Telescope and Data management (Full System I&T); and 3) with a period that is focused on characterizing the system with respect to the survey performance specifications in the SRD/LSR (Science Verification) leading to operations readiness. It is important to understand that these three phases represent a continuum of increasing system functionality and capability and that the plan presented here is meant to be flexible to take full advantage of opportunities as they occur.
Each of the three principal subsystems – Data Management, Camera, and Telescope & Site, along with the Observatory Control System – must pass their respective acceptance tests as a necessary precondition (see Section 3) for entering the Commissioning phase. The transition from the project Construction phase to Commissioning starts with the 3-mirror telescope having demonstrated nominal on-axis image quality with the Commissioning Camera (ComCam). This “Engineering First Light” occurs approximately 4 years after the start of MREFC construction (see Figure 1). The full science Camera will be delivered to the observatory approximately 1 year later to begin the Full System Integration and Test phase. At the start of Early Integration and Test, the Data Center at the Base Facility in la Serena, Chile will be fully integrated and ready to accept and process ComCam data. The Data Management group will have delivered the commissioning computer cluster along with LSST software Release-8 (see Appendix ## for full list of R8 functionality).
The first phase of commissioning under Early Integration & Test is designed to test and verify the telescope and system interfaces using ComCam (see Sec. 4 for description). During this period the telescope active optics system will be brought into compliance with system requirements, the scheduler will be exercised and all safety checks verified for autonomous operation, and early DM algorithm testing will be performed with on-sky data from ComCam using the commissioning cluster at the Base Facility.
The second phase of activities under Full System Integration and Test is designed to complete the technical integration of the three subsystems, show full compliance with system level requirements (detailed in the Observatory System Specifications LSE-30) and ICDs, and provided additional data for further DM software and algorithm debugging. System level requirements that flow directly to subsystems without any further derivation will be tested for compliance at the subsystem level and below under the supervision on the project Systems Engineer. This document includes the general approach and goals for these tests. It is expected that roughly 4-6 months into the System I&T phase the telescope and camera will be fully integrated and producing (at least periodically) science grade images over the full FOV, at which point “System First Light” will be declared.
Figure 1: Key milestones in the LSST project assuming MREFC funding starting in mid-FY2014.
The third and final phase of activities under Science Verification is designed to show compliance with the survey performance specifications detailed in LSST System Requirements document (LSE-29) and fully characterize the range of demonstrated performance per the LSST Science Requirements document (LPM-17) . These activities are based on the measured “On-Sky” performance and informed simulations of the LSST system. The data from these activities will be released to the Science Collaborations for analysis and early scientific studies. This document discusses the general philosophy and structure of the observational verification. The detailed description of the observational programs used for science verification will be covered in the Science Verification Matrix. An Operations Readiness Review (ORR) defines the end of the Science Verification phase, where the project will present results of the commissioning effort to the NSF and panel of community representatives. The ORR will signify the end of construction and the conclusion of the MREFC project.
2 Acceptance testing and commissioning preconditions
Each of the LSST subsystems will have gone through substantial testing and are expected to be in an advanced state of readiness prior to their entry into the Commissioning Phase covered by this plan. The acceptance criteria and expected state for each of the three subsystems and the OCS required to enter the Commissioning Phase are described in the sections that follow.
2.1 Telescope & Site
The telescope will be integrated on site at the Summit Facility. In this sense there is not a single moment of delivery for the telescope to the LSST Observatory. Approximately 6 months prior to the start of Early System I&T, the telescope integration plan (LTS-104) specifies that the 3-mirror optical system will begin optical testing with Project Systems Engineering oversight. These tests include interferometry of the M1M3 assembly at the M3 radius of curvature to verify the M1M3 pre-shipping support matrices. This test configuration will also be used to build and refine the initial look-up tables for the elevation dependencies of the M1M3 mirror support. After these tests, M2 is tested with an on-axis Shack-Hartman wavefront sensor and surrogate mass to simulate the science camera on the rotator-hexapod assembly. A laser metrology system is used to establish initial alignment and look-up tables for M2 and the camera hexapod/rotator. There will be roughly 4 months of on-sky time with the telescope in this configuration to allow analysis of the on-axis optical aberrations and refinement of the alignment and mirror support look-up tables.
Given the tests summarized above, it is expected that the telescope will be largely functional at the start of the Early Integration and Test Phase. The telescope will be delivering SRD-like image quality to ComCam over a limited field-of-view around the optical axis and can point and track to its open loop specifications (OSS-REQ-0303). Further, the dome mechanisms are assumed to be working, including azimuth tracking, elevation tracking of the entrance opening, ventilation louvers, and HVAC system for daytime thermal conditioning. The calibration dome-screen will be installed with both the tuneable narrowband and broadband light sources functioning to specification. The “Engineering First Light” milestone coincides with the start of Commissioning and will be declared when the telescope is producing on-axis SRD-like image quality and has passed its acceptance criteria.
The LSST science Camera will be integrated and tested at the SLAC National Accelerator Laboratory per the Camera Integration and Test Plan (document LCA-40). During this phase of the Camera construction all of the camera subsystem requirements (document LSE-59) will be verified to the extent possible without integration onto the telescope. Demonstration of compliance with its requirements signifies the Camera has met its shipping readiness milestone. The camera, its support hardware, and test apparatus will then be shipped to Chile from SLAC.
Figure 2: Activities for the Telescope & Site integration and test phase showing the key telescope integration activities coming ready prior to the end of FY2019 for the start of Commissioning.
Figure 3: Level 2 milestones for the Camera construction phase, showing the camera being delivered to the summit and verified prior to the end of FY2017 – the start of Commissioning.
The Camera is scheduled to arrive in Chile via airfreight and will be brought to the Summit Facility by truck roughly 3 months prior to the start of Full System I&T. During this time the camera will be reassembled (if need be) in the camera service space at the Summit Facility, and a subset of verification tests run at SLAC will be rerun to show shipping readiness will be re-run to verify that no functional or performance damage occurred during shipping.
As part of the post-shipping evaluation the camera will be connected to the Summit Facility network. With the camera on the network, the data path between the Camera and the DM processing pipelines at the Base Facility and Archive Center will be established and verified with live pixel data from the science FPA. During this initial testing the command and control of all Camera functions with the OCS will also be verified. Successful completion of these tests will signify that the camera has met its acceptance criteria and is ready to enter the commissioning phase and start Full System Integration and Test.
2.3 Data Management
The Base Facility computing and data center infrastructure is scheduled to be installed and working prior to the start of Early System I&T. Data Management is supplying a “Commissioning Cluster” at the Base Facility that is equivalent to ~10% of the initial Alert Production computer capacity. The commissioning cluster will be used as a local resource for processing, analysing, and visualizing commissioning data. The commissioning cluster will initially have LSST Software Release v9.1 operating on it. This will provide functioning Data Management processing pipelines for Instrumental Signature Removal, Calibration Data Products, Transient Alert Processing, and nightly photometry and astrometry processing. These pipelines will have been tested and verified for two kinds of data: 1) simulated data generated for the Data Challenges used in the project development phase; and 2) legacy data from previous surveys (e.g., HyperSuprimeCam on the Subaru telescope, CFHT Legacy Survey, SLOAN Digital Sky Survey, and additional surveys currently in the early stages of operation).
The 100Gb/sec network link between the Summit and Base facilities will be installed and shown to be fully functioning. An early Science DAQ System (SDS) from the camera team will be delivered to Chile approximately 18 months prior to the start of Early System I&T. The SDS will be capable of creating and sending synthesized pixel data in the LSST format across the Summit-Base network. The operational data path (data source at the camera location on the telescope) and the service data path (data source in the Summit Facility camera laboratory) will be tested and verified using SDS synthetic pixel data, simulated image data, and legacy survey data.
Beginning in FY2020 there will be sufficient long haul network bandwidth to support the transfer of early System I&T data from the Base Facility to the Archive Center. Both the Archive Center and US Data Access Center will have sufficient capacity to archive all commissioning data and allow project personnel access.
Figure 4: A portion of the Level 2 milestones for the Data Management System leading into and covering the commissioning phase. The Data Management System grows during the commissioning effort reach initial full capacity prior to the start of Full System I&T late in FY2020.
2.4 Observatory Control System
The OCS is being developed in stages. Annual releases provide increasing levels of functionality at each stage. The purpose of this methodology is to make portions of the OCS available to developers of other subsystems that need to interface with this package. At start of commissioning the OCS software will have had its 4th annual release. In this release the OCS software functionality that will be fully implemented includes the following:
· Communications Middleware with messaging software;
· Engineering and Facility Database;
· Operator GUIs;
· Monitor software with status displays;
· Maintenance support software; and
· Application control software with sequencer to synchronize the subsystems.
2.5 Auxiliary Telescope
The auxiliary telescope (1.2m Calypso) will be installed and fully operational approximately 18 months prior to the start of Early System I&T. This includes the telescope and its control system, the spectrometer, and the software to process the spectroscopic data from raw images to calibrated spectra. The analysis software to convert time and spatially dependent spectra to the required atmospheric transmission function needed for the photometric calibration of the LSST science data is also expected to be operational prior to the start of the Commissioning period. The auxiliary telescope’s integration as part of the OCS-controlled observatory will occur during Early I&T. The atmospheric transmission function will be validated during the photometric analysis during Early I&T.
2.6 Ancillary Equipment
In addition to the main LSST observatory components described above a suite of ancillary equipment is also expected to be operational at the start of the Commissioning Phase. These include the following items:
· Science image visualization system;
· Meteorological monitoring equipment at the Summit Facility, including wind and temperature stations in the dome interior;
· Visible and IR all-sky cloud cameras;
· Water vapor microwave radiometer;
· MASS / DIMM atmospheric turbulence profiler; and
· Network monitoring equipment and software.
2.7 Software Tools and Other Capabilities
In addition to the operational deliverable systems that make up the LSST Observatory, additional display, analytic, and scripting tools will be needed to facilitate the Commissioning effort.
The observatory “quick-look” interactive image display system is needed both at the Summit and Base Facilities to start the Commissioning phase. The interactive display at the Base Facility will be connected to the commissioning cluster. The “quick look” display system includes stand-alone interactive image analysis functions using the LSST Software Stack, which will allow targeted analysis of images during commissioning independent of the DM pipelines. The analysis functions will also allow scripting so that more sophisticated analysis can be performed on multiple images from the science FPA, including the following:
· Determine the sensor-to-sensor and amplifier-to-amplifier crosstalk from a stack of images where a bright source(s) has been scanned over each amplifier segment;
· Determine photon transfer functions (measured variance versus count level) to determine amplifier gain, linearity, and read out noise from wideband dome-screen flats;
· Determine pixel-dependent shutter timing variations from alternating short-long-short integration wideband dome-screen flats.
Using the full science camera as a wavefront sensor is critical in the early stages of the Commissioning phase. This involves intentionally defocussing the camera by a known amount to obtain intra- and extra- focal image pairs to map the optical aberrations over the full field-of-view. Software will be needed to analyze the science array as a wavefront sensor along with specific optical reconstruction software to use the 189 science sensors in the FPA to estimate the system misalignment and figure errors on M1M3 and M2. This wavefront estimation software will be derived from the wavefront curvature algorithm that will be used in operations and is included in the LSST Software Stack. The optical reconstructor will be specifically calculated for the mean wavefront aberrations at the center of each of the 189 science sensors.
2.8 External Data Sets
The following data sets are expected to be available to assist in the verification of the LSST performance:
· Gaia astrometric and photometric catalogs (assuming a successful mission)
· UCAC Astrometric Catalog
· Sky Mapper Database
· SLOAN Digital Sky Survey Database
· PanSTARRS Database
· DES Database
· Known moving objects.
3 Early System Integration & Test
The scope of Early I & T (Figure 5) includes the following general objectives:
· Tests of network connectivity and bandwidth using live data between the Summit and Base Facilities and between the Base and Archive facilities;
· Tests of command and telemetry interfaces between Camera Control System and OCS;
· Build/refine telescope pointing model;
· Test Camera-Telescope Guider interface and telescope guiding functionality;
· Verify and characterise active optics performance using ComCam as a wavefront sensor;
· Refine/Build active optics look-up tables;
· Demonstrate safe autonomous scheduler driven observing operations;
· Verify time-dependent survey cadence with as built scheduler – observatory interactions;
· Test/refine instrumental signature removal pipeline and algorithms on live data;
· Test/refine Data Management photometric calibration performance on live data;
· Test/refine Level-1 data products with Data Management alert production algorithms; and
· Perform initial tests of Leve-2 data release production.
Figure 5: The sequencing of key ComCam activities during the Early I & T phase.
The above objectives will be accomplished using a commissioning camera (ComCam). ComCam uses a single science raft (144 mpix) populated with 9 engineering grade sensors to produce a 40-arcmin field-of-view at the 3-mirror telescope focus. A 3-element corrector will produce <0.3 arcsec FWHM images in g-r-i filters bands. ComCam will utilize as many of the full camera’s interfaces as possible to facilitate system level testing during this Early I&T period, including the camera SDS for science and guider sensor readout and the Camera Control System for supervisory control (shutter and filter). ComCam is integrated onto the telescope using the rotator/hexapod interface with a surrogate mass assembly to mimic the full camera mass and center of gravity (Figure 6).
Figure 6: The conceptual layout of the Commissioning Camera mounted on the rotator-hexapod at the end of the camera integrating structure. This is the configuration just prior to installation into the telescope top-end assembly. Note the two green pieces near the camera entrance are steel plates to simulate the full camera mass and CG.
3.1 Build-Refine Telescope Mount Pointing Model
Activity Scope: By measuring pointing offset between commanded position and observed position the telescope pointing model will be built and refined. This will be carried out in coordination with laser tracker measurements of deflection from the top end assembly and hexapod rotator while under full load.
· Obtain laser tracker measurements of secondary mirror and ComCam displacements as a function of elevation at various azimuth orientations in 5-degree increments. Evaluate over as wide a range temperature as possible (task can be done day or night).
· Apply deflection map to active control look-up tables and repeat measurements and tabulate residuals. If there are systematic residuals, refine deflection map and reapply to active control look-up table (task can be done day or night).
· Obtain measurement of the offset between commanded telescope position and observed position of bright reference stars over the full operating elevation and azimuth positions.
· Evaluate pointing offsets with respect to the mount model coefficients. Update mount model as needed to demonstrate and verify pointing requirements (task can only be done at night).
· Verify pointing offset commands over ComCam FOV (task can only be done at night).
3.2 Initial Guider Verification
Activity Scope: Test and verify the Camera-Telescope guider interface including: 1) defining and transferring the region of interest coordinates to the Camera guider readout control; 2)verifying the transfer of guider data (images) from the Camera guider readout to the Telescope Control System; 3) verifying acquisition of guide stars and their respective centroid calculations; and 4) verifying centroid feedback for control of the elevation, azimuth, and rotator axes.
· Configure all 9 ComCam sensors (3 for each Raft Electronics Board) to operate as guiders. Verify that the readout of the region of interest specified by the OCS/TCS is being correctly addressed.
· Use the outer 8 signals to verify the Cam-Tel guider interface for each of the required 8 inputs. The center sensor is used to monitor the centroid and mount tracking performance from the Telescope Control System. The expected guiding response bandwidth will be verified by injecting known disturbances to the telescope pointing and measuring the observed response in the reference centroid stream.
· Once the Cam-Tel interface is verified with 8 channels of guider data, scale back to a configuration where 2 REBs ("top" and "bottom" rows) are configured for guiding and 1 REB (the "middle" row) is configured for integrated "science" imaging. This will partially test the guider interface with 6 out of 8 guider inputs referenced against image quality across the field center and out to the ComCam field edge. This will verify the sequencing between shutter opening/closing, guider signals, science integration and readout, and to a limited degree control over telescope and rotator tracking.
· Verify spectral sensitivity and performance by repeating the above test through all 6 filters.
3.3 Initial Wavefront Sensing Verification
Activity Scope: ComCam will be used to verify compensation for flexure by the Camera and M2 hexapods. Interfaces, algorithms and image processing needed for curvature wavefront sensing will be verified.
· Obtain intra/extra focal images by varying the z-position of ComCam with the hexapod . POcess these images using the LSST curvature wavefront sensing and image reduction algorithms to produce wavefront error estimates on-axis and over ComCam’s FOV.
· Reconstruct the control variables used by the active optics system and correlate these with the state variables (elevation, azimuth, temperature etc…) of the camera-telescope system. Update the AOS look-up tables as needed.
· Vary the individual AOS control variables to verify the wavefront influence functions match those predicted from modelling and earlier analysis.
Obtain repeated measurements of the residual wavefront error over as wide a rande of system state variables as possible to understand limitation in predicted performance (e.g. hystoresis, non-linear behaviour, therma gradients etc…).
3.4 Scheduler and Autonomous Operations Testing
Activity Scope: This is a concentrated effort to commission the LSST scheduler in all its modes of operation. This activity is divided into four 2-week periods that are meant to ramp up autonomous operations in order to safely demonstrate consistent autonomous operations over a 1-week period. Additional single image performance verification will occur during this period to show full compliance with all single image SRD specifications.
· Initial scheduler commissioning. At completion the LSST system is demonstrated to run autonomously over a minimum 1-2 hour period, with various fail-safe modes demonstrated. In parallel with the observing effort there is an engineering effort to respond to scheduler issues uncovered during this period. · A demonstration of clean autonomous operation lasting a minimum of 4 hours. Along with further commissioning of various fail-safe modes and safety provisions. · A demonstration of clean autonomous operation lasting a minimum of 8 hours (1 full night) along with further commissioning of various fail-safe modes and safety provisions · A demonstration of clean autonomous operation lasting a minimum of 8 hours each night for a 1-week period along with further commissioning of various fail-safe modes. During this time mini-surveys will be conducted with ComCam. Upon the conclusion of this effort, there is a readiness and safety review for scheduler-driven autonomous operation that will be needed for the remainder of the commissioning period.
3.5 Mini-Survey and DM Algorithm Testing
Activity Scope: Using either scripted or scheduler driven observing campaigns obtained on-sky data for the purpose of exercising all aspect of the nightly data processing algorithms and pipelines.
· Obtain instrumental calibration data (monochromatic and wide band dome flats, bias frames, etc..) to test the Calibration Data products pipeline and the Instrumental signature removal algorithms.
· Verify lab-measured crosstalk coefficients with those derived from on-sky measurement and Data Management’s cross talk estimating algorithms.
Combine ComCam data from the auxiliary telescope and other ancillary instruments to exercise the Data management’s photometric calibration pipelines.
4 Full System Integration & Test
The scope of the full systems integration and test period includes:
· Acceptance tests for each of the three major subsystems to demonstrate that the criteria that are prerequisites for starting System I&T as outlined above have been satisfied;
· Tests for remaining subsystem requirements that need the presence of another subsystem to show compliance;
· Verification of command and control of the three LSST subsystems with the Observatory Control System;
· Demonstration that the Observatory System Specifications (OSS, LSE-30) have been met at the end of System I&T, along with the following:
o Test camera + telescope integrated functions;
o DM + camera + telescope interaction and meta-data transfer;
o Testing DM algorithms at the base with “real” data; and
o Calibration operations & pipelines tested.
· Initiation of Data Quality Analysis on “real” camera data.
4.1 Camera-Telescope Integration
The key camera-telescope activities during the system integration and test period have been identified, time estimates made, and a schedule developed (Figure 7). Once the Camera-Telescope pair is working well together at the conclusion of constructing AOS look-up tables, there is an extended period for scheduler mini-surveys. These are presented in summary form below with they key tasks for each activity listed.
Figure 7: The sequencing of key activities for Camera-Telescope integration. Note the inclusion of a 6-week period near the end of this phase to service both the Telescope and Camera.
4.1.1 Fixtures and Handling
Activity Scope: All fixtures needed for handling the camera at the Summit facility are checked and verified for proper fit.
· Safety measures for handling the camera are checked and verified. Handling procedure documentation is updated to reflect any changes that are made.
· "Dry runs" of all handling procedures needed to install the camera on the telescope are executed without the camera. Any procedure modifications are incorporated into the LSST Observatory documentation
· Any changes to fixtures needed to adapt to any refinement of the installation procedures are made.
4.1.2 Camera-Telescope Physical Integration
Activity Scope: The camera is mated with the top-end integrating structure of the telescope, moved from the Summit Facility camera lab to the dome floor, and installed on the telescope.
· The telescope integrating structure (including the camera support hexapod and rotator) is removed from the top end assembly, mated with the handling cart, and transported to the camera staging area in the Summit Facility;
· The camera is mated to the top-end integrating structure;
· The dome crane is fitted with the camera lifting fixture;
· The camera + hexapod + rotator + integrating structure are physically moved from the camera staging are to the dome floor using the 80T reciprocating vertical conveyor (RVC).
· Camera insertion guide rods are installed on the telescope top-end assembly;
· The camera + hexapod + rotator + integrating structure are physically installed and secured into the telescope top-end assembly;
· All camera utility connections are made to the telescope top-end assembly;
· Basic camera functionality is verified through the Camera Control System; and
· Connectivity between the Camera Control System and Observatory Control system is established and verified.
Note: No on-sky data from the camera + telescope is expected during these activities.
4.1.3 Initial Camera-Telescope Testing
Initial Camera-Telescope testing consists of several multi-tasked activities that include daytime calibration measurements and night-time on-sky observations. These activities are interleaved throughout a 40-day time block.
22.214.171.124 Pre-Observation Checkout and Characterization
Activity Scope: The basic functionality of camera and telescope pair will be verified and initial instrumental characterization established.
· Verify that all Camera functions can be controlled through the OCS, both locally in the Summit Facility and remotely at the Base Facility; · Establish and verify connectivity between the camera on the telescope and the Data Management System; · Verify that camera telemetry is being recorded by the OCS's Engineering and Facility Database and that the telemetry is consistent with reference measurements made during acceptance testing at SLAC and re-verification done in the summit facility Camera servicing area; · Exercise the process and procedures needed to swap out one of the internal filters with the filter currently in storage; · Verify the filter exchange mechanism over operational elevation range, the position repeatability, and the time for exchange; · Verify nominal telescope mount performance with camera installed. · Characterize the on telescope performance of the Camera Focal Plane Array using the calibration flat field screen including:
o Photon transfer curves to determine amplifier linearity, noise, and gains; o Shutter timing uniformity, repeatability, and pixel dependent corrections; o Narrowband dome flats from the dome screen sampling each filter at 1nm intervals; o Wide band (white) dome flats from the dome screen through each filter; o Zero-exposure bias images for mapping low level additive pixel structure; o Dark images, include long darks for verifying dark current specs; and o Shutter-leakage characterization by comparing long darks with and without the wideband dome screen illuminating the entrance pupil.
126.96.36.199 Initial Camera-Telescope Alignment
Activity Scope: Determine the displacement of the as-built Camera – Telescope as a function of elevation, azimuth, temperature and other identified system dependencies needed for active compensation.
· Using the telescope-mounted laser tracker determine the camera alignment dependencies over the full range of elevation, azimuth, and rotator angles. Build initial camera alignment look-up tables using these measurements. · Verify that look-up tables maintain camera alignment within the measurement tolerance of the laser tracker.
188.8.131.52 Initial On-Sky Characterization
Activity Scope: Obtain on-sky data to characterize the camera-Telescope pair and provide the data management system with first real data for algorithm testing and refinement.
· Establish and verify feedback to the TCS from the corner raft guide sensors; complete final verification the camera-telescope guider interface. · Map the position of best focus using “focus-sequences” over the full focal-plane-array as a function of elevation, azimuth and rotator angle, adjust hexapod control to best fit focal surface, and update hexapod control look-up tables as needed; · Map the PSF size and shape over the full FPA as a function of elevation and azimuth; · Map the optical aberrations over the full FPA using the camera FPA as a wavefront sensor; · Process all images through the DMS instrumental signature removal pipeline; · Update calibration data products for the instrument signature removal including:
o Bias & dark master images o Narrowband flat images from the dome screen in each filter o Wideband flat images from the dome screen o Shutter timing corrections o Illumination corrections
· Characterize stray and scattered light versus lunar angle and azimuth to verify that the FRED point source transmittance function matches the as-built system; and · Obtain early data for DM pipeline debugging
4.2 Active Optics Verification
Once the basic camera-telescope integration and characterization is completed, the focus of the Camera-Telescope integration activities turns to testing and verification of the active optics system. The tasks used to calibrate the wavefront sensors and those needed to verify the optical reconstructor will be interleaved. It is expected that these two activities will have to iterate with each other to achieve desired performance.
4.2.1 Wavefront Sensor to FPA Calibration
Activity Scope: The four dedicated wavefront sensors used for alignment and figure control will be calibrated to the as built focal-plane-array and telescope active optics control system.
· Using the full science camera FPA, alternating intra-, extra-, and in-focus image sets will be used to calibrate the focus position of the wavefront sensors with respect to the FPA. The mean of the focus Zernike coefficient (Z4) is determined for each of the 189 science sensors from the intra- and extra-focal image pairs. A best-fit plane to the 189 mean Z4 coefficients is determined. The hexapod is adjusted iteratively until the mean focus error over the FPA is zero. The Z4 focus coefficient offsets for each of the corner wavefront sensors are recorded as a function of elevation, azimuth, and rotator angle. Updates are made to the active optics look-up tables as needed. · Using the method described above, the full science array will be used as a curvature wavefront sensor. The wavefront errors of the 189 science sensors will be evaluated using separate optical reconstructors to evaluate consistencies in determined alignment and surface error corrections from the four wavefront sensors alone. If needed, offsets to the aberration coefficients from the corner wavefront sensors will be used to optimize the overall wavefront performance over the science FPA. · The Instrument Signature Removal pipeline will process all on-sky images. · The transient alert pipeline algorithms will be tested on the in-focus images. · Calibration data products for the instrument signature removal will be updated including:
o Bias & dark master images o Narrowband flat images from the dome screen in each filter o Wideband flat images from the dome screen o Shutter timing corrections o Illumination corrections
4.2.2 Optical Reconstructor Verification
Activity Scope: The conversion from wavefront error to misalignments and mirror surface errors will be verified for each degree of freedom in the active optics system.
· Each of the 10 degrees of freedom (camera =5, secondary mirror=5) used for rigid body alignment will be perturbed by known amounts increasing in amplitude. For each perturbation on-sky wavefront measurements will be made using both the four dedicated wavefront sensors and the camera itself ( as described above). The wavefront errors from the four sensors will be converted to misalignments to determine the efficiency of recovering the known error and the linear response range. · Each of the controlled bending modes used for surface figure control on the primary-tertiary and secondary mirrors will be perturbed by a known amount (based on force patterns). For each perturbation on-sky wavefront measurements will be made using both the four dedicated wavefront sensors and the camera itself. The wavefront errors from the four corner sensors and the 189 science sensors will be independently converted to surface errors to determine the validity of the force functions, the efficiency of recovering the known error, and the linear response range. · The Instrument Signature Removal pipeline will process all data from the camera. · In-focus data will be processed by the transient alert pipelines and will be coordinated with the Data Management integration activities.
4.3 Data Management Integration
In parallel with the Camera-Telescope integration activities the Data Management pipelines will be tested using live camera data. The data from the full Camera will initially be sporadic and in the form of the occasional in-focus images taken during the Camera-Telescope Integration activities. At the conclusion of the Active Optics Verification there will be an extended period of time dedicated primarily to scheduler driven mini-surveys for the purpose of feeding large quantities of full Camera data to the DM processing pipelines. The sequencing of DM pipeline testing in the first year of commissioning is shown in Figure 5, with details in the sections that follow.
4.3.1 Networking Bandwidth Verification
Activity Scope: Test all interfaces (as defined by the system ICDs) that utilize the Mountain-Base network and the long haul Base – Archive network using full bandwidth Camera data from the telescope.
· Pixel transfer from the Camera science data system (SDS) interface to Data Management for both raw and crosstalk corrected data. · Verify Data Management can transfer from the 2-day data store residing in the Camera SDS. · Verify OCS – DM command interfaces, status, data quality, Engineering Facility Database access etc… · Verify network burst capacity for “catch up” mode.
4.3.2 DM-Telescope-Camera Interface Verification
Activity Scope: Test the interface connections between DMS and the Telescope, Camera, and Engineering & Facility Database. Initiate testing for Science Data Quality Assessment and computational performance.
· All interfaces (as defined by the ICDs) will also be tested in their operational configuration, including:
o Camera SDS - DM interfaces (science data transfer, raw and cross-talk corrected) o Telescope - DM interfaces (power/cooling supply/reliability, mountain - base network transfers at 3 Gb/s rates) o OCS - DM interfaces (command, status, data quality, daily transfer of Engineering and Facility database from Summit to Base)
· Science Data Quality Assessment will be done via examining SDQA pipeline output from images taken from the Camera mounted on the Telescope. · Verify that metadata needed by DM processing pipelines is being provided either in the image header or from the Engineering and Facilities Database. · Exercise transferring the Engineering and Facilities database to the Archive Facility at NCSA for the purpose of daily back-up and archiving.
4.3.3 Initial Alert Production and Calibration Pipeline Tests
Activity Scope: Initial Testing of database, pipeline, and data access performance using full bandwidth Camera data as provided during the first phases of Camera-Telescope Integration.
· Test database and pipeline data access performance by repeatedly operating the Calibration Data products pipeline and Alert Production for an entire night, from acquisition of science data from the SDS, up to and including the creation of alerts and delivery to a local VOEvent broker (but not the further distribution of alerts). · Serve pipeline input data from the database (e.g. known solar system objects) at full operational rates (burst). · Ingest pipeline output data into the database at full operational rates (burst). · Characterize instrumental features seen in the data including but not limited to:
o Wind speed / direction vs DIQ (characterize mount/camera vibration and procedure for dome vent control) o Stray and Scattered light vs lunar angle (verifications of FRED PST) o Characterize Ghosts vs field vs filter o Determine X-talk correction matrix o Characterize elevation and azimuth dependence of the system o Characterize temperature dependence of the system
4.3.4 Mid-Scale Calibration Products Pipeline Tests
Activity Scope: Test the Calibration Products Production and the generation of Calibration Data Products for Alert Production.
· Process wideband and wavelength dependent dome-screen flats to produce reference flat field images for each filter. Characterize temporal stability. · Process high-density rastered fields to produce illumination correction images for each filter. · Process image stack and Camera metadata to produce pixel-dependent shutter timing correction map. · Process image stacks to produce reference zero exposure bias image and reference 15 sec dark current image. · Process spectroscopic data from calibration telescope to produce wavelength and temporally dependent atmospheric transmission function. · Process image stack to determine chip-to-chip and amplifier-to-amplifier pixel crosstalk correction matrix.
4.3.5 Mid-Scale Alert Production Piepline Testing
Activity Scope: Operate, refine, and administer the Alert Production Pipeline for sustained scheduler-driven multi-night observing campaigns.
· Test Alert Production pipelines by repeatedly operating the Alert Production processes for sustained periods, from acquisition of science data from the SDS, up to and including the creation of alerts and delivery to a local VOEvent broker (but not the further distribution of alerts). · Periodically install new software releases of these pipelines as improvements are made during this testing phase. · Characterize and correlate instrumental features seen in the data with the measured system state variables including but not limited to:
o Wind speed / direction vs DIQ (characterize mount/camera vibration and procedure for dome vent control) o Stray and Scattered light vs lunar angle (verifications of FRED PST) o Characterize Ghosts vs field vs filter o Determine X-talk correction matrix o Characterize elevation and azimuth dependence of the system o Characterize temperature dependence of the system
4.3.6 Data Release Production
Activity Scope: All data taken during the scheduler-driven mini-survey observations will be processed through Level 2 data release pipelines The Science User Interface will be tested using these data products.
· The Data Release Production will be tested by periodically processing accumulated commissioning data up to that point. This processing will be paced by the production of commissioning data. Whenever the Observatory produces data meeting the single image quality requirements, a monthly processing of that data is planned (on servers hosted at NCSA). Princeton will support enhancements and maintenance of the DRP software. · Access to data products fby the LSST headquarters from the Data Center located at the NCSA Archive Facility will be verified using the LSST Science User Interface tools. Performance will be evaluated and upgraded as needed.
5 Science Verification
The science verification period is structured around demonstrating that the system functional and survey performance specifications given in the Science Requirements Document and LSST System Requirements are being met. For planning purposes we have structured the Science Verification period into a 4-phase frame work (Figure 8); 1) a 3-month period where the emphasis is on verifying compliance with single-visit performance requirements; 2) verification of the full survey performance requirements for image stacks and area coverage; and 3) final science verification and acceptance tests for operations readiness. The Science Verification framework includes time for engineering related activities throughout, with more engineering time at the beginning and transitioning to something near early operational levels by the end.
Figure 8: The framework for the 1-year Science Verification period being used for planning purposes has four phases: 1) Single image verification; 2) Autonomous scheduling and operations testing; 3) Full survey performance verification; and 4) Final science verification and operations readiness.
Figure 9: The science verification matrix shows methods that are to be used to verify the SRD performance requirements.
5.1 Single Image/Visit Performance
Activity Scope: The first 4-months of the Science Verification is divided equally into four 1-month activities divided approximately 50/50 between on-sky observing and engineering with an emphasis on verifying SRD image quality specifications. At the end of this period compliance with the SRD single image specifications shall be demonstrated per the methods indicated by the Science Verification Matrix (Figure 6).
· Measure delivered image quality (DIQ) performance (FWHM & ellipticity) over the full FOV on successive exposures and visits. Correlate measured DIQ in time, Alt, Az, and rotator angle with MASS/DIMM measurements of the atmosphere wavefront measurements of the field dependent optical aberrations. After the effects of the atmosphere are removed, test system image quality against SRD specifications as identified in the verification matrix. · Evaluate active optics look-up tables for systematic wavefront-based correction versus altitude, azimuth and rotator angle. Update active optics look-up tables as necessary to minimize systematic corrections. · Apply photometric color corrections using the atmospheric transmission function determined from the auxiliary telescope and test against SRD photometry requirements as identified in the verification matrix. · Test the data release production pipelines using all accumulated data at the end of each 1-month period.
5.2 Full Survey Performance Verification
5.2.1 10-year Stacked Image Performance
Activity Scope: Demonstrate compliance with the stacked image specifications over a limited number of fields with the number of visists equivalent to a full 10-year survey (825 total visits as defined in SRD spec Nv1). Each trial is in itself a mini-survey where its data will be processed as if it were from the regular survey and made available to the LSST Commissioning team for analysis.
· A concentrated observing campaign to demonstrate image depth compliance (as defined in SRD Table 22) with the full survey equivalent image stack on a limited set of LSST fields (approximately 5-10). · A concentrated observing campaign to demonstrate final PSF shape residuals (as defined in SRD Table 25) with full 10-year survey equivalent stack on a limited number of fields (approximately 5-10). This campaign will require better than average seeing conditions to show compliance.
5.2.2 !0-year Area and Temporal Coverage
Activity Scope: Demonstrate compliance with meeting the area and temporal coverage specifications.
· Demonstrate that the rate of area coverage is sufficient that the SRD area specification Asky can be met over the 10-year survey lifetime. These tasks will result in a large area mini survey with a limited number of visits for each field and limited depth. Data from this effort will be processed as regular survey. · Demonstrate compliance with the full survey SRD temporal sampling specifications detailed by RVA1, RVA2, RVA3. This effort will result in a mini survey over a modest area (~2000 sq. deg) with a fraction of the area proportionally scaled to SRD temporal coverage specifications to show compliance.
5.3 Parallel Data Management Activities
In parallel with the science verification tests outlined above, the LSST Data Management system will undergo additional verification tests. These tests will cause periodic updates to the software algorithms and the data processing pipelines. Included in these activities are updates to the Data Management System infrastructure at the Base and Archive Facilities as well as the Chilean and US DACs. The sequencing of key science verification activities in Data Management is shown in Figure 10.
Figure 10: The key science verification activities and milestone for the Data Management System.
5.3.1 Final Archive Center and US DAC Integration and Testing
Activity Scope: Test the Archive Center infrastructure by executing Data Production and transfer of Data Releases to the Data Access Centers.
· Raw image data will be transferred at 40 Gb/s from the Base Center to the Archive Center whenever data is collected. · Data Release Production will periodically process the accumulated commissioning data up to that point. This processing will be paced by the rate of production of commissioning data. Whenever the Observatory produces data meeting the single image quality requirements, a monthly processing of that data is planned (on servers hosted at NCSA). · New software releases of these pipelines will occur periodically during this testing phase. These software releases are developed, integrated, and tested using infrastructure located at and supported by NCSA. · A disaster recovery test will be performed wherein a complete set of all commissioning data will be recovered from offline storage, and Catalogs from the DAC will be restored to the Archive Center.
5.3.2 Final Calibration Data Products Verification
Activity Scope: Verify accuracy and correctness of the Calibration Products Production and the generation of Calibration Data Products for Production processing using commissioning data.
· Calibration Data Products will be created on servers hosted at NCSA, by UW-developed CPP software, and delivered to the Base Center via 3 Gb/s network for use in processing commissioning data by the Alert Production. UW will support enhancements and maintenance of the CPP software.
5.3.3 Level 2 Data Release Production Verification
Activity Scope: At the end of each observing block process all image data obtained to date through the Data Release Production pipeline.
· Test the Data Release Production by processing accumulated commissioning data up to that point. This processing will be paced by the production of commissioning data. Whenever the Observatory produces data meeting the single image quality requirements, a monthly processing of that data is planned (on servers hosted at NCSA).
5.4 Other data needed during commissioning
This section contains a list of additional data sets needed during the commissioning period that may not otherwise be identified but are deemed useful. These include:
· Raster single field across each detector for determination of illumination corrections, initial color term determination, and verification of astrometric solutions. · Dense rastering with 70-90% overlap of an area 3-5 times the field of view to determine illumination correction from the self-calibration algorithm. · Repeated observations of fields across various airmasses, in multiple bands, to determine photometric repeatability. · Repeated observations of celestial pole field, at different rotations, to understand fixed-airmass atmospheric systematics. · Observations of celestial pole field though different amounts and kinds of clouds, to verify how well we suppress transparency variations. · Other engineering time for pointing model, wavefront correction tweaking, etc.
6 Operations Readiness
This section is meant to define the condition, terms and criteria used to determine that the LSST is ready for operations.
6.1 Operations Readiness Mini-Survey
The final survey verification phase will consist of a continuous mini-survey lasting at least 30 days to demonstrate readiness for full LSST science operations. This survey will be under full autonomous scheduler-driven operation. The minimum thirty days of survey operations is sufficient to cover the operational cycle over a full lunation, including the u-band filter swap over dark time. Assuming the typical usable weather fraction, the 30-day mini survey will yield approximately 20000 visits sufficient for multi epoch coverage of the sky in 2-3 filters or a single epoch with all 6 filters (see A.2 example mini-survey #1).
The data from this effort will be treated as if it were part of normal survey operations and will be an early release data product for the science community. This data will also be used to start boot-strapping the planned 10-year survey.
Figure 11: An example of the sky coverage and visit density achievable in a 30-day period. Three “deep drilling” fields are visible as well as areas with higher temporal sampling (dark blue).
6.2 Operations Readiness Review
At the end of the Commissioning Phase of the MREFC LSST construction project an Operations Readiness Review will be undertaken by an external panel, jointly appointed by the Department of Energy and the National Science Foundation, in consultation with the LSST project team. In order for the LSST project to declare that the MREFC funded construction project is complete and is ready to enter the “steady state” Operations Phase the shall demonstrate that following requirement been met:
1. The project team shall demonstrate that the integrated LSST system (Camera, Telescope & Site and Data Management System – does not apply to EPO) has met the technical specifications enumerated in the LSST Observatory System Specifications document (LSE-30);
2. The project team shall characterize and document the performance of the integrated LSST system with respect to the survey performance requirements and specifications enumerated in the LSST System Requirements and LSST Science Requirements documents (LSE-29 & LPM-17 Sec. 3 respectively);
3. The project team shall conduct an autonomous scheduler driven Operations Readiness mini-survey lasting at least 30 days;
4. The project team shall process the data from the Operations Readiness mini-survey to produce a Level 2 Data Release and make it available to the Commissioning Team through the Science User Interface;
5. The project team shall demonstrate that the integrated LSST system can collect and process time-domain Level 1 data products, including the generation and distribution of alerts;
6. The project team shall demonstrate that the integrated LSST system can monitor and assess the quality of the data as it is being collected;
7. The project team shall demonstrate that relevant metadata are being collected and archived;
8. The project team shall deliver a complete set of documented operational procedures and supporting technical documents needed to operate the LSST as a scientific facility for the purpose of conducting a 10-year survey; and
9. The project team shall deliver all reports documenting the as-built hardware and software including: drawings, source code, modifications, compliance exceptions, and recommendations for improvement.
Non-compliance exceptions to the above requirements will be considered following internal and external reviews of the assessed performance and operational impact.
7 Pre-Operations Engineering
In parallel with the analysis of the 30-day mini-survey data, the LSST Observatory will enter a 45-day “shutdown” period where on-sky observations will halt. At this point in time, more than two years will have elapsed since the start of Early System I & T, which places the LSST Observatory on schedule for its 2-year major maintenance and servicing.
7.1.1 M1M3 Mirror Recoating
Activity Scope: Remove, strip, clean, and re-coat the M1M3 mirror surfaces. Reinstall M1M3 mirror back into telescope.
· Remove Top-End Integrating Structure with Camera and transfer to Summit Facility camera lab. · Install camera dummy mass to allow the telescope to point to zenith for removal of the M1M3 mirror cell. Remove M1M3 mirror assembly and transfer to Summit Facility re-coating plant. · Strip old coating, clean and re-coat mirror surfaces. · Re-install M1M3 in telescope and prepare to receive the top-end integrating structure with the camera.
7.1.2 Camera Maintenance and Servicing
Activity Scope: Clean, service, perform maintenance, and replace shutter.
· Replace camera shutter with “fresh” operational unit; · Inspect, service – repair filter mechanisms; · Clean internal camera optics; · Inspect, service, and repair utility trunk electronics
8 Commissioning Management and Staffing
Responsibility for the Commissioning Phase of the Construction Project is assigned to the LSST Systems Engineering Manager and Systems Scientist. The commissioning team will be assembled from the existing systems engineering group and the necessary resources from each of the three technical teams. The technical resources from the DM, Telescope, and Camera teams will be assigned to the commissioning effort but remain affiliated with their technical teams. The three subsystem Project Managers remain on the project to provide the employee supervision functions and to assist the project Systems Engineering Manager and Systems Scientist with the staff management during commissioning.
All system integration and science verification activities shall be defined and coordinated by the LSST project systems engineering office. The Project Systems Engineer and System Scientist will be responsible for the primary deliverables from the Commissioning Phase and the day-to-day assignments and activities in the commissioning plan. The Project Systems Engineer and System Scientist will be responsible for prioritizing and defining the commissioning activities to ensure these deliverables are met. The roles and responsibilities of key staff are summarized here:
The LSST Director and Project Manager will continue to hold overall authority over all commissioning activities, schedule, and budget.
The LSST Safety Staff will continue to provide the teams with the guidance and oversight to maintain a safe working environment at all LSST locations. As appropriate, and particularly for integration activities, the Safety staff will be on the summit assisting with daily briefings and planning.
The Systems Engineering Manager and Systems Scientist will be responsible for determining and directing the day-to-day activities necessary to complete commissioning effort.
The Data Management Project Manager continues to provide the direct personnel supervision and/ or contracts for the DM staff assigned to the commissioning effort. The DM team is continuing to finalize their deliverables during this period in parallel with the commissioning effort.
The Camera Project Manager provides the liaison with the DOE supported Camera Operations staff. This staff will include the builders of the camera necessary to support the final check-out of the camera on the mountain and the integration and test of the camera on the telescope. This staff will also include the science team to support the data analysis and science verification efforts.
The Telescope and Site Manager will continue to provide the direct personnel supervision for the Telescope and Site staff assigned to the commissioning effort. The T&S Manager will also be responsible for the day-to-day operation of the site during this period to coordinate appropriate maintenance and regular logistic activities.
The Project Manager and each of the subsystem Managers will work together to establish a single coordinated commissioning team led by Systems Engineering. While the Subsystem Project Managers are necessary to support the staff supervision and assist with the commissioning efforts, the leadership will be provided by only Systems Engineering with the authority of the Project Manager.
8.1 Commissioning Oversight
As with many projects the LSST will face enormous pressure from its user community to make its data available to the public as quickly as possible. The project team believes that this issue is best handled by an early ramp up of a partial operations staff. Data of suitable quality can be turned over to the operations team with minimal impact on the construction team. The operations staff can then assist users in working with the data and can provide feedback on data quality to the project team. The ground rules for accessing commissioning can then be worked out by the operations staff in conjunction with LSSTC, AURA, and the funding agencies. The Director may choose to establish an external advisory committee to handle the inevitable tensions.
8.2 Commissioning Staffing
The 3 technical teams from the Telescope & Site, Camera, and Data Management subsystems will be managed as single team during the commissioning period. The Telescope and Site and Data Management teams will be supported by the NSF MREFC construction funding, where the Camera team will be supported from DOE operations funding. This effectively forms a single technical team that shall take direction and priorities for day-to-day activities from the Project Systems Engineering office. The make up of this commissioning focused team and its distribution by skill type over the full commissioning period is given in table below. The Project Office will maintain existing administrative support during the Commissioning Phase.
In addition to the technical team, the Project will add a dedicated team of scientist and post-docs, whose purpose will be to evaluate the science quality of the commissioning data and provide feedback to the technical team. The science quality assessment will be based primarily on the demonstrating the SRD performance requirements and extending this analysis “user level” science programs.
The science team consists of the System Scientist and a senior Commissioning Scientist, who will take the lead in assessing the science data quality and be the primary contact point with the Project Scientist and Systems Engineer to coordinate observing planning and scheduling. Supporting the Commissioning Scientists are 3 junior scientist and 3 post-docs. There is also 1 rotating scientist position that provides support for binging scientist to the project for extended periods who otherwise could not commit to the full duration of commissioning. This staff will very likely transition to operations when commissioning is completed.
Figure 12: Full Time Equivalent resources from the load levelled PMCS-3 that make up the commissioning team.
FY20 FY21 FY22 Com. Scientists 5.3 8.7 11.3 DM Scientists 3.5 4.5 3.9 TS Scientists 2.2 2.5 2.7 Science Team Total 10.8 14.7 16.0 Engineering 7.0 6.2 6.8 Technicians 5.2 6.0 7.6 SW Engineering 11.4 12.1 8.6 Technical Team Total 23.7 24.4 22.9 Commissioning Total 34.4 39.1 38.9
One of the purposes of the 30-day mini survey described above is to begin the survey bootstrapping necessary to enable full functionality of the survey data analysis. “Bootstrap” here means that the full functioning of the system requires data that can only be gathered once the system itself is fully functioning. Full functionality, therefore, must be achieved iteratively with each bootstrap item improving in quality. Here we have identified the needed bootstrap items that will be obtained in part from data obtained from the operation readiness mini-survey, these include:
· Co-added Images: Prior to creation of detection co-adds, only single frame measurements can be supported. Over time co-added images will be produced for deep detection used for “forced photometry”. · Subtraction (image differencing) Templates: Image differencing is strongly dependent on the quality of the differencing template. Selection of quality templates will require many high quality images and will be initiated from the mini-survey data. · Astrometric Standards: These are needed for generating high quality WCS. We can possible start with previous surveys (e.g. GAIA), but will need to quickly add data from the LSST survey to achieve the desired density of high quality references per CCD. · Photometric Standards: Early quality standards are need for the nightly alert production. We will need to bootstrap from existing standards to LSST data to provide the reference source density desired per CCD. · Standards for “Global” Calibration: These will need to be carefully cleaned of low-level variability as the calibration accuracy improves and the time baseline lengthens. · Moving Object Catalogs: We will either start with an empty catalog or one populated from a precursor survey. The initial catalog will be relatively “poor” and will lead to “leak through” of moving objects as transients or variables. · Variable Identification: This will be built up over time and is needed by the moving object processing and vice versa. · Generalized of variability: We will need an object history for alert classification. · Object astrometric models: These will require time to become reliable for producing proper motions and parallaxes. It may be possible to use precursor surveys (e.g GAIA, SKYMAPPER, Pan STARRS) to seed the models. · Object Catalogs: These can only be built up as images accumulate. Catalogs will start out empty, but will begin to be populated from the final mini-survey prior to the start of operations.
9.1 Example Mini-Survey
Mini-survey #1: The entire survey region is 18,000 sq degrees, and the 10-year survey achieves of order 150 visits total in each of r,i,z,y, and 60 in u and g--a total of 4x150+2x60=720 to 800***note this doesn’t add to the 825 requirement visits to each part of the sky, total. If we allocate the best and most photometric 10% of workable nights in the second commissioning year to a mini-survey, that’s 1% of the total survey so we would get about 7 visits to each region on the sky, to spread across the passbands. If this is split between r and i, so that we get a color for each object, we would be at 3 visits per field per band. This would allow the following:
i. Full “uber-cal” validation in two bands. ii. Scaling tests for N dependence. iii. Gives first epoch across entire sky at close to survey depth, for eventual proper motion comparisons. iv. Provides CMD in i, r-i for entire sky. v. Initial designation of variable objects, feeds veto list for subsequent classification of frame subtraction variables. Alternatively, we could spend the 7 visits doing a single-epoch 6 band map of the entire survey region, to single-visit depth in each band. Need to learn how to properly do cosmic ray rejection from just two images, though. Mini-survey #2: An alternative mini-survey in 10% of the time in science verification year would be full depth over a partial area, presumably starting at dec=90 and coming North. Based on above computation, 0.1 survey-years gives us a coverage of 18000*7=126K square degree*visits. If we go to survey depth with 800 visits across all bands, that would be area of ~160 square degrees. So only 16 pointings! Cutting back to 400 visits total doubles the area to 320 square degrees, or 32 pointings. This would be all RA’s from dec of -90 to dec of -80.