Large Synoptic Survey Telescope (LSST)
    Observatory Control System
    Requirements
    German Schumacher
    LSE-62
    Latest Revision June 2, 4 201 1
    This LSST document has been approved as a Content-Controlled Document by the LSST Change
    Control Board. If this document is changed or superseded, the new document will retain the Handle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. Additional information may be found in the LSST CCB
    minutes.
    Donald Sweeney CCB Chairman
    Charles Claver CCB
    Project Manager
    System Engineer

    LSST
    Observatory Control System Requirements
    -62
    LSE
    6/24/2011
    The contents of this document are subject to configuration control and may not be changed, altered, or their provisions
    waived without prior approval of the LSST Change Control Board.
    i
    Change Record
    Version
    Date
    Description
    Owner name
    1
    5/31/20 11
    Initial version
    G. Schumacher & F.
    Delgado
    2
    6/14/2011
    General edits
    F.Delga do
    3
    6/24/2011
    General edits
    F.Delga doe

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    Table of Contents
    OCS Requirements ....................................................................................................................3
    1 OCS Functional Requirements ........................................................................................3
    1.1 Perform Observations................................................................................................................3
    1.1.1 Science Observation..............................................................................................................4
    1.1.2 Calibration Observation..........................................................................................................4
    1.1.3 Engineering Observation........................................................................................................4
    1.2 Perform Survey...........................................................................................................................4
    1.2.1 performSurveyParameters.....................................................................................................4
    1.2.2 Schedule Survey....................................................................................................................5
    1.2.2.1 Fully automatic scheduling...............................................................................................5
    Obtain candidate observations automatically ..............................................................................5
    Rank candidates..........................................................................................................................5
    1.2.2.2 Schedule Science Programs............................................................................................6
    Keep track of each science program progress ............................................................................6
    Observations Database............................................................................................................6
    1.2.2.3 Optimize observing time ..................................................................................................6
    Maximize science programs ........................................................................................................6
    Minimize slew time.......................................................................................................................7
    Estimate slew delay for candidate observations ......................................................................7
    1.2.2.4 Dynamic adaptation to changing external conditions ......................................................7
    1.2.2.5 Update Survey Parameters..............................................................................................7
    1.2.2.6 Schedule Calibration and Maintenance programs...........................................................7
    1.2.2.7 Image Processing Control................................................................................................8
    1.2.3 Survey Lifetime.......................................................................................................................8
    1.2.4 Survey Time Allocation...........................................................................................................8
    1.2.5 Survey Monitor .......................................................................................................................8
    1.2.6 Survey Verification .................................................................................................................8
    1.3 Operational Requirements.........................................................................................................8
    1.3.1 Operation Control...................................................................................................................9
    1.3.1.1 Hierarchical Control .........................................................................................................9
    1.3.2 Observing Mode.....................................................................................................................9
    1.3.2.1 Automatic Observation.....................................................................................................9
    1.3.2.2 Manual Observation.........................................................................................................9
    1.3.2.3 Scripted Observation .......................................................................................................9
    1.3.3 Operation Mode......................................................................................................................9
    1.3.3.1 Local Operation
    ............................................................................................................. 10
    1.3.3.2 Remote Operation.........................................................................................................
    10
    1.3.4 User Interface ...................................................................................................................... 10
    1.3.4.1 Access Control .............................................................................................................. 10
    1.3.4.2 Displays......................................................................................................................... 10
    1.3.4.3 GUI................................................................................................................................ 10
    1.3.5 Change of subsystem state without failure ......................................................................... 10
    1.3.6 Graceful degradation ........................................................................................................... 10
    1.3.7 Safety .................................................................................................................................. 11
    1.3.7.1 Interlock System ........................................................................................................... 11
    1.3.7.2 Safety Procedures ........................................................................................................ 11
    1.4 Observatory Services.............................................................................................................. 11
    1.4.1 Configuration Database ...................................................................................................... 11
    1.4.2 Engineering Facility Database ............................................................................................ 11
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 1 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    1.4.2.1 Availability of EFD contents
    .......................................................................................... 12
    1.4.2.2 Persistence of Telemetry .............................................................................................. 12
    EFD_OCSparameters............................................................................................................... 12
    1.4.3 Middleware Communications .............................................................................................. 12
    1.4.4 System Monitor ................................................................................................................... 13
    2 OCS Maintenance Requirements ..................................................................................13
    2.1 Analysis.................................................................................................................................... 13
    2.2 Maintenance Log ..................................................................................................................... 13
    2.3 Maintenance Planning............................................................................................................. 13
    2.4 System Maintenance ............................................................................................................... 13
    3 OCS Performance Requirements ..................................................................................14
    3.1 Downtime.................................................................................................................................. 14
    3.1.1 unplannedDownTime .......................................................................................................... 14
    3.2 Null Overhead .......................................................................................................................... 14
    3.3 Communications Performance .............................................................................................. 14
    3.3.1 communicationsPerformance.............................................................................................. 14
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 2 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    OCS Requirements
    Introduction:
    The Observatory Control System (OCS) is the master control system that schedules, commands,
    coordinates, and monitors the observatory. The OCS is responsible for high level observatory operations
    including user interfaces, sequencing, resource allocation and system monitoring and maintenance. The
    OCS orchestrates and controls all aspects of the observatory for all observations (science, calibration,
    and engineering) and all operation modes. The OCS coordinates the camera, telescope and data
    management subsystems for an integrated operation during the survey. Through the OCS the system can
    be started, monitored, adjusted during operations and stopped, both locally and remotely. The OCS
    provides the means to support safe observatory operations during day and night.
    The scheduling function of the OCS, considered the key component of this application, has as its main
    function the ability to handle demands from several competing science programs, with different
    requirements on cadence and sky location observations.
    Document Scope:
    The OCS Requirements document describes high-level specific requirements for the observation
    operational support to be implemented by the Observatory Control System, and it is derived from the
    Observatory System Specifications document (TBD) and from the Operations Simulator survey baseline
    document.
    Supporting Documents:
    1. LSST Observatory System Specifications document (LSE-30).
    2. LSST Operations Simulator document (TBD?).
    3. LSST Operations Concepts document (TBD?).
    4. LSST System Requirements (LSE-29).
    1 OCS Functional Requirements
    ID: OCS-REQ-0001
    Last Modified: 6/24/2011
    Specification:
    The functional requirements comprise the operations and behavior that the OCS
    implements to accomplish the data collection capabilities of the observatory.
    Discussion
    : The OCS works as the overall master control for the data collection functions of the
    observatory. The data collection capabilities comprises the capture of science data from the Camera, as
    well as, the acquisition of calibration and telemetry data system wide, needed to analyze the system
    performance.
    1.1 Perform Observations
    ID: OCS-REQ-0002
    Last Modified: 6/24/2011
    Specification
    : The OCS shall orchestrate the complete set of subsystems in the observatory to perform
    observations.
    Discussion
    : An Observation is the sequence of telescope and camera setup operations, the exposure for
    a certain time and the corresponding data delivery. These observations can be originated by a manual
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 3 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    request, or by an automatic mechanism.
    The OCS coordinates the subsystems in all the phases of an observation, such as configuration, slew,
    exposure, readout and storage of the image frames and the metadata. The Observing Modes are to be
    selectable by an operator.
    1.1.1
    Science Observation
    ID: OCS-REQ-0003
    Last Modified: 6/23/2011
    Specification
    : The OCS shall orchestrate the execution and acquisition of science data from the
    observatory.
    Discussion
    : The prime role of the OCS is to efficiently orchestrate the acquisition of the science images
    and telemetry data from the observatory at all times of the day and night.
    1.1.2
    Calibration Observation
    ID: OCS-REQ-0004
    Last Modified: 6/23/2011
    Specification
    : The OCS shall orchestrate the acquisition of calibration data from the observatory.
    Discussion
    : For acquiring calibration data, the OCS coordinates additional hardware that is not normally
    utilized for regular science observations.
    1.1.3
    Engineering Observation
    ID: OCS-REQ-0005
    Last Modified: 11/30/2010
    Specification
    : The OCS shall orchestrate the execution and acquisition of engineering data from the
    observatory.
    Discussion
    : This data is associated to the maintenance plan developed for the observatory.
    1.2 Perform Survey
    ID: OCS-REQ-0006
    Last Modified: 6/23/2011
    Specification
    : The OCS shall control all the subsystems to conduct a survey over
    Asky
    area of sky; with
    a median depth of
    Nv1Sum
    , using
    FC
    filters during a life time of
    surveyTime
    .
    Discussion
    : The parameter
    Asky
    is defined in LSR-REQ-0098 as 18000 SquareDegrees.
    The parameter
    Nv1Sum
    is defined in LSR-REQ-0098 as 825 visits.
    The parameter
    FC
    is defined in LSR-REQ-0082 as ugrizy.
    The parameter
    surveyTime
    is derived from OSS-REQ--0097 as 10 years.
    The cadence of visits and filter usage distribution is determined by the science programs demands
    handled by the scheduler component of the OCS. Final priorities are set by an survey overseers
    committee.
    1.2.1
    performSurveyParameters
    Last Modified: 6/22/2011
    Description
    Value
    Unit
    Name
    The total area of sky covered by the median
    18000
    SquareDegrees
    Asky
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 4 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    Description
    Value
    Unit
    Name
    number of visits shall be no less than
    The median number of visits for each place of
    the sky within the main survey area shall be at
    least
    825
    Visit
    Nv1Sum
    The ugrizy filter set is based on the filters from
    the SDSS with the addition of the y-band, These
    provide roughly uniform sampling of the optical
    spectrum from 320-1000nm.
    ugrizy
    FC
    Survey operations
    10
    Years
    SurveyTime
    1.2.2
    Schedule Survey
    ID: OCS-REQ-0007
    Last Modified: 6/23/2011
    Specification
    : The OCS shall contain an automatic scheduler, which organizes the outstanding
    observations in a way that optimizes observing time and achievement of the specified science goals.
    Discussion
    : The science goals are described in terms of science programs. The OCS Scheduler
    includes these science programs as software components, with a high level of flexibility in order to be
    capable of implement the particular cadence and distribution of each one of them. Scripting capabilities
    and adaptive parameters are also considered to cope with special purpose observations in the survey,
    and potential changes of the survey baseline definition.
    1.2.2.1
    Fully automatic scheduling
    ID: OCS-REQ-0008
    Last Modified: 6/22/2011
    Specification
    : The OCS shall be capable of schedule and operate the sequence of observations in a fully
    automated fashion during an entire night.
    Discussion
    : The OCS obtains all the relevant information from the science programs priorities, history of
    observations, environmental conditions/forecasts and subsystems states in order to build the schedule
    and conduct the survey automatically.
    Obtain candidate observations automatically
    ID: OCS-REQ-0009
    Last Modified: 6/22/2011
    Specification
    : The OCS Scheduler shall generate the list of candidate target observations for a visit in a
    fully automated fashion.
    Discussion
    : The science programs running in the OCS Scheduler will provide each one with its own list
    of targets that are allowed to be observed and are also in need of visits. This group of lists is merged by
    the scheduler to produce a single list of candidate targets for the next visit.
    Rank candidates
    ID: OCS-REQ-0010
    Last Modified: 6/24/2011
    Specification
    : The OCS Scheduler shall evaluate the list of possible candidate targets with a numerical
    rank, based on the history of observations and goals of the active science programs, in order to consider
    the benefit of all the options in the scheduling algorithm.
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 5 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    Discussion
    : Each science program contributes with its own list of ranked targets according to the
    parameters for depth, filters, time interval distribution and specific cadence requirements. The scheduler
    then takes these ranks into account when assembling the single ranked list of targets according to their
    scientific priority for the next visit.
    1.2.2.2
    Schedule Science Programs
    ID: OCS-REQ-0016
    Last Modified: 6/22/2011
    Specification
    : The OCS Scheduler shall propose target observations according to the goals and
    parameters of the science programs described in the Observatory System Specifications.
    Discussion
    : The OCS Scheduler shall select the best observation target sequence from the list of
    possible candidates, considering the benefit for the active science programs and the time cost of following
    that particular sequence.
    Keep track of each science program progress
    ID: OCS-REQ-0017
    Last Modified: 6/22/2011
    Specification
    : The OCS Scheduler shall keep track of the detailed progress of each science program.
    Discussion
    : In order to rank a particular sky field for the next visit, each science program needs to
    consider the number of visits granted for that field, the sequence of filters and the time distribution
    achieved so far, and evaluate those parameters for computing the science value for that particular field in
    the next visit opportunity.
    Observations Database
    ID: OCS-REQ-0018
    Last Modified: 6/23/2011
    Specification
    : The OCS shall keep a detailed observations database with the complete history of
    observations with their parameters and environmental conditions under which they were taken.
    Discussion
    : This observations database is utilized for ranking the future visits and also for building
    automatic and on-demand reports about the survey progress, globally and for each science program.
    1.2.2.3
    Optimize observing time
    ID: OCS-REQ-0011
    Last Modified: 6/24/2011
    Specification
    : The OCS Scheduler shall organize the sequence of observations optimizing the time
    spent collecting data.
    Discussion
    : The natural way of achieving optimum observing time is by minimizing time spent slewing
    and changing filters. This objective will sometimes go in the opposite interest of the science goals for
    some science programs, and it is the job of the OCS scheduler to make the best balance between the two
    for the time span of the survey.
    Maximize science programs
    ID: OCS-REQ-0012
    Last Modified: 6/22/2011
    Specification
    : The OCS Scheduler shall pursue the maximum goals achievement for each science
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 6 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    program.
    Discussion
    : The OCS Scheduler balances the attention given to each science program in order to obtain
    scientific profit of each visit, trying also to find targets that satisfy multiple science programs
    simultaneously.
    Minimize slew time
    ID: OCS-REQ-0013
    Last Modified: 6/22/2011
    Specification
    : The OCS Scheduler shall minimize the time spent in slewing and maximize the shutter
    open time.
    Discussion
    : The OCS Scheduler considers the cost of observing the next visit. The cost is the time
    needed from the end of the current visit to reconfigure the observatory for starting the next visit. This is
    the time to be spent slewing the telescope, slewing the dome, changing the filter and preparing the
    camera for the exposures. The accumulation of these times during the night are to be minimized by
    improving the rank of targets with shorter slews.
    Estimate slew delay for candidate observations
    ID: OCS-REQ-0014
    Last Modified: 6/22/2011
    Specification
    : The OCS Scheduler shall estimate the slew delay time from the current state of the
    observatory to the position of each possible next target, in order to consider the cost of all the options in
    the scheduling algorithm.
    Discussion
    : The slew delay is evaluated for each target in the aggregated list of candidates, and this
    time is considered along with the scientific rank in order to build the final ranked list of candidate targets
    for automatically choosing the next visit.
    1.2.2.4
    Dynamic adaptation to changing external conditions
    ID: OCS-REQ-0015
    Last Modified: 6/23/2011
    Specification
    : The OCS Scheduler shall constantly adapt the sequence of observations in real time,
    according to the external environmental conditions and the particular requirements of sky quality of the
    outstanding observations in the active science programs.
    Discussion
    : This short term adaptation must be in balance with the long term goals for the survey.
    Telemetry from the environment is key for this requirement. Weather conditions are accounted for in the
    ranking process of the targets.
    1.2.2.5
    Update Survey Parameters
    ID: OCS-REQ-0020
    Last Modified: 6/23/2011
    Specification
    : The OCS provides the interface to allow the updating of the scheduler parameters
    following the analysis of the survey progress by the survey managers.
    Discussion
    : The OCS Scheduler shall have a set of parameters that control the survey operation, such
    as active science programs, relative priorities, ranking factors, time limits, sky brightness ranges, etc.
    These parameters can be adjusted by the survey scientists and engineers after analyzing the survey
    progress reports.
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 7 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    1.2.2.6
    Schedule Calibration and Maintenance programs
    ID: OCS-REQ-0019
    Last Modified: 6/23/2011
    Specification
    : The OCS shall schedule calibration and maintenance programs, according to the baseline
    plans. These programs shall allow automatic, scripted or manual observations according to the specific
    operational needs.
    Discussion
    : During calibration and maintenance the OCS Scheduler works in a similar fashion, replacing
    the science programs by calibration or maintenance programs.
    1.2.2.7
    Image Processing Control
    ID: OCS-REQ-0021
    Last Modified: 6/22/2011
    Specification:
    The OCS shall inform the Data Management System in advance of the image acquisition
    of the needed processing related the specific image type.
    Discussion:
    This requirement ensures that the Data Management operating at the Base Facility has
    advance notice of the type of image(s) that are being acquired. This is to inform the Data Management
    system of the type of processing it needs to perform on the images as they are obtained.
    1.2.3
    Survey Lifetime
    ID: OCS-REQ-0022
    Last Modified: 6/24/2011
    Specification
    : The OCS shall support the observatory operations for the length of the 10 years survey
    (
    surveyTime
    ).
    1.2.4
    Survey Time Allocation
    ID: OCS-REQ-0023
    Last Modified: 6/14/2011
    Specification
    : The OCS scheduler shall provide the necessary capabilities and interfaces to allow the
    execution of discretional observations different from the baseline survey.
    1.2.5
    Survey Monitor
    ID: OCS-REQ-0024
    Last Modified: 11/29/2010
    Specification
    : The OCS shall constantly monitor the survey, computing metrics of the progress of each
    science program.
    Discussion
    : Reports must be automatically generated, tables and plots. The progress will be measured
    in terms of scheduled observations and similar metrics.
    1.2.6
    Survey Verification
    ID: OCS-REQ-0060
    Last Modified: 6/24/2011
    Specification
    : The OCS shall support the commissioning phase of the construction, and the science
    verification phase prior to the survey.
    1.3 Operational Requirements
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 8 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    ID: OCS-REQ-0025
    Last Modified: 11/29/2010
    Specification
    : The OCS shall support different behaviors to accommodate several operating scenarios
    depending on survey specifications and present conditions.
    1.3.1
    Operation Control
    ID: OCS-REQ-0026
    Last Modified: 11/29/2010
    Specification
    : The OCS shall be capable of commanding each subsystem of the data collection process
    of the observatory, to perform the requested observations or operational procedures.
    1.3.1.1
    Hierarchical Control
    ID: OCS-REQ-0027
    Last Modified: 6/23/2011
    Specification
    : The OCS shall be capable of commanding the subsystems in a hierarchical way. Each
    subsystem, Telescope Control System (TCS), Camera Control System (CCS) and Data Management
    System (DMS) must have a command interface for OCS, and provide its status in a detailed level.
    Discussion
    : See the ICD documents LSE-70, LSE-74, LSE-71, LSE-72 and LSE-73 for a detailed
    description of commands and status exchanges.
    1.3.2
    Observing Mode
    ID: OCS-REQ-0028
    Last Modified: 6/23/2011
    Specification
    : The OCS supports different modes of observations, according to the established
    observing plans.
    1.3.2.1
    Automatic Observation
    ID: OCS-REQ-0029
    Last Modified: 6/14/2011
    Specification
    : The OCS shall provide the means to perform observations in an automated fashion. It
    shall coordinate all the devices of the subsystems involved in an observation or sequence of observations
    in a reliable, safe and efficient way.
    1.3.2.2
    Manual Observation
    ID: OCS-REQ-0030
    Last Modified: 6/13/2011
    Specification
    : The OCS shall provide the means to perform manual observations, requested by an
    operator. It must coordinate the devices in the subsystems according to the manual instructions given by
    the user in the interfaces to perform the requested observation or sequence of observations.
    1.3.2.3
    Scripted Observation
    ID: OCS-REQ-0031
    Last Modified: 11/17/2010
    Specification:
    The OCS shall support sequencing of observations through user specified scripting of the
    sequence.
    Discussion:
    This requirements supports the needs anticipated during commissioning, establishing
    calibration sequences, and engineering and maintenance operations.
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 9 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    1.3.3
    Operation Mode
    ID: OCS-REQ-0032
    Last Modified: 11/29/2010
    Specification
    : The OCS shall be capable of being operated from different locations.
    1.3.3.1
    Local Operation
    ID: OCS-REQ-0033
    Last Modified: 6/23/2011
    Specification
    : The OCS shall provide the interfaces to operate the observatory from the control room in
    the summit.
    1.3.3.2
    Remote Operation
    ID: OCS-REQ-0034
    Last Modified: 6/23/2011
    Specification
    : The OCS shall provide the interfaces to operate the observatory from the designated
    remote locations.
    1.3.4
    User Interface
    ID: OCS-REQ-0035
    Last Modified: 6/13/2011
    Specification
    : The OCS shall provide interfaces for users to interact with its functionality.
    Discussion
    : Through the user interface, the system can be started, monitored, adjusted during
    operations and stopped, both locally and remotely.
    1.3.4.1
    Access Control
    ID: OCS-REQ-0036
    Last Modified: 11/29/2010
    Specification
    : The OCS shall control the access to the user interfaces with an authentication
    mechanism.
    1.3.4.2
    Displays
    ID: OCS-REQ-0037
    Last Modified: 11/29/2010
    Specification
    : The OCS shall provide displays of system-wide state information.
    1.3.4.3
    GUI
    ID: OCS-REQ-0038
    Last Modified: 6/23/2011
    Specification
    : The OCS shall provide graphical and command line interfaces to facilitate the observatory
    operations.
    1.3.5
    Change of subsystem state without failure
    ID: OCS-REQ-0059
    Last Modified: 6/23/2011
    Specification
    : The OCS shall not fail if a subsystem unexpectedly changes state, does not respond or
    otherwise fails to operate as required.
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 10 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    Discussion
    : The OCS will issue messages to the other subsystems to notify of this change of state or
    failure in order to protect other subsystems from such a condition.
    1.3.6
    Graceful degradation
    ID: OCS-REQ-0039
    Last Modified: 6/23/2011
    Specification
    : The OCS shall enable the observatory to continue the survey in a gracefully degraded
    mode in case of subsystems failures that still allow the acquisition of useful data.
    Discussion
    : When a device in a subsystem is in failure, the OCS disables that device and takes the
    needed actions in the scheduling process in order to use the new limited range of observations that are
    still useful for the science goals.
    1.3.7
    Safety
    ID: OCS-REQ-0040
    Last Modified: 6/24/2011
    Specification
    : The OCS shall follow the safety policies established by the Observatory System
    Specifications (OSS-REQ-0098).
    Discussion
    : The status of the safety system must be monitored by the OCS. Unsafe conditions must be
    reported directly to the observatory operators as well as logged by the OCS. No part of the OCS is
    allowed to be part of or interfere with, any observatory safety systems.
    1.3.7.1
    Interlock System
    ID: OCS-REQ-0041
    Last Modified: 6/22/2011
    Specification
    : The OCS shall follow the state of an external interlock system to abide for a safe operating
    environment.
    1.3.7.2
    Safety Procedures
    ID: OCS-REQ-0043
    Last Modified: 6/22/2011
    Specification
    : The OCS shall enforce the application of safety procedures in the observatory operations.
    1.4 Observatory Services
    ID: OCS-REQ-0044
    Last Modified: 6/23/2011
    Specification
    : The OCS provides services of common use observatory-wide, in order to optimize the use
    of information technologies.
    1.4.1
    Configuration Database
    ID: OCS-REQ-0045
    Last Modified: 6/24/2011
    Specification
    : The Configuration Database shall manage the different configuration parameters needed
    for each subsystem, for the different observing modes.
    Discussion:
    The Configuration Database maintains also the latest configuration utilized during
    operations, that can be utilized for rapid restoration of service, in case of failure.
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 11 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    1.4.2
    Engineering Facility Database
    ID: OCS-REQ-0046
    Last Modified: 6/22/2011
    Specification
    : The OCS shall capture, organize and store system-wide, time tagged state information to
    make it available for monitoring, evaluation and calibration processes.
    Discussion
    : This section will implement the requirements on the functionality and performance of the
    Engineering and Facility Database (EFD) as it relates to the Telescope, Camera, Data Management and
    Calibration operations. This includes (but is not limited to) telemetry ingestion, replication of the EFD at
    Base and Archive sites, support of queries and instantiation of the EFD during the development phase of
    the subsystems.
    This telemetry and observatory condition information will be distributed to support both local and remote
    operations in an efficient manner.
    1.4.2.1
    Availability of EFD contents
    ID: OCS-REQ-0047
    Last Modified: 6/23/2011
    Specification
    : All EFD contents shall be available for queries not impacting real time subsystems
    activities.
    Discussion
    : A complex query like "raft 13 temperatures for past 2 years" may span EFD instances at
    mountain, base, and archive and/or access centers. Such access must be user transparent. The
    performance of a query processing is subject to a quality of service assignment.
    1.4.2.2
    Persistence of Telemetry
    ID: OCS-REQ-0048
    Last Modified: 6/24/2011
    Specification
    : The EFD shall persist all published observatory telemetry generated by the OCS,
    telescope, camera and data management subsystems.
    Discussion
    : In particular, up to the defined limits in OSS -REQ-0311 and replicated here, all published
    telemetry is captured reliably by the EFD, permanently.
    EFD_OCSparameters
    ID:
    Last Modified: 6/24/2011
    Description
    Value
    Unit
    Name
    Long-term mean ingest rate to the Engineering
    and Facilities Database required to be supported.
    6.5
    Mbit/sec
    EFD_AvgRate
    The minimum supported daily data volume of the
    engineering facility data base.
    30
    GBytes
    EFD_DayStore
    Long-term mean ingest rate to the Engineering
    and Facilities Database of non-science images
    required to be supported.
    15.4
    Mbit/sec
    Blob_AvgRate
    Maximum ingest rate to the Engineering and
    Facilities Database of non-science images
    required to be supported.
    21.9
    Mbit/sec
    NonScience_MaxRate
    1.4.3
    Middleware Communications
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 12 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    ID: OCS-REQ-0049
    Last Modified: 6/22/2011
    Specification
    : The OCS shall implement a middleware communications layer to allow the commanding
    and telemetry capture to all subsystems.
    Discussion
    : The baseline architecture of this middleware is based on the publish/subscribe protocol, as
    defined by the Data Distribution Service (DDS) standard.The communications backbone runs on top of
    the Observatory network infrastructure.
    1.4.4
    System Monitor
    ID: OCS-REQ-0050
    Last Modified: 6/22/2011
    Specification
    : The OCS shall provide the means for a continuous system monitoring, during night time
    as well as day time, giving support for the science, calibration and engineering observations, status and
    activities, also facilitating the hand over of the system between users in different work shifts.
    Discussion
    : One of the important monitoring functions is a comprehensive handling of events
    incorporated into the telemetry stream, logged as a component of the EFD.
    2 OCS Maintenance Requirements
    ID: OCS-REQ-0051
    Last Modified: 11/29/2010
    Specification
    : The OCS shall support the maintenance activities of the observatory, capturing and
    storing telemetry, coordinating routine maintenance operations and providing interfaces to the users to
    evaluate and perform maintenance jobs.
    2.1 Analysis
    ID: OCS-REQ-0052
    Last Modified: 6/23/2011
    Specification
    : The OCS shall provide tools for the analysis of telemetry and state information in order to
    optimize the system and to measure performance trends over long periods.
    Discussion
    : The analysis tool set is intended to be flexible and expandable, to cope with specific
    demands from the subsystems. The subsystems may develop extensions using the infrastructure
    provided by the tool like EFD access and report and graphics generation.
    2.2 Maintenance Log
    ID: OCS-REQ-0053
    Last Modified: 6/23/2011
    Specification
    : The OCS shall maintain a log of all the maintenance activities. The OCS shall provide an
    interface to manually generate the complimentary maintenance information that it is not possible to obtain
    through the telemetry. This interface shall also allow to obtain and analyze the information about the
    maintenance activities performed in every subsystem.
    2.3 Maintenance Planning
    ID: OCS-REQ-0054
    Last Modified: 6/23/2011
    Specification
    : The OCS shall support the planning of maintenance activities to perform preventive
    maintenance in order to achieve the reliability goals of the system.
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 13 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    Discussion
    : The outcome of the planning activities will be a report with the proposed job(s) to be
    performed at the observatory.
    2.4 System Maintenance
    ID: OCS-REQ-0055
    Last Modified: 6/23/2011
    Specification
    : The OCS shall provide the means for performing and supporting maintenance activities in
    the observatory. The OCS shall provide the tools to support the scheduled maintenance jobs originated
    as a result of the planning activities.
    Discussion
    : The support comprises the coordination of the subsystems in activities like, getting a new
    pointing model set of parameters in the TCS with the computations from the DM.
    3 OCS Performance Requirements
    ID: OCS-REQ-0056
    Last Modified: 6/23/2011
    Specification
    : The OCS contributes to the performance of the observatory, scheduling the survey with
    the goal of maximize the specified science observations, and coordinating the subsystems efficiently in all
    the automatic observation modes.
    3.1 Downtime
    ID: OCS-REQ-0057
    Last Modified: 6/23/2011
    Specification
    : The OCS software and hardware reliability performance shall abide to the
    unplannedDownTime
    of unscheduled downtime assigned to the observatory.
    Discussion
    : The parameter
    unplannedDownTime
    is defined in OSS_REQ-0082 as 21 days annually.
    The OCS will track this performance parameter during the survey lifetime and report it using the
    maintenance tools.
    3.1.1
    unplannedDownTime
    Last Modified: 6/23/2011
    Description
    Value
    Unit
    Name
    The allowed time the system can be down for
    unplanned events is
    21
    Days
    unplannedDownTime
    3.2 Null Overhead
    ID: OCS-REQ-0058
    Last Modified: 6/23/2011
    Specification
    : The OCS control and scheduling activities shall not add overhead time to the operation of
    the observatory. The commanding and telemetry traffic delays shall be negligible in comparison to the
    control time constants of the subsystems.
    Discussion
    : All the eventual time consuming OCS activities (such as scheduling computations) will be
    performed in advance to the actual observations and in parallel to the already defined sequence of
    activities.
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 14 of 15

    Large Synoptic Survey Telescope
    Observatory Control System Requirements
    LSE-62
    The contents of this document will be subject to configuration control and may not be changed, altered, or
    their provisions waived without prior approval of the LSST Change Control Board.
    2011-06-24
    Page 15 of 15
    3.3 Communications Performance
    ID: OCS-REQ-0061
    Last Modified: 6/24/2011
    Specification
    : The OCS middleware communications performance shall comply with a latency of less
    than
    ocsMsgLatency
    , a throughput of at least
    ocsMsgRate
    , and a data persistence of at least
    ocsMsgPersistence
    .
    3.3.1
    communicationsPerformance
    Last Modified: 6/23/2011
    Description
    Value
    Unit
    Name
    The message transmission in the OCS
    middleware has a latency of less than
    300e-6
    Seconds
    ocsMsgLatency
    The OCS middleware has the capacity of
    handling messages at a rate of at least
    50e3
    Hz
    ocsMsgRate
    The message persistence of a particular
    parameter in the OCS middleware is of at least
    2 messages
    history
    ocsMsgPersistence

    Back to top