2.2. Level 3 SWCS Requirements#

The Level 3 SWCS Requirements Document [Mait13] is broadly divided into Functional & Performance Requirements, and General Requirements, as prescribed by Systems Engineering. Functional & Performance Requirements address telescope operations (e.g., pointing, guiding, calibration, and thermal control), observations, and observatory operations (e.g., data management, networking, and common services). In comparison, General Requirements address standards, environment, health and safety, power services, maintenance, reliability, and documentation of the observatory systems.

Before delving more specifically into Level 3 SWCS requirements, the following Table presents an overview of the key System Level Requirements and their flow-down to the SWCS:

Table 2.1 Principle Level 2 to Level 3 Requirements that Impact SWCS Design Considerations#

Level 2 Requirements Summary

Level 3 Requirements Flowdown Summary

Lifetime - Design for a 50-year lifetime, assuming routine maintenance and periodic upgrades of components and subsystems.

Communication Standards - Define a set of physical communication protocols.

Electronics Standards – Comply with the electronics standards specifications per GMT-SE-REF-00191.

Permanent Storage – Implement permanent data storage and backup system at the observatory.

Critical Spares – Provide spares for critical subsystem and instrument components as defined in the GMT Critical Spares Document (GMT-SE-DOC-00277).

Efficiency - Optimize on-sky observing efficiency.

Efficient Operations - Identify and define sequences for instruments, telescope, and science, operations to optimize on-sky observing efficiency and comply with GMT Efficiency Budget (GMT-SE-REF-00593).

User Command Sequencing - Provide capability to arrange commands in a way that allows users to automate the execution of complex operations.

Operation Modes - Enable classical, queue, interrupt, and remote observer modes.

Operation Modes – Provide classical, queue, interrupt, and remote observer operation modes.

Scheduling and Planning - Provide software for advanced planning, scheduling, and management of observing programs, observatory workflows, and tasks.

Observing Modes – Provide natural seeing, NGSAO, LTAO, and GLAO observing capabilities.

Observing Modes – Provide capability to operate the telescope in natural seeing, GLAO, NGSAO, and LTAO observing modes.

Mode Switching – Provide the capability to switch from one observing mode to another.

Observing Conditions Monitoring – Provide the capability to monitor the required observing conditions.

Incomplete Segmentation – Provide ability to operate with incomplete segmentation.

Direct Gregorian (DG) Ports Folded Port (FP) Stations, and Gravity Invariant Stations (GIS) - Provide standardized locations in the Gregorian Instrument Rotator (GIR), on the top surface of the GIR, and on the Azimuth Structure, for mounting, DG, FP, and GIS, Science Instruments, respectively.

Focal Stations – Provide the capability to operate the telescope using any of the eight focal stations or future expansion ports.

Configuration – Provide the capability to switch from one telescope optical configuration to another in an automated way for active instruments.

Instruments – Provide capability to automate switching of active instruments, initiated and monitored by the operator.

Pointing Models - Provide the ability to store and switch between different pointing models for all the focal stations.

FP Pupil Stability - Maintain the position of the exit pupil at the FP focus to less than or equal to 0.25% peak to valley of the pupil diameter.

Active Correction - Actively control the optical system to obtain the best image quality performance.

Pointing Accuracy - Provide: blind pointing with error less than 5 arcsec rms over the full range of telescope motion after initialization; relative pointing to a guide star with accuracy better than 0.2 arcsec at the center of the science field for DG science instruments under natural seeing.

Pointing Accuracy - Provide capability to: blind point with accuracies that comply with error budgets in document GMT-SE-REF-00477; point relative to a guide star under natural seeing with accuracies that comply with error budgets in document GMT-SE- REF-00477.

Differential Flexure Correction - Provide capability to correct differential flexure between the AGWS and/or AO Wavefront Sensors and the Science Instruments, using internal guide sensors provided by the Science Instruments, so as to comply with GMT Pointing Budget (GMT-SE-REF-00477).

Automation of Start-up/ Shutdown – provide automated start-up / shutdown sequences, procedures, and processes that are initiated, monitored, and controlled by the operator.

Automated Start-up/Shutdown Procedures - Provide the capability to execute start-up and shutdown processes that are initiated and monitored under operator control.

Standard State Machine – The control subsystem components shall implement a SWCS standard state machine.

Operation Support – Provide software tools to support proposal preparation, program definition, execution planning, execution, and quality assessment.

Astronomers’ Tools – Provide software tools to assist astronomers in the proposal process, observing program definition, and execution planning.

Observatory Operations – Provide software tools to schedule and manage observatory workflows and tasks, and to execute observing programs.

Quality Assessment – Provide software tools to assess the validity of observation data products.

On-line Assistance – Provide centralized on-line tools to inform, search, and execute user commands, and software components.

Observing Support - Provide software, with integrated and consistent user interfaces, to support observing and operation modes.

Condition Monitoring - Provide capabilities to monitor the required observing conditions.

Automated Reconfiguration – Provide capability to switch from one telescope optical configuration and instrument to another in an automated way for any active instruments.

Graphical User Interface - Provide an integrated and consistent graphical user interface.

Feature Discovery/Navigation - Provide capability to discover, navigate, and access efficiently any feature provided by any software component.

Centralized Operation - Critical systems for operations shall be controlled from centralized operator workstations.

Centralized Control Functions – Provide central control capabilities for every control subsystem.

Control Room - The GMT observatory shall be operated centrally from the control room.

Operators - Design for operation by telescope operators, instrument specialists, and AO specialists.

Data Archive and Access - Provide data archive system for collecting, storing, retrieving, and accessing all raw science and engineering data acquired during observations, including relevant metadata.

Science and Engineering data access - provide the capability to uniformly store, query, retrieve, and access: all data (raw and processed) during an observation, engineering data from all subsystems, system logs and documentation, electrical and electronic schematics.

On-Line Documentation – Provide users with online help, guides, and manuals for all equipment and facility instrumentation used during routine operations, in a contextual manner.

System Health - Provide continuous performance, status, and system health monitoring.

System Health Assessment - Provide capability to assess the overall health of the system.

Engineering Data System – Provide engineering data system to monitor the health and performance of all subsystems critical to the functioning of the observatory.

Telemetry - provide capability to sample, display, and correlate any signal with the resolution and frequency required to characterize the behavior of the signal.

Log System - provide a method to detect, store, and notify the occurrence of relevant operation events.

Alarm System – provide the capability to manage alarm conditions.

Code Compliance and Design Safety - Design and construct in accordance with building, occupational, and electrical safety codes defined in GMT Compliance to Regulations, Codes and Standards (GMT-SE-REF-00229); adopt design safety practices to reduce risk to personnel and equipment.

Overall Safety - Comply with GMT standards and procedures to insure the safety of the GMT facility, equipment, and personnel at all times (GMT-SE-REF- 00229).

Interlock Safety System (ISS) – Interface with the ISS to ensure the safe operation of the system.

Enhancing Safety via Software – Provide software to enhance the safety and integrity of the System.

Safety Limits Redundancy – Include redundant software limits on all systems with moving parts that present an over-travel hazard risk.

Non-interference of Manual Override – The SWCS shall not interfere with the protected manual overrides on interlocks.

Time-outs – Critical subsystems shall have built-in time-outs to ensure correct operation in case of central control failure.

Standards - SWCS defines Software and Controls (GMT-SWC-REF-00029), and complies with Laser Safety (GMT-SE-REF-00229) Standards.

Architecture - Establish architecture for instrument software and control subsystems.

Software/Hardware Standards – Establish a set of Software/Hardware standards (GMT-SWC-REF-00029) for the project.

Communication Standards – Define a set of physical communication protocols.

Electronics Standards – Comply with the electronics standards specifications per GMT-SE-REF-00191.

The subsections below present the Level 3 SWCS Requirements in more detail. Functional, Performance and General Requirements are further subdivided into other sub-categories, as summarized in subsections below.