This PDF file contains the front matter associated with SPIE Proceedings Volume 11450, including the Title Page, Copyright information and Table of Contents.

We present an end-to-end model of the signal-chain of the correlator and beamformer of the Square Kilometre Array Phase 1 Mid telescope. The objective of this model is to determine whether the proposed signal processing architecture can meet the SKA’s stringent requirements on signal quality. The model consists of two parts: 1) the “Reference” model, and 2) the “Realizable” model. Both are implemented in MATLAB. Both the reference and realizable models are implemented with double-precision floating point arithmetic, however, the realizable model considers quantized data and coefficients for the signal processing algorithms. The time-varying delay due to the rotation of the Earth and the synthesized celestial source is modeled in the signal generator. The signal generator also supports the modeling of signals sampled according to the Sample Clock Frequency Offset method. Both reference and realizable models utilize a two stage delay correction process with integer delay correction and resampling with a fractional-delay filter-bank. Combinations of oversampled polyphase filter-banks, critically-sampled polyphase filter-banks, digital down-convertors, threshold-based RFI detectors, phasedelay beamformers and complex cross-multiplier accumulators are used to model the continuum/spectral-line imaging, zoom-imaging, pulsar-search-beamforming, pulsar-timing-beamforming, VLBI-beamforming and VLBI visibilities to parameter evaluation for calibration. This model has been used to verify that the proposed delay correction method is sufficient to achieve the required sensitivity. Also, this provided evidence that the phase-delay beamforming method can be successfully used for pulsar-timing beamforming. The study of the degradation of the signal quality in response to various RFI scenarios, which are expected on the telescope site, has also conducted and published.

In order to validate the design of the Low Frequency Aperture Array (LFAA) for the Square Kilometer Array-Low telescope (SKA-Low), a complete model has been developed. The model includes 1) a sky simulator, producing a realistic sky signal with predefined spectrum and correlation properties, plus correlated and uncorrelated Radio Frequency Interference (RFI) signals; 2) a nonlinear model of the analog receiver chain; 3) a close representation of the digital signal processing algorithms for channelization, calibration and beamforming. The model describes correctly all the aspects of the LFAA station beamformer, generating the expected signal for up to 256 antennas and reproduces the processing required to combine them into a station signal. It is an useful tool to analyze variants of the proposed signal processing algorithms or to highlight possible problems. The resulting simulated output can be used to analyse the beamforming performance and as an input for a correlator simulation model in a telescope end-to-end simulation.

The accurate simulation of water vapour radiometers (WVRs) prior to prototyping and laboratory testing has been a shortcoming in the state-of-the-art, despite the benefits to system development time and cost reduction. This paper presents a new approach to simulate and analyse the performance of different WVR topology designs by using a commercial RF system simulator, AWR’s Visual System Simulator (VSS). Several WVR topology designs are evaluated, using component data from vendors or state-of-the-art published literature. The results indicate good correspondence with prior measurement results, but also enables the retrieval of performance metrics (such as temperature sensitivity) previously unavailable as a simulation data product.

The size and complexity of ground-based astronomy instrumentation is continuously increasing in order to make most efficient use of the existing and new facilities. The logic of this trend is clear, since the high cost of building and maintaining telescopes leads to high demand for their use, maximising the science output is essential. Instrument multiplex and operational modes are therefore ever-increasing. In highly complex instruments, it can be difficult to interpret the meaning of the term “failure” since the loss of individual channels or modes is not the same as a total loss of science capability. In this paper we explore the relationship between the instrument reliability and the delivered science. We also discuss the need to incorporate a good understanding of the reliability in the instrument design. We consider the difference between the inherent availability of the instrument, the operational availability and the scientific output. At the UKATC we have developed a process and set of tools to analyse an instrument design to determine both the inherent and operational availability using a combination of Failure Mode, Effect and Criticality Analysis (FMECA), Reliability Diagrams, and Fault Tree Analysis. These can then be considered in terms of the instrument productivity to determine strategies for redundancy, maintenance and repair. We also review the state of reliability analysis within the ground-based community and compare it with the requirements for space astronomical instrumentation. The methodology and tools developed are intended to be compliant with the requirements for space products.

The Data Management System (DMS), part of the Science Operations Center (SOC) for the Nancy Grace Roman Space Telescope is focusing on creating new and innovative methods for scientist to interact with the voluminous data Roman is expected to produce. This talk will focus on the intersection of traditional project management and agile development methodologies to satisfy both NASA’s risk mitigation and reporting needs for a “Class A” mission and the development team’s needs to explore and develop innovation solutions for data ingest, processing, and distribution. The discussion will include how modern agile methods and tools are being used to automate traditional project management needs.

The Data Management (DM) subsystem of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) is responsible for creating the software, services, and systems that will be used to produce science ready data products. The software, currently under development, is heterogeneous, comprising both C++ and Python components, and is designed to facilitate both the processing of the observatory images and to enable value-added contributions from the broader scientific community. Verification and validation of these software products, services, and systems is an essential yet time-consuming task. In this paper, we present the tooling and procedures developed to ensure a systematic approach to the production of documentation for verification and validation. By adopting a systematic approach, we guarantee full traceability to system requirements, integration with the project’s Systems Engineering model, and substantially reduce the time required for the whole process.

The availability requirement for the SKA telescopes will have a major impact on the design, capital and operating costs. The design-for-reliability, maintainability, maintenance planning and performance expectations should be well balanced. Engineering analysis indicates that the SKA telescopes should have an inherent availability of 99% and both telescopes are required to have an operational availability of at least 95%. This paper discusses the availability and support challenges of building and operating two telescopes in Australia and South Africa. It describes the approach to the critical design review of the system, with a special focus on simulation modeling and sensitivity analysis. It also discusses the use of failure data from the precursor telescopes and gives technical insight into the development of a digital twin for decision making. .

I describe the plans, flows, key facilities, test beds, pathfinders, simulators, and ground support equipment that could be used to fully integrate, functionally test, and qualify the Origins Space Telescope (Origins). The Origins observatory consists of the spacecraft bus module and the cryogenic payload module, which comprises the telescope and three science instruments. The telescope is a three-mirror anastigmat and is composed of four mirrors: three with optical power (the elliptical primary, hyperbolic secondary, and elliptical tertiary mirrors) and a flat field-steering mirror. The three science instruments spanning the wavelength range 2.8 to 588 μm provide the powerful new spectroscopic and imaging capabilities required to achieve the scientific objectives. The Origins Survey Spectrometer uses six gratings in parallel to take multibeam spectra simultaneously across the 25- to 588-μm window through long slits enabling deep three dimensional extragalactic surveys. The far-IR imager/polarimeter provides imaging and polarimetric measurement capabilities at 50 and 250 μm. Its fast mapping enables rapid follow-up of transient or variable sources and efficient monitoring campaigns. The mid-infrared spectrometer simultaneously provides spectroscopy over 2.8 to 20 μm with exquisite stability and precision (<5 ppm between 2.8 and 10 μm, <20 ppm between 11 to 20 μm). All the instruments are delivered for integration and test fully qualified and calibrated. The integration and test program implemented at each level of assembly is discussed as well as the separation of thermal vacuum testing between the hot and cold zones of the observatory.

In the advanced design, construction, and commissioning phases of GMTO project, the critical role of systems engineering is tracking and managing expected observatory performance and ensuring that the scientific goals of the Giant Magellan Telescope (GMT) are met. GMTO’s approach to this role is defining Key Performance Parameters (KPPs) to measure technical performance. A set of KPPs have been established to assess the performance of the telescope through construction and Assembly, Integration, Verification, and Commissioning (AIVC). Each KPP has a threshold value representing the minimum acceptable performance, and an objective value representing the desired operational performance. KPPs are used to prioritize maturation plans for technologies and novel system-level design strategies. The KPPs directly characterize the performance of the telescope by ensuring focal plane (image), exit pupil (wavefront) and light collecting capabilities of the telescope. The paper demonstrates that the chosen KPPs properly represent key science capabilities, as image size, sensitivity, photometric, and astrometric accuracy. It is also shown how detailed error budgets link the KPPs to component technical specifications that in turn are closely monitored by simulations. Integrated modeling is crucial for the performance-based systems engineering approach of defining and then evaluating the objective and threshold levels for the KPPs. As described in other GMTO paper at this conference, contributions from individual subsystems and components are modeled to determine their effect on system performance. We describe how GMTO has implemented KPPs and is now using them to guide and coordinate technical development.

This paper presents the state-of-the-art techniques employed in aerothermal modeling to respond to the current observatory design challenges, and in particular those of the US Extremely Large Telescope Program (USELTP). It reviews the various aerothermal simulation techniques, the synergy between modeling outputs and observatory integrating modeling and recent applications. Finally, it addresses planned improvements, the development of new ideas, attacking new challenges and how it all ties to the AIAA “CFD 2030 Vision”.

System engineering at GMTO is using a comprehensive integrated model that integrates seamlessly, in a unified framework, finite element, optics, and control models. A computational fluid dynamics (CFD) model of the observatory is also used to estimate dome seeing, wind jitter, structural thermal deformations, and observatorywide design optimization. The GMT integrated modeling group realizes various studies for different subsystems of the project that provides the basis for the subsystem level design trades. It also assists system engineering by performing top-down and bottom-up requirements verification, error budget derivation, and operational strategies optimization. Integrated modeling will also support system engineering during the assembly, integration, verification, and commissioning phase of the project. For example, system engineering relies on the integrated model to estimate the key performance parameters (KPP) of the project. The KPP are performance metrics that will be used to validate the completion of the observatory and to confirm its readiness with respect to the start of science observation. In the paper, we give a system-level overview of the integrated model, including a description of each sub-model and of the framework that binds them together. The paper also describes how system engineering is using the integrated model for the derivation of the error budgets and of the top-down requirements flowing down from the science requirements to the lower level of subsystem engineering requirements; and how as the design of the subsystems progress, integrated modeling is then used to validate, bottom-up, the same requirements from subsystem engineering requirements back up to the science requirements with respect to the observatory performance metrics.

ESO took a systematic approach at earliest phases of the ELT programme to address different aspects of vibration at telescope, from modelling, error budgeting, requirement specifications, to envisaging verification and mitigation methods. Recent activities focused on characterisation of the vibrational forces generated by typical equipment in the observatory. Those measured forces combined with the models of the telescope are used to verify various subsystems specification as well as to verify the overall system performance. In this paper, an approach used for vibration force measurements together with some examples of the characterised sources are discussed. The verification of performance/requirements at telescope system/subsystem is performed using these measured data.

ULTIMATE-Subaru is a next large facility instrument project at Subaru telescope. We will develop a 14x14 sq. arcmin wide-field near-infrared (NIR) imager and a multi-object spectrograph with the aid of a ground- layer adaptive optics system (GLAO), which will uniformly improve the seeing by a factor of 2 over a wide field of view up to ~20 arcmin in diameter. We have developed system modeling of the GLAO and wide-field NIR instruments to define the system level requirements flow down from science cases and derive the system performance budgets based on the GLAO end-to-end numerical simulation and optical system models of the telescope and wide-field NIR science instruments. In this paper, we describe the system performance modeling of ULTIMATE-Subaru and present an overview of the requirements flow down.

The Extremely Large Telescope (ELT) is the largest optical and infrared telescope being planned and constructed at the present time. Its resolution overtakes current limits of performance for large telescopes, as well as current levels for all the engineering fields involved in the design and realization of the telescope. The design of the ELT Main Structure (MS) is supported by exhaustive performance and resistance analyses, which have now largely been completed. A Finite Element Model (FEM) of the MS has been created to analyse the telescope behaviour against all the significant actions, among which gravity, wind, seism, thermal, manufacturing and alignment tolerances can be mentioned. The model is characterized by several millions of degrees of freedom and it includes the Telescope pier and foundation, as well as the seismic isolation system and the natural soil. A detailed Computational Fluid Dynamic (CFD) model has been produced and validated with the support of a wind tunnel test campaign. Several cases of telescope orientation and Altitude configuration, wind velocities and turbulence intensities have been analysed. A State Space model has been set-up to perform the Servo analysis of the Azimuth and Altitude axes. Frictions and motor disturbances, encoders quantization, loops sampling and latencies have been considered, to assess tracking, slewing and offsetting performances and to assess the structural behaviour and the wind rejection. Finally, a comprehensive mathematical model of Dome, MS and soil has been set-up to perform the vibration analysis of the whole observatory. The purpose of this paper is to provide an overview of the generated models, the performed analyses and the most significant obtained results.

The primary mirror of the Giant Magellan Telescope (GMT) consists of seven 8.4-meter diameter borosilicate segments. While this design has optical advantages, the unmitigated seismic risk is significant. Recently added design features meet this challenge. A 2D seismic isolation system decouples the telescope from horizontal ground motion and dampers at the interface with the primary mirror segments attenuate their motion. A detailed analysis framework has been developed to justify and refine the design. Discrete analyses, in which the models are exercised at discrete seismic intensity levels, are used to generate requirements throughout the telescope via a seismic response spectrum approach. Risk-based analyses utilize a broad characterization of uncertainty to assess probability of survival of the most critical components. These tools support a general design strategy that effectively trades the cost of designing and constructing the telescope against the seismic risk.

We present our investigation into the impact of wavefront errors on high accuracy astrometry using Fourier Optics. MICADO, the upcoming near-IR imaging instrument for the Extremely Large Telescope, will offer capabilities for relative astrometry with an accuracy of 50 micro arcseconds (mas). Due to the large size of the point spread function (PSF) compared to the astrometric requirement, the detailed shape and position of the PSF on the detector must be well understood. Furthermore, because the atmospheric dispersion corrector of MICADO is a moving component within an otherwise mostly static instrument, it might not be sufficient to perform a simple pre-observation calibration. Therefore, we have built a Fourier Optics framework, allowing us to evaluate the small changes in the centroid position of the PSF as a function of wavefront error. For a complete evaluation, we model both the low order surface form errors, using Zernike polynomials, and the mid- and high-spatial frequencies, using Power Spectral Density analysis. The described work will then make it possible, performing full diffractive beam propagation, to assess the expected astrometric performance of MICADO.

Primary mirror segment shape correction via Warping Harness (WH) control adjustment is key to obtaining the required image performance of the Thirty Meter Telescope (TMT). We analyzed two separate experimental activities to better predict the segment WH performance. First, we took measurements of WH influence functions and Singular Value Decomposition (SVD) modes on a prototype TMT segment and compared these to model predictions. Second, we applied the TMT control algorithm on-sky at the Keck Observatory during their segment exchange and warping activities. We then used these measurements to improve our WH control simulations to include the observed effects. Altogether, the prototype segment measurements, on-sky TMT control algorithm measurements, and detailed simulation helped to better predict segment correction performance for TMT.

Collectively, the astronomical community is responsible for building phenomenal, cutting edge observatories and cameras; machines that have revolutionized humankind’s understanding of the Universe. It is the nature of these complex projects to be inherently difficult to fully scope a-priori, leading to cost and schedule overruns. While we should not expect to eliminate this risk entirely, more can be done to manage change while executing our programs. By creating a culture of baseline control, the entire team can be enlisted to help identify and mitigate programmatic impacts in the best manner for the system. Practical baseline management habits and practices will be presented, with an emphasis on how to implement a robust change control process and culture amongst your program team.

Parametric cost models can be used by designers and project managers to compare cost between major architectural cost drivers and allow high-level design trades; enable cost-benefit analysis for technology development investment; and, provide a basis for estimating total project cost between related concepts. The NASA Marshall Space Flight Center has developed a 5-parameter first-article optical telescope assembly cost model OTA$ (FY17) = $20M x 30 ^(S/G) x D ^(1.7) x λ (-0.5) x T ^(-0.25) x e ^{(-0.028) (Y-1960)} Where S/G = 1 for space and 0 for ground telescopes, D = diameter, λ = diffraction limited wavelength, T = operating temperature and Y = year of development. The model explains 92% (Adjusted R2) of the cost variation in a database of 47 total ground and space telescope assemblies (OTA). The MSFC model estimates the most likely cost for only the OTA. Where an OTA is defined as the subsystem which collects electromagnetic radiation and focuses it (focal) or concentrates it (afocal) into the science instruments. An OTA consists of the primary mirror, secondary mirror, auxiliary optics and support structure (such as optical bench or truss structure, primary support structure, secondary support structure or spiders, straylight baffles, mechanisms for adjusting the optical components, electronics or power systems for operating these mechanisms, etc.). Finally, duplication only reduces cost for the manufacture of identical systems (i.e. multiple aperture sparse arrays or interferometers). And, while duplication does reduce the cost of manufacturing the mirrors of segmented primary mirror, this cost savings does not appear to manifest itself in the final primary mirror assembly (presumably because the structure for a segmented mirror is more complicated than for a monolithic mirror).

The Cherenkov Telescope Array (CTA) is the next-generation atmospheric Cherenkov gamma-ray observatory. CTA will be deployed as two installations, one in the Northern and the other in the Southern Hemisphere, containing telescopes of three different sizes, for covering different energy domains, with varying designs. The CTA Observatory (CTAO) is building a complex and distributed software system for the efficient operation of the arrays and the management and scientific exploitation of the CTA data. The largest fraction of the construction budget of CTA will come as in-kind contributions (IKCs) from CTA Shareholders (participating countries and research centres), with the prominent IKC example of the telescopes themselves. Most of the effort to build the CTA software will be provided by IKCs as well, with CTAO personnel managing the coordination between partners, ensuring common development practices, and facilitating that the requirements, integration, quality level, and deadlines are properly met. This contribution presents the management plan of one of the main CTA software work packages, the Array Control and Data Acquisition (ACADA). The ACADA software will be responsible for the coordination of the control and data acquisition of telescopes, as well as many auxiliary instruments. The ACADA team will be composed of about 30 developers distributed in eight IKC teams, CTAO personnel, and company contracts. The contribution shows how model-driven software architecture practices are essential for the management of such a distributed team, which is predominantly composed of IKCs

The SAAO observing station near Sutherland, Northern Cape Province (NCP), South Africa, is among observatories with the darkest skies in the world. It is home to many national and international optical and IR telescopes, including SALT. The NCP is declared as Astronomy Advantage Area, and therefore regulated under the Astronomy Geographic Advantage Act of 2007, which empowers the Department of Science and Innovation minister to regulate activities that pose a threat to optical and/or radio astronomy within the declared areas. In May 2019, the Sutherland Central Astronomy Advantage Area (SCAAA) protection regulations aimed at protecting optical astronomy and related endeavours at SAAO against activities negatively impacting on astronomy within the SCAAA (75 km radius from SALT in the NCP), were promulgated. We discuss these regulations, including monitoring of light pollution and other activities that may have negative impact on astronomy at SAAO, regulatory implementation and compliance, as well as current and potential challenges, and lessons learned so far. The night sky brightness measurements collected over the past five years with the All Sky Transmission MONitors (ASTMONs) at Sutherland are presented for the first time, and they indicate that the quality of the night sky at SAAO has not changed for the worst going as far back as the 1980s. The current average sky brightness measurements from the ASTMONs are consistent with historical night sky brightness measurements collected with the SAAO telescopes over the past 40 years. The results also confirm that Sutherland is globally a very dark observatory site.

The National Research Council Canada Herzberg Astronomy and Astrophysics Research Centre (NRC/HAA) is one of a few astrophysics research centers in the world that embodies science, technology development, and data archiving and analysis across ultraviolet, optical, infrared, and radio wavelengths. Our research centre is involved in both short and long term instrumentation and observatory development projects. We conduct significant strategic R&D in-house and also in collaboration with external organizations. In order to guide our future research and development, we have implemented roadmaps that connect Canadian science strategic directions to current and future observing capabilities, and that identify needed technology development to achieve our goals. In this paper we present the process of developing these roadmaps, and describe the science and technology directions that we are pursuing as a result of this strategic planning.

Large or complex systems tend to be challenging when it comes to managing their project and construction while keeping the costs at an acceptable level. Systems Engineering aims not only to reduce that difficulty by systematically owing down the top-level user needs to the bottom level parts specification, but also by describing the full aspects of its lifecycle. Moreover, together with Systems Management, they aid the completion of intricated projects, such as professional telescopes. This paper shows how Systems Engineering and Systems Management are helping the construction of one important instrument for the Giant Magellan Telescope: MANIFEST, which is a robotic fiber-optic positioning system that improves the capabilities of other instruments in the telescope. It can increase and even split their field of view into two or more instruments. Its Operations Concept is briefly explained, and the flowdown from the Observatory Architecture and the Science Cases, with their corresponding Science Requirements, is presented. Interfaces with other equally important instruments are described, such as GMACS, a wide-field multi-object moderate-resolution optical spectrograph, and G-CLEF, a high-stability, high-resolution, echelle spectrograph operating in the visible range of the spectrum. Managerial aspects of the processes and documents involved are also explained, as well as the next steps for the incoming Conceptual Design phase.

Large astronomical instruments are often built by consortia of research institutes and universities. The different locations of the various teams, the common interests and shared responsibilities of the partner organizations, and the science driven approach of these projects bring unique challenges to conduct systems engineering efficiently. In this paper we report our positive experience within the METIS consortium that is building one of the three first-generation instruments for the ESO ELT. We developed a novel and fully collaborative systems engineering approach that decentralizes the responsibilities across discipline experts and subsystem providers using a webbased software tool to engineer requirements and interfaces. We discuss the problems that forced us to develop this new approach, describe the new processes and tools, and discuss the benefits, risks, and lessons learned.

A highly integrated Concurrent Engineering Team (CET) within a flight project evolves in its function and has the potential to provide many benefits through the project lifecycle. The benefits include superior systems-oriented design products, as well as overall improved project efficiency and higher-performing interpersonal relationships within the project. If physically integrated, this can manifest as a Concurrent Engineering Center (CEC) centrally located within a project’s physical office space. Here we discuss the process to establish and maintain a tightly integrated engineering and design team for providing highly streamlined service to the project, including a cost/benefits analysis discussion.

We present the development of the End-to-End simulator for the SOXS instrument at the ESO-NTT 3.5-m telescope. SOXS will be a spectroscopic facility, made by two arms high efficiency spectrographs, able to cover the spectral range 350-2000 nm with resolving power R≈4500. The E2E model allows to simulate the propagation of photons starting from the scientific target of interest up to the detectors. The outputs of the simulator are synthetic frames, which will be mainly exploited for optimizing the pipeline development and possibly assisting for proper alignment and integration phases in laboratory and at the telescope. In this paper, we will detail the architecture of the simulator and the computational model, which are strongly characterized by modularity and flexibility. Synthetic spectral formats, related to different seeing and observing conditions, and calibration frames to be ingested by the pipeline are also presented.

The new visual STELLA echelle spectrograph (SES-VIS) is a new instrument for the STELLA-II telescope at the Iza~na observatory on Tenerife. Together with the original SES spectrograph - which will still be used in the near IR - and a new H&K-optimized spectrograph, which is currently in the design phase, it will change the focus of the spectroscopic observations at STELLA towards the follow up of planetary candidates detected by upcoming surveys focusing on bright targets (TESS, PLATO2). It is optimized for precise radial velocity determination and long term stability. We have developed a ZEMAX based software package to create simulated spectra, which are then extracted using our new reduction package, which is based on the PEPSI software package. The focus has been put on calibration spectra, and the full range of available calibration sources (at field, Th-Ar, and Fabry-Perot), which can be compared to actual commissioning data once they are available. Furthermore we tested for the effect of changes of the environmental parameters to the wavelength calibration precision.

In the pursuit of directly imaging exoplanets, the high-contrast imaging community has developed a multitude of tools to simulate the performance of coronagraphs on segmented-aperture telescopes. As the scale of the telescope increases and science cases move toward shorter wavelengths, the required physical optics propagation to optimize high-contrast imaging instruments becomes computationally prohibitive. Gaussian Beamlet Decom- position (GBD) is an alternative method of physical optics propagation that decomposes an arbitrary wavefront into paraxial rays. These rays can be propagated expeditiously using ABCD matrices, and converted into their corresponding Gaussian beamlets to accurately model physical optics phenomena without the need of diffraction integrals. The GBD technique has seen recent development and implementation in commercial software (e.g. FRED, CODE V, ASAP)^1-3 but appears to lack an open-source platform. We present a new GBD tool developed in Python to model physical optics phenomena, with the goal of alleviating the computational burden for modeling complex apertures, many-element systems, and introducing the capacity to model misalignment errors. This study demonstrates the synergy of the geometrical and physical regimes of optics utilized by the GBD technique, and is motivated by the need for advancing open-source physical optics propagators for segmented- aperture telescope coronagraph design and analysis. This work illustrates GBD with Poisson's spot calculations and show significant runtime advantage of GBD over Fresnel propagators for many-element systems.

MAORY (Multi Conjugate Adaptive Optics RelaY) is an adaptive optics module able to compensate the wavefront disturbances affective the scientific observation. It is one of the four instruments approved for construction at the ELT and will be installed on the straight-through port of the telescope Nasmyth platform. Due to the size of the optical elements and the instruments itself, a careful evaluation of the optical effects related to the thermal inhomogeneity inside the instrument must be performed. The status of the analysis, the proposed validations, and the solutions proposed to mitigate these effects are presented in this work.

The European Southern Observatory (ESO) is managing the Extremely Large Telescope (ELT) system performance and budgets. The Telescope Main Structure, Hosted Optical Units and Scientific Instruments are designed and built outside ESO by contractors and consortia. Within this scope, system simulations are performed including the coupling between the Telescope Main Structure and its Hosted Units. Both dynamic couplings relevant for control-structure interaction, seismic loads, and micro-vibrations as well as quasi-static deflections are included in these simulations. This paper explains the modeling approach and the first simulation results.

Extremely Large Telescopes (ELTs) have precision requirements of a few tens of micro-arcsec for differential astrometry science cases. Each ELT project has its own astrometric error budget taking into consideration the specific design parameters of the observatory. A version of the Thirty Meter Telescope (TMT) astrometry error budget has previously been established and the details were presented at SPIE 2016.1 In this paper, we briefly revisit this error budget analysis. The main focus of this paper is a new python-based astrometry calculator which was developed for a more user-friendly application of the error budget. It facilitates direct evaluation of and comparison between different scenarios such as absolute vs differential astrometry; dense vs spare observation fields; science fields with and without reference objects, etc. The details of the astrometry calculator and its general functions are described. A few example science sensitivity studies are presented and the procedure of estimating astrometric errors for other observatories is outlined.

The Institute of Space and Astronautical Science (ISAS) began using Concept Maturity Levels (CMLs) in its space science program in 2017. The CMLs have been developed at the Jet Propulsion Laboratory (JPL) for measuring and communicating the maturity of space mission concepts. Using the JPL CML Matrix as reference, ISAS has been developing the ISAS version of CML matrix and checklist by considering difference in programmatics and systems engineering. The CML starts level 1 and we use up to level 5. The 150 checklist items are subdivided into 21 categories spanning from science objectives to cost estimation. We applied the ISAS CMLs to proposal templates for the last two AOs of the ISAS M-class missions and have been using the CML checklist to clarify the maturity level of existing missions up to the mission definition phase. In this paper, we present 1) what we needed to do in customizing the CML checklist for ISAS, 2) responses from the ISAS mission study teams, and 3) future plans for improvement.

The Sloan Digital Sky Survey V (SDSS-V) is an all-sky spectroscopic survey of < 6 million objects, designed to decode the history of the Milky Way, reveal the inner workings of stars, investigate the origin of solar systems, and track the growth of supermassive black holes across the Universe. Collaboratively, organizations across both academia and industry have partnered to overcome technical challenges and execute operational directives associated with commissioning the various mechanical, electrical, and software subsystems of SDSS-V. While this type of collaboration is not unique, the scale and complexity of next generation astronomical instruments is an emerging challenge that requires industrial systems and process engineering practices at a quasi-industrial scale. Driven by the success of multiplexed spectroscopic surveys, instrumentation is evolving to include systems with hundreds to thousands of components and sub-assemblies procured or produced from various sources. This trend requires the adoption of new and existing processes and best practices in the design, integration, and test of next generation astronomical instruments. The following discussion outlines those industrial systems and process engineering processes, methods, and practices, currently in the operational phase, for the design, integration, and test of the SDSS-V Focal Plane System (FPS). An emphasis is placed on processes, methods, and practices related to coordination of multiple contract manufacturing vendors and operational execution of small batch manufacturing.

Maunakea Spectroscopic Explorer (MSE) is an international project supported by a culturally and geographically diverse design team that is centrally managed by the Project Office. Given the finite PO resources, it is imperative to provide a comprehensive plan to set the design team’s performance standard. MSE has created an integrated plan with configuration management and review process over MSE’s development, from conceptual design to science operations. The plan is a document-based system driven by mandatory reviews through the MSE development phases. This paper defines the objectives and expected outcomes of each mandatory review, and lists the titles, contents, developmental maturity and Configuration Management (CM) status of every document in required review data package. This paper also describes the Change Control protocol, within the CM framework, managed by formal Change Control Boards using a collection of configurable documents provided by the design team and the PO.

Additive manufacturing (AM) offers many advantages, including material savings, lightening, design freedom, function integration, etc. In the case of cellular materials, regular structures (lattice and honeycomb) are particularly important due to their ability to reduce weight. However, the design process and FEM analysis of this type of structure is very high time-consuming. In order to mitigate this problem, we propose a modelling method, called "Equivalent Continuum Material", based on the treatment of a cellular material as a continuous mass. This document describes the method and presents examples of applications, to facilitate and understand its use.

HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from R (≡λ/Δλ) 3500 to 18000 and spatial sampling from 60 mas to 4 mas. Typically, optical performance of instruments can be analytically verified through commercially available software such as Zemax OpticStudio. Zemax offers – Application Programming Interface (ZOS-API) to either Python, MATLAB, or with plugins for C# and C++. This paper discusses the development of a procedure for implementing the ZOS-API for the E-ELT instrument - HARMONI. It demonstrates how these interfaces were developed to assess the performance of optical systems, by computing the differential wavefront error across the field. The paper then highlights the advantages of utilizing these interfaces as a tool for Systems Engineering. The benefits include optical budget management, customizable analysis, end to end modelling and requirements verification.

The METIS consortium in Portugal will build the support and access structure (WSS) for the mid-infrared, first generation ELT instrument - METIS. The specific characteristics of the METIS instrument and the ELT pose several challenges to building the WSS according to functional requirements. In addition, the assembly of the WSS and integrating the WSS with METIS poses its own particular challenges due to the singular loads and dimensions. Transversal to all phases of assembly and integration of the WSS and METIS is the concern for the safety of the instruments and personnel involved. We here present these requirements, challenges and mitigation measures in light of the assembly and integration of the WSS, and the WSS with METIS.

MAORY (Multi Conjugate Adaptive Optics RelaY) is one of the four instruments for the ELT (Extremely Large Telescope) approved for construction. It is an adaptive optics module able to compensate the wavefront disturbances affecting the scientific observations, achieving high strehl ratio and high sky coverage. MAORY will be installed on the straight-through port of the telescope Nasmyth platform and shall re-image the telescope focal plane to a wide field camera (MICADO) and in a future second instrument port. MAORY has completed the transition from developing requirements in Word and Excel, to CAMEO requirement management. A general overview of the requirement management system implemented in Cameo System Modeler is presented in this paper.

This paper proposes the usage of IBM Rational DOORS for the planning, controlling and supporting the verification of a system. This includes defining the verification methods & stages for technical requirements, defining the verification activities, establishing links between technical requirements and verification activities, defining the scope and success criteria of tests, monitoring the progress of the verification campaigns and finally the generation of the compliance matrix, all within a single tool. We illustrate the usage of this tool over the entire lifecycle of two recent projects (NAOMI, 4MOST) and give an outlook of its application to the verification of the Extremely Large Telescope (ELT).

The WEAVE instrument nearing completion for the William Herschel Telescope is a fiber-fed spectrograph operating in three different modes. Two comprise deployable fibers at the prime focus for point-like objects and small integral field units (IFU), the third is a large IFU placed at the center of the field. Three distinct fiber systems support these modes and route the photons to the spectrograph located on the Nasmyth platform 33m away: the first features 960+940 fibers and is duplicated to allow configuring the fibers on one plate while observation is carried out on the other, the second has 20 hexagonal IFUs featuring 37 fibers each, the third is a large array of 609 fibers with twice the former’s diameter. The large number of fibers and the diversity of their instantiation have made procurement of the parts and assembly of the custom cables a challenge. They involve project partners in France, the UK and the Netherlands and industrial partners in France, Canada, the USA and China to combine know-how and compress the schedule by parallelizing assembly of the cables. Besides the complex management that this induces, it has called for revising the fibers’ handling to relax tolerances and for a rigorous assessment of the conformity of the products. This paper tells the story of the making of the fiber links, presents the overall organization of the procurement and assembly chains together with the inspection and testing allowing for assessing the conformance of the hardware delivered.

In the framework of SKA1-Low design, a system modelling tool has been applied for drafting the whole Telescope. The model of the Telescope, and in particular that related to the Low Frequency Aperture array (LFAA), is detailed down to the level of the Firmware responsible for the signal processing The tool utilized for the design of the telescope model adopts the SysML graphics language. The presence of a unique Firmware’s model promoted the cooperation between the different groups around the world working of the Firmware and therefore it facilitates its development in a comprehensive and coherent way.

Systems Engineering requires the involvement of different engineering disciplines: Software, Electronics, Mechanics, Optics etc. Systems Engineering of Astronomical Instrumentation is no exception to this. A critical point is the handling of the different point of view of these disciplines often related to different tools and cultures. We developed an hybrid Model Based Systems Engineering (MBSE) approach to help the Sys. Eng. to keep control without imposing to the participants procedures and methods that may be seen as a bureaucratization. In the first phase, starting from the top-level requirements we deployed all the flow down to subsystem, including requirement generated by different use cases (calibration, AIV, …) and interfaces. This approach allowed us to have under control not only the requirement tracing, but also all the instrument operations “from cradle to grave”. In a next stage we will include also artifacts coming from the different engineering world (CAD, FEM, ...).

The 4-metre Multi-Object Spectroscopic Telescope (4MOST) is a new high-multiplex, wide-field spectroscopic survey facility under development for the Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.4 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R =6500), and 812 fibres transferring light to the high-resolution spectrograph (R ≈ 20000). For the end-to-end characterization of the 4MOST facility, we analyze the impact of the atmosphere at Paranal, VISTA telescope, wide field corrector, atmospheric dispersion compensator, tilting spine positioner, fibre system, spectrographs and detector systems. We present an exhaustive analysis of the most influential characteristics on the transmission efficiency for a 4MOST observation. Many environmental, telescope, and instrumental effects can be characterized in isolation, such as glass transmission. But there are also many effects that are caused by a combination of multiple components. For example, the residual atmospheric dispersion in combination with fibre positioning errors; or the fibre field position in combination with fibre tilt angle as well as the fibre focus position. To capture this complexity, we present a coherent quantitative assessment of each significant individual effect, as well as a relevant selection of effect combinations. To quantify the impact on the survey nature of the 4MOST instrument, we also introduce parts of the optical performance simulator TOAD, which was used to compute the impact each effect.

MSE is an upgrade of the existing 3.6-m Canada France Hawaii Telescope to an 11.25-m segmented primary mirror with a 1.5 square degrees field-of-view at the telescope’s prime focus. MSE will be massively multiplexed, observing 4,332 astronomical targets in every pointing. There are several subsystems needed to accomplish this. At MSE’s prime focus, a hexapod supports and positions several subsystems, including a wide field corrector barrel, a field derotator, guide and phasing cameras and a system of fiber optics with their individual piezo-actuated positioners. The fiber optics transmit light to two banks of low/moderate and high resolution spectrographs in optical to near-infrared wavelengths, several meters away. An array of primary mirror segments and several spectrographs are supported by the telescope structure as well. All of these subsystems are being designed and built by various partners and contributors around the world. Integration and compliance to requirements will require careful planning. To ensure this is successful, MSE has developed a plan for consistently flowing and tracking the many requirements from the Observatory Requirements into its subsystems. This involves reviewing subsystem design requirements that were developed in the conceptual design phase and updating them based on recent changes in the Observatory Requirements. Also, internal interfaces have been identified and will be closely controlled to ensure consistency throughout the project. This also involves consideration of several other topics related to requirements development and maintenance through the lifecycle of the project. We present an overview of the systems engineering management plans that will ensure consistency and traceability of requirements to science cases and stakeholder needs, as well as anticipating the verification process in the future work.

The Daniel K. Inouye Solar Telescope (DKIST) is a 4-meter solar observatory under construction at Haleakala, Hawaii. The Gregorian Optical System (GOS) is located at the secondary focus of the telescope and actuates different apertures and optics into the beam in order to facilitate configuration of the telescope optical beam for science and calibration activities. Due its location near Gregorian focus, the GOS design addresses several thermal challenges in order to maintain safe operating temperatures and prevent local seeing effects. In this paper we describe these thermal challenges and explain how we used modeling and simulation analyses to guide design choices. We will review results and limitations from the GOS lab acceptance testing process, look at lessons learned from integration at the summit, and share initial results from on sun testing. We conclude by comparing on sun test results with predictions from our design phase analyses.

The Square Kilometre Array (SKA) Observatory will construct two radio telescopes: SKA-Low in Australia and SKAMid in South Africa. When completed the SKA will be the largest radio telescope on earth, with unprecedented sensitivity and scientific capability. The first phase of SKA-Mid (called SKA1-Mid) includes an array of 197 dishantennas incorporating the recently completed MeerKAT antennas, to cover the frequency range of 350 MHz to 15.4 GHz. A Central Signal Processor, located close to the array, correlates and beamforms the 18Tb/s digitised data stream before it is transported to a dedicated super-computer in Cape Town for further processing. The combination of largescale deployment, significant real-time processing and geographic distribution poses significant architectural challenges. This paper presents the architectural highlights of the SKA1-Mid Telescope baseline design which has recently completed its Critical Design Review (CDR) on the path to starting construction in early 2021.

Systems engineering as a discipline is relatively new in the ground-based astronomy community and is becoming more common as projects become larger, more complex and more geographically diverse. Space and defense industry projects have been using systems engineering for much longer, however those projects don’t necessarily map well onto groundbased astronomy projects, for various reasons. Fortunately, many of the processes and tools have been documented by INCOSE, NASA, SEBoK and other organizations, however there can be incomplete or conflicting definitions within the process and implementation is not always clear. For ground-based systems engineers, adopting these existing processes can be confusing. One area of particular uncertainty involves how, when and where to document operations concepts in a way that captures astronomers’ needs, translates them into concise and complete requirements without over-constraining the design teams or over-burdening the project with complex requirements and document management procedures. We present the criteria and outcome of the solution(s) chosen from the perspective of two different projects: a new observatory that is planning its operations (Maunakea Spectrocopic Explorer, MSE) and a new instrument at a longestablished observatory (Gemini - GIRMOS). Quite possibly, this will not answer the question in the title and may raise more questions. We welcome that discussion.

Wide-Field Adaptive Optics systems will be a key component of the future generation of Extremely Large Telescopes. All the components of such Adaptive Optics systems have to be precisely specified using the atmospheric turbulence parameters of the site, particularly the profile of the refractive index structure constant C²_n (h). The monitor PML (Profiler of Moon Limb), for the extraction of the C²_n (h) profile with high vertical resolution for nighttime and daytime conditions, has been developed and is now routinely exploited at the Calern Observatory (French Riviera). The PML instrument uses a differential method with two small subapertures mask through which the Moon limb or Sun edge are observed leading to a continuum of double stars allowing a scan of the whole atmosphere with high resolution in altitude. In addition, PML provides, in real time, a complete characterization of the atmospheric turbulence since it is able to measure the other turbulence parameters like the total seeing and the isoplanatic angle.

The Thirty Meter Telescope (TMT) has three instruments in development for first light, and another 6 notional instruments planned for implementation over the first decade of operations. All of these instruments require cryogenic cooling of detectors, as well as optics in most cases. This paper describes the instrument cooling capacity requirements, the trade study that led to the design solution, and the overall layout of the conceptual design. TMT has chosen to build an on-site liquid nitrogen generation plant, and supply liquid nitrogen to the instruments using an autofill system. TMT also supplies compressed helium to instruments with cryocoolers for optics and detectors that require cooling below the boiling point of liquid nitrogen.

Missions to directly detect exoplanets with a coronagraph, such as the potential Habitable Exoplanet (HabEx) mission, require an optical telescope with extreme wavefront stability. The key systems engineering question is: ‘How stable?’ The poetic answer is 10 picometers per 10 minutes. But, what is the actual spatial distribution of this error allocation? This paper defines a science-driven systems-engineering process to derive the telescope’s wavefront stability error budget specification from the coronagraph’s performance; reviews previous studies into coronagraph sensitivity to wavefront error instability; and demonstrates the method by comparing the performance of coronagraph telescope combinations.

Publishers Note: This paper, and video were originally published on 14 December 2020, both were replaced with a corrected/revised version on 9 April 2020. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.