The Giant Magellan Telescope (GMT) is one of three planned ground-based optical/IR Extremely Large Telescopes (ELTs) that will provide a generational leap in ground-based Optical/IR capability. The GMT Mount is the structural, mechanical, hydraulic, and electronic system that provides the overall framework for mounting and alignment of optics and science instruments, supports payloads and utilities, and provides the three main axes of motion consisting of azimuth, elevation, and Gregorian Instrument Rotator (GIR) rotations. The GMTO Corp. completed in 2019 a multi-stage acquisition process that led to the selection of OHB Digital Connect (ODC, formerly MT-Mechatronics or MTM) and Ingersoll Machine Tools (IMT) to supply the final design, fabrication, and installation of the GMT Mount. The Final Design Review of the Mount subsystem was successfully passed in June 2023. The fabrication of the Mount is split into two phases comprising first the rotating azimuth base structure and secondly the elevation and optical support moving structures. The Mount will be assembled and tested at the IMT factory to the largest feasible assembly state where all three motion axes and critical systems will be functionally tested. The Mount will then be disassembled, shipped, and reassembled and tested at the GMT's Las Campanas site in Chile. The first phase of fabrication has begun starting with the Azimuth Track Segments. Full factory functional testing of the Hydrostatic Bearing System (HBS), the electric Direct-Drive System, the Earthquake Damping System (EDS), and the Azimuth cable wrap will be completed during the first phase of fabrication. This paper will describe the final design configuration of the Mount, major subassemblies, fabrication and test phasing, fabrication highlights to-date, and an overview of the prototype testing that validated the final design parameters.

The Giant Magellan Telescope (GMT) is one of three planned ground-based optical/IR Extremely Large Telescopes (ELTs) that will provide a generational leap in ground-based Optical/IR capability. The GMTO Corp. completed in 2019 a multi-stage acquisition process that led to the selection of OHB Digital Connect (formerly MT-Mechatronics or MTM) and Ingersoll Machine Tools (IMT) to supply the final design, fabrication, and installation of the GMT Mount. The ~2000 metric ton GMT Mount comprises the telescope structures, mechanisms, and utilities but does not include the optics and science instruments. This paper provides a general overview of the technical scope of the GMT Mount including the key and driving requirements, systems engineering framework, and planned design development. Due to the GMT site location in Chile, the Mount design must accommodate a challenging seismic environment. Major Mount subsystems are also described including the Hydrostatic Bearing System (HBS), Gregorian Instrument Rotator (GIR), and the Azimuth Track and its interface to the telescope Pier. In addition, a summary is presented of the design path forward to the Final Design Review (FDR) from the point of completing the Preliminary Design Review (PDR) in early 2021, including the current status of critical prototyping efforts. Finally, management processes are outlined that are necessary to execute the Mount design-build contract spanning the next 8-9 years.

The Next Generation Very Large Array (ngVLA) project to replace the VLA telescope in New Mexico continues to move forward. Concept designs for 15m, 18m, and 6m offset Gregorian antennas based on the Single-piece Rim-supported Composite (SRC) reflector concept have been developed at NRC, the 18m and 6m designs became part of the ngVLA System Reference Design (SRD). The Reference Design array is composed of a main array of 244 x 18m antennas and a short baseline array of 19 x 6m antennas. In the initial design iteration of the 6m antenna, as used in the SRD, was essentially a scaled down version 18m. This design exercise provided a costed concept appropriate for the SRD but did not meet one critical requirement; the ability to close pack the antennas. Following the release of the SRD the team at NRC took a clean piece of paper approach to the 6m antenna design driven by the close packing requirement. This paper will presents the design path from the ngVLA SRD to the latest design.

The Canada France Hawaii Telescope Corporation (CFHT) plans to repurpose its observatory on the summit of Maunakea and operate a new wide field spectroscopic survey telescope, the Maunakea Spectroscopic Explorer (MSE). MSE will upgrade the observatory with a larger 11.25m aperture telescope and equip it with dedicated instrumentation to capitalize on the site, which has some of the best seeing in the northern hemisphere, and offer its user's community the ability to do transformative science. The knowledge and experience of the current CFHT staff will contribute greatly to the engineering of this new facility. MSE will reuse the same building and telescope pier as CFHT. However, it will be necessary to upgrade the support pier to accommodate a bigger telescope and replace the current dome since a wider slit opening of 12.5 meters in diameter is needed. Once the project is completed the new facility will be almost indistinguishable on the outside from the current CFHT observatory. MSE will build upon CFHT's pioneering work in remote operations, with no staff at the observatory during the night, and use modern technologies to reduce daytime maintenance work. This paper describes the design approach for redeveloping the CFHT facility for MSE including the infrastructure and equipment considerations required to support and facilitate nighttime observations. The building will be designed so existing equipment and infrastructure can be reused wherever possible while meeting new requirement demands. Past experience and lessons learned will be used to create a modern, optimized, and logical layout of the facility. The purpose of this paper is to provide information to readers involved in the MSE project or organizations involved with the redevelopment of an existing observatory facility for a new mission.

(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is intended as a concise reference guide to all aspects of the scientific and technical design of MSE, for the international astronomy and engineering communities, and related agencies. The current version is a status report of MSE's science goals and their practical implementation, following the System Conceptual Design Review, held in January 2018. MSE is a planned 10-m class, wide-field, optical and near-infrared facility, designed to enable transformative science, while filling a critical missing gap in the emerging international network of large-scale astronomical facilities. MSE is completely dedicated to multi-object spectroscopy of samples of between thousands and millions of astrophysical objects. It will lead the world in this arena, due to its unique design capabilities: it will boast a large (11.25 m) aperture and wide (1.52 sq. degree) field of view; it will have the capabilities to observe at a wide range of spectral resolutions, from R2500 to R40,000, with massive multiplexing (4332 spectra per exposure, with all spectral resolutions available at all times), and an on-target observing efficiency of more than 80 designed to excel at precision studies of faint astrophysical phenomena. It will also provide critical follow-up for multi-wavelength imaging surveys, such as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation Very Large Array.

The suspension and rotation systems (typically called bogies) for Extremely Large Telescope (ELT) enclosures will carry structures that are 2-3 times greater in diameter and much heavier than enclosures for the previous generation of 6-10m telescopes. Via on-site visits and/or engineering documentation, we have surveyed eleven optical, infrared, and submillimeter 3-15m telescope enclosures, and report on key design features of the suspension and rotation systems, including wheel and track geometry, the wheel/track interface, average load per wheel, rotation drive method, etc. We discuss key considerations for the development of future suspension and rotation systems for ELT enclosures.

The Maunakea Spectroscopic Explorer is designed to be the largest non-ELT optical/NIR astronomical telescope, and will be a fully dedicated facility for multi-object spectroscopy over a broad range of spectral resolutions. The MSE design has progressed from feasibility concept into its current baseline design where the system configuration of main systems such as telescope, enclosure, summit facilities and instrument are fully defined. This paper will describe the engineering development of the main systems, and discuss the trade studies to determine the optimal telescope and multiplexing designs and how their findings are incorporated in the current baseline design.

The Canada-France-Hawaii-Telescope Corporation (CFHT) plans to repurpose its observatory on the summit of Maunakea and operate a (60 segment) 11.25m aperture wide field spectroscopic survey telescope, the Maunakea Spectroscopic Explorer (MSE). The prime focus telescope will be equipped with dedicated instrumentation to take advantage of one of the best sites in the northern hemisphere and offer its users the ability to perform large surveys. Central themes of the development plan are reusing and upgrading wherever possible. MSE will reuse the CFHT site and build upon the existing observatory infrastructure, using the same building and telescope pier as CFHT, while minimizing environmental impact on the summit. MSE will require structural support upgrades to the building to meet the latest building seismic code requirements and accommodate a new larger telescope and upgraded enclosure. It will be necessary to replace the current dome since a larger slit opening is needed for a larger telescope. MSE will use a thermal management system to remove heat generated by loads from the building, flush excess heat from lower levels, and maintain the observing environment temperature. This paper describes the design approach for redeveloping the CFHT facility for MSE. Once the project is completed the new facility will be almost indistinguishable on the outside from the current CFHT observatory. Past experience and lessons learned from CFHT staff and the astronomical community will be used to create a modern, optimized, and transformative scientific data collecting machine.

The Maunakea Spectroscopic Explorer (MSE; formerly Next Generation Canada-France-Hawaii Telescope) is a dedicated, 10m aperture, wide-field, fiber-fed multi-object spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The enclosure vent configuration design study is the last of three studies to examine the technical feasibility of the proposed MSE baseline concept. The enclosure vent configuration study compares the aero-thermal performance of three enclosure ventilation configurations based on the predicted dome thermal seeing and air flow attenuation over the enclosure aperture opening of a Calotte design derived from computational fluid dynamics simulations. In addition, functional and operation considerations such as access and servicing of the three ventilation configurations is discussed.

As steel structures become larger, taller, and longer, the demand for high-strength steel increases. High-strength steels exhibit different mechanical characteristics and hysteretic behavior for dynamic deformation than for quasi-static deformation. This is attributable to the strain rate and temperature dependence of steel materials when nonuniformly deformed in the plastic region. Therefore, to analyze and design structures using high-strength steels under dynamic cyclic loading, such as earthquake loading, it is necessary to consider the special dynamic hysteresis model of high-strength steels. In particular, when using finite-element (FE) analysis programs one should use the proper material characteristics for those steels. In this paper, dynamic hysteresis models for standard high-strength steels, with tensile strengths of 600 and 800 MPa, are formulated based on results of tensile tests and low-cycle fatigue tests over a range of strain rates from 10-4-10 s-1. A three-dimensional elastic-plastic finite-element analysis program using a newly formulated dynamic hysteresis model is developed by the writers. Accuracy and validity of the developed finite-element analysis program is verified by correlation of the analytical and experimental results.

The Next Generation Canada-France-Hawaii Telescope is a dedicated, 10m aperture, wide-field, fiber-fed multiobject spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The Next Generation Canada-France-Hawaii Telescope baseline concept assumes the new facility is built on the existing Canada-France-Hawaii Telescope telescope pier and enclosure pier and occupies the same three dimensional exterior “footprint”. Three technical studies have been planned to examine the validity of these assumptions. The technical studies are executed in series as they represent technical decision points in a logical sequence. The three technical studies in succession are: 1. Telescope Pier Study – Load Capacity and Structural Interface, 2. Enclosure Fixed Base Study – Telescope and Enclosure Configuration and Load Capacity and 3. Aero- Thermal Study – Dome Thermal Seeing and Air Flow Attenuation over the Enclosure Aperture Opening. The paper outlines the baseline facility (telescope, spectrograph and enclosure) concept and the status of these studies, and discusses the proposed telescope and enclosure configuration in terms of the redevelopment assumptions. A consolidated feasibility study report will be submitted to the CFHT Board and Science Advisory Committee in the Fall of 2012, with first light for the facility aiming to be in the early 2020s.

The Thirty Meter Telescope (TMT) project has chosen a reference configuration with the telescope elevation axis above the primary mirror. The TMT telescope design has a segmented primary mirror, with 738 segments, nominally 1.2 m across corners, and it uses an articulated tertiary mirror to feed science light to predefined instrument positions on two large Nasmyth platforms. This paper outlines the development of the telescope structural design to meet the motion requirements related to the image quality error budget. The usage of opto-structural performance evaluation tools such as Merit Function Routine are described in addition with the optimization techniques used during the telescope structure design development.