Paul Jeffers

The Visible and Infrared Survey Telescope for Astronomy (VISTA): Design, technical overview, and performance

The VISTA project was made possible by funding from the UK Joint Infrastructure Fund (JIF) and PPARC (later STFC).

VISTA: project status

VISTA is a 4-m wide field survey telescope with a near infra-red camera and a demanding f/1 primary design now well into its manufacturing phase. We contracted out major items, and generated a coordinated approach to the management of engineering budgets through systems engineering, risks through risk management, and safety through the generation of safety cases. Control of the interfaces and science requirements has been maintained and developed through the current phase. The project is developing the commissioning plan to deliver an effective and safe facility. The current status of VISTA is presented as we move towards the on site integration phase.

Construction status of the Daniel K. Inouye Solar Telescope

We provide an update on the construction status of the Daniel K. Inouye Solar Telescope. This 4-m diameter facility is designed to enable detection and spatial/temporal resolution of the predicted, fundamental astrophysical processes driving solar magnetism at their intrinsic scales throughout the solar atmosphere. These data will drive key research on solar magnetism and its influence on solar winds, flares, coronal mass ejections and solar irradiance variability. The facility is developed to support a broad wavelength range (0.35 to 28 microns) and will employ state-of-the-art adaptive optics systems to provide diffraction limited imaging, resolving features approximately 20 km on the Sun. At the start of operations, there will be five instruments initially deployed: Visible Broadband Imager (VBI; National Solar Observatory), Visible SpectroPolarimeter (ViSP; NCAR High Altitude Observatory), Visible Tunable Filter (VTF (a Fabry-Perot tunable spectropolarimeter); Kiepenheuer Institute for Solarphysics), Diffraction Limited NIR Spectropolarimeter (DL-NIRSP; University of Hawaii, Institute for Astronomy) and the Cryogenic NIR Spectropolarimeter (Cryo-NIRSP; University of Hawaii, Institute for Astronomy). As of mid-2016, the project construction is in its 4th year of site construction and 7th year overall. Major milestones in the off-site development include the conclusion of the polishing of the M1 mirror by University of Arizona, College of Optical Sciences, the delivery of the Top End Optical Assembly (L3), the acceptance of the Deformable Mirror System (Xinetics); all optical systems have been contracted and are either accepted or in fabrication. The Enclosure and Telescope Mount Assembly passed through their factory acceptance in 2014 and 2015, respectively. The enclosure site construction is currently concluding while the Telescope Mount Assembly site erection is underway. The facility buildings (Utility and Support and Operations) have been completed with ongoing work on the thermal systems to support the challenging imaging requirements needed for the solar research. Finally, we present the construction phase performance (schedule, budget) with projections for the start of early operations.

VISTA secondary mirror drive performance and test results

This paper summarizes the main aspects of the design and qualification test results of the secondary mirror mechanism for the VISTA Telescope. A design overview is presented, with detailed description of the main aspects of the system including the electromechanical part and the control system. Also a description of the test facilities and test methodologies is provided prior to the presentation and discussion of the performance test results.

VISTA M1 support system

The VISTA Telescope1 is obtaining superb survey images. The M1 support system is essential to image quality and uses astatic pneumatic supports to balance the M1 against the varying effects of gravity and wind, with four axes being actively controlled via software and CANbus. The system also applies externally determined active optics force patterns. The mechanical, electronic, software and control design and as-built operation of the system are described, with the practical design points discussed.

VISTA Telescope Mount - Factory testing prior to optics integration

VISTA is a survey telescope which will deliver 0.5 arc second images over a 2 degree diameter unvignetted field of view. The Telescope Work Package which includes both the Mount and M1 support system is being designed and built by VertexRSI. The Contract includes an extensive factory test programme after full assembly of the telescope systems. The main optical elements in projects this size are ordered early so that they are ready for integration with the telescope on site. This means that testing of the telescope with its optics in the factory environment is rarely possible. So to try and avoid problems during site integration, the scope and extent of hardware and control system factory testing is significant and should be suitably in-depth. This paper describes the metrology and testing carried out to date in the factory environment. In addition the axis control system was simulated using Matlab-Simulink models. The models were also used as the basis of software verification using hardware-in-the-loop tests in a model-based development process. This development process and subsequent factory testing is described in some detail, and covers the mount axes and the M1 support system. In conclusion this paper discusses the perceived usefulness of the extent of the factory testing employed and how this is expected to mesh with the process of telescope and optics integration on site.

Construction update of the Daniel K. Inouye Solar Telescope project

Construction of the Daniel K. Inouye Solar Telescope (DKIST) is well underway on the Haleakalā summit on the Hawaiian island of Maui. Featuring a 4-m aperture and an off-axis Gregorian configuration, the DKIST will be the world’s largest solar telescope. It is designed to make high-precision measurements of fundamental astrophysical processes and produce large amounts of spectropolarimetric and imaging data. These data will support research on solar magnetism and its influence on solar wind, flares, coronal mass ejections, and solar irradiance variability. Because of its large aperture, the DKIST will be able to sense the corona’s magnetic field—a goal that has previously eluded scientists—enabling observations that will provide answers about the heating of stellar coronae and the origins of space weather and exo-weather. The telescope will cover a broad wavelength range (0.35 to 28 microns) and operate as a coronagraph at infrared (IR) wavelengths. Achieving the diffraction limit of the 4-m aperture, even at visible wavelengths, is paramount to these science goals. The DKIST’s state-of-the-art adaptive optics systems will provide diffraction-limited imaging, resolving features that are approximately 20 km in size on the Sun. At the start of operations, five instruments will be deployed: a visible broadband imager (VTF), a visible spectropolarimeter (ViSP), a visible tunable filter (VTF), a diffraction-limited near-IR spectropolarimeter (DLNIRSP), and a cryogenic near-IR spectropolarimeter (cryo-NIRSP). At the end of 2017, the project finished its fifth year of construction and eighth year overall. Major milestones included delivery of the commissioning blank, the completed primary mirror (M1), and its cell. Commissioning and testing of the coudé rotator is complete and the installation of the coudé cleanroom is underway; likewise, commissioning of the telescope mount assembly (TMA) has also begun. Various other systems and equipment are also being installed and tested. Finally, the observatory integration, testing, and commissioning (IT&C) activities have begun, including the first coating of the M1 commissioning blank and its integration within its cell assembly. Science mirror coating and initial on-sky activities are both anticipated in 2018.

DKIST telescope mount factory testing overview and lessons learned

The Daniel K Inouye Solar Telescope (DKIST) will be the largest solar telescope in the world, and will be able to provide the sharpest views ever taken of the solar surface. The telescope has a 4m aperture primary mirror, however due to the off axis nature of the optical layout, the telescope Mount has proportions similar to an 8 metre class telescope. The Telescope Mount Assembly (TMA) includes both the telescope Mount and the 16m diameter laboratory table or Coudé Rotator. The Coudé Rotator supports the full instrument suite of up to 40 tonnes and has full rotation capabilities similar to the Mount azimuth axis. The TMA has been going through the design, fabrication and assembly process since 2009 with Ingersoll Machine Tool’s and this culminated with the Factory Acceptance Testing (FAT). The preparation for the FAT started not long after the Final Design Review was complete and planning continued through the assembly stages. The official Factory Acceptance testing of the Coudé Rotator was conducted during May/Jun 2014 and the Mount in Feb through Apr 2015. This paper provides an overview and discussion of the testing that was carried out. The depth and extent of testing will be described with discussion on what we would do differently next time. Also details of the preparation / process that lead into the testing will be presented. Most importantly the results will be summarized and lessons learned during the testing provided as well as discussion on how this influences the planned site assembly and extent of re-test post assembly.

Performance verification of the DKIST Mount and Coudé Laboratory

The former Advanced Technology Solar Telescope (ATST), now renamed to Daniel K. Inouye Solar Telescope (DKIST) will be the largest solar telescope in the world – with a 4m aperture primary mirror and a 16m diameter co-rotating “Coudé” laboratory located within the telescope pier. Both, the telescope mount and the Coudé laboratory use for their azimuth axis a new kind of bearing technology, so called R-guides, which minimize later maintenance efforts, avoid energy consumption and the risk of oil spill of conventional hydrostatic bearings. The paper describes the integrated modeling approach for the verification of the challenging DKIST jitter requirement of 0.075 arcsec rms with the new bearing system, including initial system engineering guidelines, finite element evaluations, system dynamics and end-to-end jitter simulations, factory tests of subsystems and components, and the commissioning of the trial assembled Coudé table and later the telescope mount.

ATST telescope mount: telescope of machine tool

The Advanced Technology Solar Telescope (ATST) will be the largest solar telescope in the world, and will be able to provide the sharpest views ever taken of the solar surface. The telescope has a 4m aperture primary mirror, however due to the off axis nature of the optical layout, the telescope mount has proportions similar to an 8 meter class telescope. The technology normally used in this class of telescope is well understood in the telescope community and has been successfully implemented in numerous projects. The world of large machine tools has developed in a separate realm with similar levels of performance requirement but different boundary conditions. In addition the competitive nature of private industry has encouraged development and usage of more cost effective solutions both in initial capital cost and thru-life operating cost. Telescope mounts move relatively slowly with requirements for high stability under external environmental influences such as wind buffeting. Large machine tools operate under high speed requirements coupled with high application of force through the machine but with little or no external environmental influences. The benefits of these parallel development paths and the ATST system requirements are being combined in the ATST Telescope Mount Assembly (TMA). The process of balancing the system requirements with new technologies is based on the experience of the ATST project team, Ingersoll Machine Tools who are the main contractor for the TMA and MT Mechatronics who are their design subcontractors. This paper highlights a number of these proven technologies from the commercially driven machine tool world that are being introduced to the TMA design. Also the challenges of integrating and ensuring that the differences in application requirements are accounted for in the design are discussed.