The PFS (Prime Focus Spectrograph) instrumentation is nearly complete finally. The only missing hardware is the last two spectrograph modules, but the installations are ongoing well as of this abstract being written and are expected to complete very soon. On-sky engineering tests and observations have been carried out continually since September 2021 and, after the resolutions of some major issues on hardware and software, the team successfully observed many targeted stars over the entire field of view (Engineering First Light) in September 2022. The performances and operation of the instrument are being optimized e.g. in the accuracy and speed of fiber positioning process. Long integrations of relatively faint objects are being taken to validate expected increase of signal-to-noise ratio. Given the science operation will start soon after the commissioning process is complete, various procedures of proposing, planning, & executing observations, processing data & assessing their qualities, and delivering data to observers are being developed and tested. In this contribution, a top-level summary of these achievements and ongoing progresses and future perspectives will be provided.
The Spectrograph System (SpS) of Subaru Prime Focus Spectrograph is fed by 2400 fibers and consists of four identical spectrograph modules with 4 arms and 600 fibers each. This paper outlines the overall integration process for the spectrograph module series as completed at the Subaru Telescope. Many partners from the Subaru PFS Collaboration and industry contributed to this large multi-object spectrograph system. The initial integration of the so-called "one-channel prototype" began in 2015. The first spectrograph module was delivered to Subaru in 2019, and the fourth module was delivered in late 2023, with delays due to both technical difficulties and scheduling challenges, including the impact of COVID-19 on the large PFS spectrograph system collaboration. The integration and validation of each spectrograph module were performed at the Laboratoire d’Astrophysique de Marseille (LAM) prior to delivery and full integration at the Subaru Telescope. First, we briefly review the opto-mechanical design and development strategy for the SpS. We present the integration and testing procedures developed for this mini-series of four spectrograph modules. Several specific AIT tools were innovative and key to the process, and are worth reporting, including the software tools required for functional tests, housekeeping, and environment monitoring during integration, analysis of dimensional metrology, test and verification of optical alignment, and overall performance assessment. Specific processes were also developed for analyzing and resolving anomalies and issues encountered. We detail the strategies developed to resolve technical issues: thermal and vacuum performance; dimensional and optical metrology processes to correct for focus/tilt anomalies observed at the focal plane; handling, alignment, and optical testing of large optics such as the 340x340x20mm Volume Phase Holographic Grating (VPHG). We briefly report on a grating orientation issue discovered before the delivery of the last module, which is reported elsewhere. We quickly report the integration logistics: managing the shipping process, custom, and deliveries of many parts and modules among partners since 2014, and the final delivery and installation at the Subaru Telescope at the summit of Mauna Kea in Hawai`i in 2019, 2022, and 2023. We then dedicate a full section to the optical and thermal performance for the largest 8m-class multi-object spectrograph: the spectral channels and camera alignment performance results and the detailed optical performance of the four spectrograph modules (extracted from internal extended performance reports).
PFS (Prime Focus Spectrograph) is an ultra-wide-field, multi-object spectrograph currently being commissioned at Subaru telescope. The focal plane is made of ∼2400 science fibers and fiber positioners at the telescope prime focus, covering a field of view of 1.3 deg in diameter. The science fibers will be connected to 4 identical spectrograph modules, each receiving ∼600 fibers. Every spectrograph module will host 3 cameras, covering the blue (380–650 nm), red (630–970 nm) and near-infrared (940–1260 nm) wavelengths. This presentation will focus on the completion of the PFS spectrograph modules at the Subaru telescope. We will present their integration and test processes and measured performance, as well as the technical challenges encountered along the way, and the solutions used to correct them.
Publisher's Note: This paper, originally published on 29 August 2022, was replaced with a corrected/revised version on 15 September 2023. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews.
The SCAO Sensors subsystem (SCAOS) is located within the Natural Guide Star Sensors (NGSS) system which includes several wavefront sensors (WFS) to cover the needs of the different HARMONI observing modes and operates in a cold, thermally stabilized (+2°C) and dry gas environment for thermal background limitation. To reach the required performance, the SCAOS will use different modules and mechanisms among which, two particularly critical devices have been prototyped and are tested: The SCAOS Pyramid Modulator Unit (SPMU) and the SCAOS Object Selection Mechanism (SOSM). Both devices are tip-tilt mirrors but have very different specifications (amplitude and speed). In this work, we will present and discuss the design, the assembly and the full test (performance, control) of the two systems, in both ambient and cold environments.
PFS (Prime Focus Spectrograph), a next generation facility instrument on the Subaru telescope, is now being tested on the telescope. The instrument is equipped with very wide (1.3 degrees in diameter) field of view on the Subaru’s prime focus, high multiplexity by 2394 reconfigurable fibers, and wide waveband spectrograph that covers from 380nm to 1260nm simultaneously in one exposure. Currently engineering observations are ongoing with Prime Focus Instrument (PFI), Metrology Camera System (MCS), the first spectrpgraph module (SM1) with visible cameras and the first fiber cable providing optical link between PFI and SM1. Among the rest of the hardware, the second fiber cable has been already installed on the telescope and in the dome building since April 2022, and the two others were also delivered in June 2022. The integration and test of next SMs including near-infrared cameras are ongoing for timely deliveries. The progress in the software development is also worth noting. The instrument control software delivered with the subsystems is being well integrated with its system-level layer, the telescope system, observation planning software and associated databases. The data reduction pipelines are also rapidly progressing especially since sky spectra started being taken in early 2021 using Subaru Nigh Sky Spectrograph (SuNSS), and more recently using PFI during the engineering observations. In parallel to these instrumentation activities, the PFS science team in the collaboration is timely formulating a plan of large-sky survey observation to be proposed and conducted as a Subaru Strategic Program (SSP) from 2024. In this article, we report these recent progresses, ongoing developments and future perspectives of the PFS instrumentation.
PFS (Prime Focus Spectrograph), a next generation facility instrument on the Subaru telescope, is a very wide- field, massively multiplexed, and optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed in the 1.3 degree-diameter field of view. The spectrograph system has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously deliver spectra from 380nm to 1260nm in one exposure. The instrumentation has been conducted by the international collaboration managed by the project office hosted by Kavli IPMU. The team is actively integrating and testing the hardware and software of the subsystems some of which such as Metrology Camera System, the first Spectrograph Module, and the first on-telescope fiber cable have been delivered to the Subaru telescope observatory at the summit of Maunakea since 2018. The development is progressing in order to start on-sky engineering observation in 2021, and science operation in 2023. In parallel, the collaboration is trying to timely develop a plan of large-sky survey observation to be proposed and conducted in the framework of Subaru Strategic Program (SSP). This article gives an overview of the recent progress, current status and future perspectives of the instrumentation and scientific operation.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.