The instrumentation of the Prime Focus Spectrograph (PFS), a next generation facility instrument on the Subaru telescope, is now in the final phase of its commissioning process and its general, open-use operations for sciences will provisionally start in 2025. The instrument enables simultaneous spectroscopy with 2386 individual fibers distributed over a very wide (∼1.3 degrees in diameter) field of view on the Subaru’s prime focus. The spectra cover a wide range of wavelengths from 380nm to 1260nm in one exposure in the Low-Resolution (LR) mode (while the visible red channel has the Medium-Resolution (MR) mode as well that covers 710−885nm). The system integration activities at the observatory on Maunakea in Hawaii have been continuing since the arrival of the Metrology Camera System in 2018. On-sky engineering tests and observations have also been carried out continually since September 2021 and, despite various difficulties in interlacing commissioning processes with development activities on the schedule and addressing some major issues on hardware and software, the team successfully observed many targeted stars as intended over the entire field of view (Engineering First Light) in September 2022. Then in parallel to the arrival, integration and commissioning of more hardware components, validations and optimizations of the performance and operation of the instrument are ongoing. The accuracy of the fiber positioning process and the speed of the fiber reconfiguration process have been recently confirmed to be ∼ 20−30μm for 95% of allocated fibers, and ∼130 seconds, respectively. While precise quantitative analyses are still in progress, the measured throughput has been confirmed to be consistent with the model where the information from various sub-components and sub-assemblies is integrated. Long integration of relatively faint objects are being taken to validate an expected increase of signal-to-noise ratio as more exposures are taken and co-added without any serious systematic errors from, e.g., sky subtraction process. The PFS science operation will be carried out in a queue mode by default and various developments, implementations and validations have been underway accordingly in parallel to the instrument commissioning activities. Meetings and sessions are arranged continually with the communities of potential PFS users on multiple scales, and discussions are iterated for mutual understanding and possible optimization of the rules and procedures over a wide range of processes such as proposal submission, observation planning, data acquisition and data delivery. The end-to-end processes of queue observations including successive exposures with updated plans based on assessed qualities of the data from past observations are being tested during engineering observations, and further optimizations are being undertaken. In this contribution, a top-level summary of these achievements and ongoing progresses and future perspectives will be provided.
Prime Focus Spectrograph (PFS) is a next generation instrument mounted on the Subaru telescope. It is a fiber-fed multiplex system covering a wide field of view (1.3 degree in diameter), which enables to acquire approximately 2400 spectra of science objects simultaneously. In order to efficiently use fibers, open-use programs will share fibers with each other (the fiber-sharing mode). Here, we introduce the PFS Pointing Planner (PPP), the tool to optimize the pointing centers. Its goal is to efficiently observe all allocated time of science programs while assigning as many fibers as possible to science targets on each pointing. The tool incorporates a flexible weight scheme which considers factors such as the science priority, surface density and exposure time. We present the simulation results of PPP with mock science programs, and discuss its performance in diverse science cases.
In this paper, we present our approach regarding the compensation of defective pixels in the infrared array detector used in the NINJA spectrograph for the Subaru Telescope. While it is typical to use a detector with minimal defective pixels for infrared spectrographs, our HAWAII-2RG detector has a central area with a defective pixel rate of 10%. Therefore, we compensate for defective pixels by mechanically shifting the detector along the focal plane in the direction of dispersion. This approach applies the concept of dithering in imaging observation to a spectrograph, and the shifting mechanism is designed to have a maximum movement distance of 8 mm. We present the expected performance of the compensation and the actual mechanical structure fabricated.
Near-INfrared and optical Joint spectrograph with Adaptive optics (NINJA) is an optical to near-infrared (NIR) spectrograph optimized for the laser tomography adaptive optics (LTAO) system at the Subaru telescope, realized by the adaptive secondary mirror and four-laser guide star (LGS) system now under development. One of the primary science objectives of this spectrograph is wide-band spectroscopic follow-up of transient sources like GRB, supernovae, or gravitational wave sources down to 22 mag in the J -band. NINJA consists of two spectrograph units, one is in the optical (0.35-0.85 µm) and the other in the NIR (0.85-2.5 µm), and a fore-optics which splits the light from the telescope to the spectrographs and wavefront sensors (WFSs) of LTAO. Each spectrograph has a slit with 0.35′′ wide and 5′′ long, and a spectral resolution of R=3000-4000 utilizing a grating. The four LGSs are planned to be arranged on a circle around the slit with a radius of about 8′′, and a patrol field of view (FoV) of a tip-tilt guide star is about 2′ diameter. With two dichroic mirrors, the fore-optics splits the light of the FoV into three wavelength ranges of 0.35-0.85 µm, 0.85-2.5 µm, and 0.589 µm for LGS. In this paper, we report the overall system of NINJA and a conceptual design of the optics.
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.
PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1.3 deg field of view. The spectrograph has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure at a resolution of ~ 1.6-2.7Å. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project recently started undertaking the commissioning process of a subsystem at the Subaru Telescope side, with the integration and test processes of the other subsystems ongoing in parallel. We are aiming to start engineering night-sky operations in 2019, and observations for scientific use in 2021. This article gives an overview of the instrument, current project status and future paths forward.
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