The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber spectrograph designed for the prime focus of the 8.2m Subaru telescope. PFS will cover 1.3 degrees diameter field with 2394 fibers to complement the imaging capability of Hyper SuprimeCam (HSC). The prime focus unit of PFS called Prime Focus Instrument (PFI) provides the interface with the top structure of Subaru telescope and also accommodates the optical bench in which Cobra fiber positioners and fiducial fibers are located. In addition, the acquisition and guiding cameras (AGCs), the cable wrapper, the fiducial fiber illuminator, and viewer, the field element, and the telemetry system are located inside the PFI. The mechanical structure of the PFI was designed with special care such that its deflections sufficiently match those of the HSC’s Wide Field Corrector (WFC) so the fibers will stay on targets over the course of the observations within the required accuracy. The assembly, integration and verification of PFI was completed in 2021. The performance of PFI meets the requirements and it was delivered to Subaru telescope in June 2021. Consequently, various tests and engineering runs were carried out to calibrate the PFI and verify the performance of the PFI with the telescope.
ULTIMATE-Subaru is the next-generation facility instrument program of the Subaru Telescope which will extend the existing Subaru's wide-field survey capability to the near-infrared wavelength. The ULTIMATE-Subaru instrument suite includes Ground-Layer Adaptive Optics (GLAO) and wide-field near-infrared instruments, aiming to provide similar to 0.2 arcsec image size at K band (2.2 mu m) over 20 arcmin diameter field of view at the Cassegrain focus. The planned first light instrument is a Wide-Field Imager (WFI), which covers a 14 x 14 square arcmin field of view from 0.9 to 2.5 mu m in wavelength. GLAO and WFI are currently in the final design phase, aiming to start the commissioning observations at the telescope in 2028. In parallel to the development for ULTIMATE wide-field instruments, there are ongoing activities to develop a narrow-field wide-band spectrograph (NINJA) together with a Laser Tomography AO system (ULTIMATE-START) utilizing the Adaptive Secondary Mirror and the Laser Guide Star Facility being developed for the GLAO system. In this presentation, an overview of the ULTIMATE-SUBARU instruments, their current status, and future prospects will be presented.
The Mid-infrared ELT Imager and Spectrograph (METIS) is one of the first light instruments for the Extremely Large Telescope (ELT) and will cover the thermal- and mid-infrared (3-13 mu m). With the single conjugate adaptive optics (SCAO) system, it will enable high contrast imaging and integral field unit (IFU) spectroscopy (R similar to 100 000) at the diffraction limit of the ELT. Inside the METIS cryostat, it has a modular design and is composed of the common fore optics (CFO), the imager (IMG), the SCAO, and the L and M band integral field spectrograph (LMS). The components are cooled down to around 60K, or lower for the detectors, during the operation to reduce the background. In the CFO of METIS, four wheels are inserted in the optical path including the atmospheric dispersion corrector ( ADC) wheel, the pupil plane one (PP1) wheel, the focal plane two (FP2) wheel and the LMS pickoff wheel. The PP1 wheel and the ADC wheel are located near the first pupil plane while the other two wheels are at the second focal plane. These wheels accommodate the optics, slits, masks and filters for various operation modes of METIS. In each wheel, common cartridges are designed to hold the optical elements to facilitate an easy exchange between them. High positioning repeatability is required for some of the optics. We will report the design and the initial integration and tests of the wheels in this paper.
ULTIMATE-Subaru is a next facility instrumentation program of the Subaru Telescope. The goal of this project is to extend the wide-field capability of the Subaru to near-infrared (NIR), by developing a wide-field ground-layer adaptive optics (GLAO) system and wide-field NIR instruments. The GLAO system will uniformly improve the image quality up to 20-arcmin field of view in diameter by correcting for the ground-layer turbulence. The expected image quality after the GLAO correction is FWHM~0".2 in K-band under moderate seeing conditions. In this presentation, we present preliminary design overview of the GLAO system at the Cassegrain focus, which consist of an Adaptive Secondary Mirror, NGS and LGS wavefront sensor system, a laser guide star facility, and control system. We also present the prototyping activities to validate the selected design of the GLAO system.
The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber spectrograph designed for the prime focus of the 8.2m Subaru telescope. PFS will cover 1.3 degrees diameter field with 2394 fibers to complement the imaging capability of Hyper SuprimeCam (HSC). The prime focus unit of PFS called Prime Focus Instrument (PFI) provides the interface with the top structure of Subaru telescope and also accommodates the optical bench in which Cobra fiber positioners and fiducial fibers are located. In addition, the acquisition and guiding cameras (AGCs), the cable wrapper, the fiducial fiber illuminator, and viewer, the field element, and the telemetry system are located inside the PFI. The mechanical structure of the PFI was designed with special care such that its deflections sufficiently match those of the HSC's Wide Field Corrector (WFC) so the fibers will stay on targets over the course of the observations within the required accuracy. The assembly, integration and verification of PFI was completed in 2021. The performance of PFI meets the requirements and it was delivered to Subaru telescope in June 2021. Consequently, various tests and engineering runs were carried out to calibrate the PFI and verify the performance of the PFI with the telescope.
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.
In this paper, we present the beginning of the last phase of the integration process of the FOCCoS subsystem, "Fiber Optical Cable and Connector System", to be installed on the Subaru telescope as part of the PFS (Prime Focus Spectrograph) project [01]. FOCCoS consists of the 3 cables (A, B and C) to integrate and operate the instruments easily [02]. At the present stage, we are about to complete the integration of the 3 cables by building Cable B that intermediates the telescope’s light gathering and light output devices for the spectrographs. Cable B, which is ~55m long, is subdivided into 4 units. Each unit has 600 optical fibers inserted into segmented tubes that are helically stranded around the tensile core element and inserted into a flexible metal conduit, which was made by industrial process. The construction of Cable B unit involves a coherent fiber distribution for a required mapping between the light collecting ends and the output ends positioned on the slits. Multi-fiber connector bench, strain relief boxes, and connection monitoring fiber devices are being built as part of subsystem integration process. Specific FRD measurement procedures for Cable B have been fully developed and implemented. The measurements are so far indicating similarly good results to those obtained in the evaluation of fibers from Cables A and C. For Cable B, FRD of some fibers has been traced to monitor the impact of the integration process.
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.
Results of a conceptual design study of ULTAIMTE-Wide Field Imager (WFI) is presented. ULTIMATE-WFI is a near-infrared wide-field imager for the ground-layer adaptive optics system of the Subaru telescope (ULTIMATE-Subaru) which realizes a 0.'' 2 seeing size over 20'diameter at the Cassegrain focus utilizing a deformable 2ndry mirror. WFI has a 15.'7x 15.'7 FoV with a wavelength coverage of 0.9-2.5 mu m. The FoV is covered by four identical optics, each having a square field lens with 226mm on a side. Its effective FoV is 7.'2 on a side, and is covered by a HAWAII-4RG array detector with a pixel scale of 0.'' 11/pix. Effective FoV will be 14.'4x14.'4 or 207 square' in total. Spot sizes at a detector plane are less than 0.'' 1 over the wavelength coverage. Due to the large FoV, vignetting by the telescope structure occurs and an additional cold stop is necessary to block their thermal emission, which causes similar to 80% vignetting at the edge of the FoV. All the optics are contained in a cylindrical structure to be installed on the Cassegrain focus of the telescope, and kept under cryogenic temperature except for the field lenses. Gravitational deformation will be smaller than 1mm, and may have negligible impact on the final image quality.
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.
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 1.6-2.7A. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project is now going into the construction phase aiming at undertaking system integration in 2017-2018 and subsequently carrying out engineering operations in 2018-2019. This article gives an overview of the instrument, current project status and future paths forward.
The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber spectrograph design for the prime focus of the 8.2m Subaru telescope. PFS will cover 1.3 degree diameter field with 2394 fibers to complement the imaging capability of Hyper SuprimeCam (HSC). The prime focus unit of PFS called Prime Focus Instrument (PFI) provides the interface with the top structure of Subaru telescope and also accommodates the optical bench in which Cobra fiber positioners are located. In addition, the acquisition and guiding cameras (AGCs), the optical fiber positioner system, the cable wrapper, the fiducial fibers, illuminator, and viewer, the field element, and the telemetry system are located inside the PFI. The mechanical structure of the PFI was designed with special care such that its deflections sufficiently match those of the HSC's Wide Field Corrector (WFC) so the fibers will stay on targets over the course of the observations within the required accuracy. In this report, the latest status of PFI development will be given including the performance of PFI components, the setup and performance of the integration and testing equipment.
We report on the multi-wavelength identification of the X-ray sources found in the Subaru-XMM-Newton Deep Survey (SXDS) using deep imaging data covering the wavelength range between the far-UV and mid-IR (MIR). We select a primary counterpart of each X-ray source by applying the likelihood ratio method to R-band, 3.6 mu m, near-UV, and 24 mu m source catalogs as well as matching catalogs of active galactic nucleus (AGN) candidates selected in 1.4 GHz radio and i'-band variability surveys. Once candidates for Galactic stars, ultra-luminous X-ray sources in a nearby galaxy, and clusters of galaxies are removed there are 896 AGN candidates in the sample. We conduct spectroscopic observations of the primary counterparts with multi-object spectrographs in the optical and NIR; 65% of the X-ray AGN candidates are spectroscopically identified. For the remaining X-ray AGN candidates, we evaluate their photometric redshift with photometric data in 15 bands. Utilizing the multi-wavelength photometric data of the large sample of X-ray-selected AGNs, we evaluate the stellar masses, M-*, of the host galaxies of the narrow-line AGNs. The distribution of the stellarmass is remarkably constant from z=0.1 to 4.0. The relation between M-* and 2-10 keV luminosity can be explained with strong cosmological evolution of the relationship between the black hole mass and M-*. We also evaluate the scatter of the UV-MIR spectral energy distribution (SED) of the X-ray AGNs as a function of X-ray luminosity and absorption by the nucleus. The scatter is compared with galaxies which have redshift and stellarmass distributionmatched with the X-ray AGN. The UV-NIR (near-IR) SEDs of obscured X-ray AGNs are similar to those of the galaxies in the matched sample. In the NIR-MIR range, the median SEDs of X-ray AGNs are redder, but the scatter of the SEDs of the X-ray AGN broadly overlaps that of the galaxies in the matched sample.
The PFS is a multi-object spectrograph fed by 2394 fibers at the prime focus of Subaru telescope. Since the F/# at the prime focus is too fast for the spectrograph, we designed a small concave-plano negative lens to be attached to the tip of each fiber that converts the telescope beam (F/2.2) to F/2.8. We optimized the lens to maximize the number of rays that can be confined inside F/2.8 while maintaining a 1.28 magnification. The microlenses are manufactured by glass molding, and an ultra-broadband AR coating (<1.5% for λ = 0.38 - 1.26μm) will be applied to the front surface.
We present a stellar mass-metallicity relation at z similar to 1.4 with an unprecedentedly large sample of similar to 340 star-forming galaxies obtained with Fibre Multi-Object Spectrograph (FMOS) on the Subaru Telescope. We observed K-band selected galaxies at 1.2 < z(ph) < 1.6 in the Subaru XMM-Newton Deep Survey/Ultra Deep Survey fields with M-* >= 10(9.5) M-circle dot, and expected F(H alpha) >= 5 x 10(-17) erg s(-1) cm(-2). Among the observed similar to 1200 targets, 343 objects show significant H alpha emission lines. The gas-phase metallicity is obtained from [N ii] lambda 6584/H alpha line ratio, after excluding possible active galactic nuclei. Due to the faintness of the [N ii] lambda 6584 lines, we apply the stacking analysis and derive the mass-metallicity relation at z similar to 1.4. Our results are compared to past results at different redshifts in the literature. The mass-metallicity relation at z similar to 1.4 is located between those at z similar to 0.8 and z similar to 2.2; it is found that the metallicity increases with decreasing redshift from z similar to 3 to z similar to 0 at fixed stellar mass. Thanks to the large size of the sample, we can study the dependence of the mass-metallicity relation on various galaxy physical properties. The average metallicity from the stacked spectra is close to the local Fundamental Metallicity Relation (FMR) in the higher metallicity part but greater than or similar to 0.1 dex higher in metallicity than the FMR in the lower metallicity part. We find that galaxies with larger E(B - V), B - R and R - H colours tend to show higher metallicity by similar to 0.05 dex at fixed stellar mass. We also find relatively clearer size dependence that objects with smaller half-light radius tend to show higher metallicity by similar to 0.1 dex at fixed stellar mass, especially in the low-mass part.
FOCCoS, "Fiber Optical Cable and Connector System" has the main function of capturing the direct light from the focal plane of Subaru Telescope using optical fibers, each one with a microlens in its tip, and conducting this light through a route containing connectors to a set of four spectrographs. The optical fiber cable is divided in 3 different segments called Cable A, Cable B and Cable C. Multi-fibers connectors assure precise connection among all optical fibers of the segments, providing flexibility for instrument changes. To assure strong and accurate connection, these sets are arranged inside two types of assemblies: the Tower Connector, for connection between Cable C and Cable B; and the Gang Connector, for connection between Cable B and Cable A. Throughput tests were made to evaluate the efficiency of the connections. A lifetime test connection is in progress. Cable C is installed inside the PFI, Prime Focus Instrument, where each fiber tip with a microlens is bonded to the end of the shaft of a 2-stage piezo-electric rotatory motor positioner; this assembly allows each fiber to be placed anywhere within its patrol region, which is 9.5mm diameter.. Each positioner uses a fiber arm to support the ferrule, the microlens, and the optical fiber. 2400 of these assemblies are arranged on a motor bench plate in a hexagonal-closed-packed disposition. All optical fibers from Cable C, protected by tubes, pass through the motors' bench plate, three modular plates and a strain relief box, terminating at the Tower Connector. Cable B is permanently installed at Subaru Telescope structure, as a link between Cable C and Cable A. This cable B starts at the Tower Connector device, placed on a lateral structure of the telescope, and terminates at the Gang Connector device. Cable B will be routed to minimize the compression, torsion and bending caused by the cable weight and telescope motion. In the spectrograph room, Cable A starts at the Gang Connector, crosses a distribution box and terminates in a slit device. Each slit device receives approximately 600 optical fibers, linearly arrayed in a curve for better orientation of the light to the spectrograph collimator mirror. Four sets of Gang Connectors, distribution boxes and Slit devices complete one Cable A. This paper will review the general design of the FOCCoS subsystem, methods used to manufacture the involved devices, and the needed tests results to evaluate the total efficiency of the set.
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber spectrograph with 2394 science fibers, which are distributed in 1.3 degree diameter field of view at Subaru 8.2-meter telescope. The simultaneous wide wavelength coverage from 0.38 um to 1.26 um, with the resolving power of 3000, strengthens its ability to target three main survey programs: cosmology, Galactic archaeology, and galaxy/AGN evolution. A medium resolution mode with resolving power of 5000 for 0.71 um to 0.89 um also will be available by simply exchanging dispersers. PFS takes the role for the spectroscopic part of the Subaru Measurement of Images and Redshifts project, while Hyper Suprime-Cam works on the imaging part. To transform the telescope plus WFC focal ratio, a 3-mm thick broad-band coated glass-molded microlens is glued to each fiber tip. A higher transmission fiber is selected for the longest part of cable system, while one with a better FRD performance is selected for the fiber-positioner and fiber-slit components, given the more frequent fiber movements and tightly curved structure. Each Fiber positioner consists of two stages of piezo-electric rotary motors. Its engineering model has been produced and tested. Fiber positioning will be performed iteratively by taking an image of artificially back-illuminated fibers with the Metrology camera located in the Cassegrain container. The camera is carefully designed so that fiber position measurements are unaffected by small amounts of high special-frequency inaccuracies in WFC lens surface shapes. Target light carried through the fiber system reaches one of four identical fast-Schmidt spectrograph modules, each with three arms. Prototype VPH gratings have been optically tested. CCD production is complete, with standard fully-depleted CCDs for red arms and more-challenging thinner fully-depleted CCDs with blue-optimized coating for blue arms.
The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber spectrograph design for the prime focus of the 8.2m Subaru telescope. PFS will cover 1.3 degree diameter field with 2394 fibers to complement the imaging capability of Hyper SuprimeCam (HSC). The prime focus unit of PFS called Prime Focus Instrument (PFI) provides the interface with the top structure of Subaru telescope and also accommodates the optical bench in which Cobra fiber positioners are located. In addition, the acquisition and guiding (A&G) cameras, the optical fiber positioner system, the cable wrapper, the fiducial fibers, illuminator, and viewer, the field element, and the telemetry system are located inside the PFI. The mechanical structure of the PFI was designed with special care such that its deflections sufficiently match those of the HSC's Wide Field Corrector (WFC) so the fibers will stay on targets over the course of the observations within the required accuracy.