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.
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 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.
The Prime Focus
Spectrograph (PFS) survey will target the same patch of sky from several dozens
to 100 times. The problem of allocating PFS' 2394 fibers to objects over many
visits of a field is a highly non-trivial optimization problem. Our network
flow approach models the fiber allocation as a generalized network
min-cost/max-flow problem.
This methodology is inspired by SDSS, but extends this to address the
variety of requirements of the the PFS survey. Ultimately, we
solve the network flow through linear programming. This generally provides
a very good solution in reasonable amounts of time and can give a clear
quantitative measure of just “how good it is”. It allows us to define an arbitrary number of target classes with different
weights, to enforce constraints on the target distribution,
and to put caps to the number of observed objects per class.
We will present the methodology and the implementation of our approach.
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 a 1.3 degree diameter field with 2394 fibers to complement the imaging capabilities of Hyper SuprimeCam. To retain high throughput, the final positioning accuracy between the fibers and observing targets of PFS is required to be less than 10 µ m. The metrology camera system (MCS) serves as the optical encoder of the fiber positioners for configuring of fibers. The MCS locates at the Cassegrain focus of the Subaru telescope to cover the whole focal plane with one 50M pixel CMOS sensor. The information from MCS will be fed into the fiber positioner control system for closed loop control. The MCS was delivered to Subaru Observatory in Apr. 2018 and it had two engineering runs in Oct. 2018 and Aug. 2019. The 1st engineering run concluded that the original mirror supports need to be improved to provide better image quality. The newly designed mirror supports were installed before the 2nd engineering run. The 2nd engineering run result shows that the MCS overall position accuracy is better than 4μm and the image processing time is less than 4 seconds. The MCS is ready for the system integration with other PFS components.
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 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 delivery of PFI components started in 2017. After the verification of these components, the mechanical structure of the PFI is fully assembled in early 2019 and all Cobra positioners are integrated in summer 2020. A temperature controlled chamber with precise x-y scanner was setup for the verification of the fiber positioners. The testing of the target convergence performance of Cobra positioners is now in progress.
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.
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 a 1.3 degree diameter field with 2394 fibers to complement the imaging capabilities of Hyper SuprimeCam. To retain high throughput, the final positioning accuracy between the fibers and observing targets of PFS is required to be less than 10 μm. The metrology camera system (MCS) serves as the optical encoder of the fiber positioners for the configuring of fibers. MCS provides the fiber positions within a 5 microns error over the 45 cm focal plane. The information from MCS will be fed into the fiber positioner control system for the closed loop control. MCS locates at the Cassegrain focus of Subaru telescope to cover the whole focal plan with one 50M pixel Canon CMOS camera. It is a 380 mm aperture Schmidt type telescope which generates uniform spot size around 10 µm FWHM across the field for reasonable sampling of the point spreading function. An achromatic lens set is designed to remove the possible chromatic error due to the variation of the LED wavelength. Carbon fiber tubes are used to provide stable structure over the operation conditions without focus adjustments. The CMOS sensor can be read in 0.8 s to reduce the overhead for the fiber configuration. The positions of all fibers can be obtained within 0.5 s after the readout of the frame. This enables the overall fiber configuration to be less than 2 minutes. MCS is installed inside a standard Subaru Cassgrain Box. All components generate heat are located inside a glycol cooled cabinet to reduce the possible image motion due to the heat. The integration of MCS started from fall 2017 and it was delivered to Subaru in April 2018. In this report, the performance of MCS after the integration and verification process in ASIAA and the performance after the delivery to Subaru telescope are presented.
SPIRou (SpectroPolarimètre Infra-Rouge in French), is a near-infrared, fiber-fed spectropolarimeter at the CanadaFrance-Hawaii Telescope (CFHT) which gives full spectral coverage from 0.98 to 2.35 μm with a resolving power of 70,000. The main science drivers for SPIRou are (i) detecting and characterizing exoplanets around nearby M dwarfs through high-precision (1 m/s) velocimetry, and (ii) investigating the impact of magnetic fields on star/planet formation through spectropolarimetry. One of the requirements for achieving this challenging radial velocity (RV) precision is ensuring that the observed star does not move with respect to the instrument entrance aperture by more than 0.05 arcseconds RMS over the course of the observation. This is complicated by the fact that the guiding uses light from the science target so that only about 13% of the light (10% from the wings and 3% from the core) is available in seeing conditions of 0.65 arc-seconds in H band. To achieve this level of guiding accuracy, a fast guiding system has been implemented in the injection module of the instrument. This paper describes the system, its performance in tests on the sky with the CFHT since the delivery of SPIRou in January 2018, and gives comparisons to laboratory measurements and simulations.
KEYWORDS: Control systems, Telescopes, Signal to noise ratio, Spectrographs, Databases, Cameras, Point spread functions, Software development, Imaging systems, Detection and tracking algorithms
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 a 1.3-degree diameter field with 2394 fibers to complement the imaging capability of Hyper SuprimeCam (HSC). The Fiber Positioning System (FPS) is an automated system that controls the sequences for the operation of the PFS subsystems to achieve accurate positioning of the science fibers for astronomical observations. FPS will be operated continuously for 14 hours a night and accomplish the fiber positioning sequence every 15 minutes. The success rate of each alignment should be 95% or more and FPS should finish the fiber alignment procedure in 105 seconds. A fast centroid algorithm is implemented for measuring 2349 fiber spots within 1 second. In this report, the latest status of the development of FPS system will be given, including the system performance and closed-loop simulations.
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 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.
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multifiber spectrograph with 2394 science fibers distributed across a 1.3-deg diameter field of view at the Subaru 8.2-m telescope. The wide wavelength coverage from 0.38 μm to 1.26 μm, with a resolving power of 3000, simultaneously strengthens its ability to target three main survey programs: cosmology, galactic archaeology and galaxy/AGN evolution. A medium resolution mode with a resolving power of 5000 for 0.71 μm to 0.89 μm will also be available by simply exchanging dispersers. We highlight some of the technological aspects of the design. To transform the telescope focal ratio, a broad-band coated microlens is glued to each fiber tip. A higher transmission fiber is selected for the longest part of the cable system, optimizing overall throughput; a fiber with low focal ratio degradation is selected for the fiber-positioner and fiber-slit components, minimizing the effects of fiber movements and fiber bending. Fiber positioning will be performed by a positioner consisting of two stages of piezo-electric rotary motors. The positions of these motors are measured by taking an image of artificially back-illuminated fibers with the metrology camera located in the Cassegrain container; the fibers are placed in the proper location by iteratively measuring and then adjusting the positions of the motors. Target light reaches one of the four identical fast-Schmidt spectrograph modules, each with three arms. The PFS project has passed several project-wide design reviews and is now in the construction phase.
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. The metrology camera system of PFS serves as the optical encoder of the COBRA
fiber motors for the configuring of fibers. The 380mm diameter aperture metrology camera will locate at the Cassegrain
focus of Subaru telescope to cover the whole focal plane with one 50M pixel Canon CMOS sensor. The metrology
camera is designed to provide the fiber position information within 5μm error over the 45cm focal plane. The positions
of all fibers can be obtained within 1s after the exposure is finished. This enables the overall fiber configuration to be
less than 2 minutes.
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 μm to 1.26 μm, 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 μm to 0.89 μm also will be available by simply exchanging dispersers. PFS takes the role for the
spectroscopic part of the Subaru Measurement of Images and Redshifts (SuMIRe) project, while Hyper Suprime-Cam
(HSC) works on the imaging part. HSC’s excellent image qualities have proven the high quality of the Wide Field
Corrector (WFC), which PFS shares with HSC. The PFS collaboration has succeeded in the project Preliminary Design
Review and is now in a phase of subsystem Critical Design Reviews and construction.
To transform the telescope plus WFC focal ratio, a 3-mm thick broad-band coated microlens is glued to each fiber tip.
The microlenses are molded glass, providing uniform lens dimensions and a variety of refractive-index selection. After
successful production of mechanical and optical samples, mass production is now complete. Following careful
investigations including Focal Ratio Degradation (FRD) measurements, 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. After evaluating the statistics
of positioning accuracies, collision avoidance software, and interferences (if any) within/between electronics boards,
mass production will commence. 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. All optical glass blanks are now being polished. 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 active damping system against cooler vibration has been proven to
work as predicted, and spectrographs have been designed to avoid small possible residual resonances.
KEYWORDS: Stars, Calibration, Control systems, Telescopes, Spectrographs, Sensors, Control systems design, Temperature metrology, Optical benches, Lamps
SPIRou is a near-IR (0.98-2.35μm), echelle spectropolarimeter / high precision velocimeter being designed as a nextgeneration
instrument for the 3.6m Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, with the main goals of
detecting Earth-like planets around low-mass stars and magnetic fields of forming stars. The unique scientific and
technical capabilities of SPIRou are described in a series of eight companion papers. In this paper, the means of
controlling the instrument are discussed. Most of the instrument control is fairly normal, using off-the-shelf components
where possible and reusing already available code for these components. Some aspects, however, are more challenging.
In particular, the paper will focus on the challenges of doing fast (50 Hz) guiding with 30 mas repeatability using the
object being observed as a reference and on thermally stabilizing a large optical bench to a very high precision (~1 mK).μ
The Prime Focus Spectrograph (PFS) is a new multi-fiber spectrograph on Subaru telescope. PFS will cover around 1.4
degree diameter field with ~2400 fibers. To ensure precise positioning of the fibers, a metrology camera is designed to
provide the fiber position information within 5 μm error. The final positioning accuracy of PFS is targeted to be less than
10 μm. The metrology camera will locate at the Cassegrain focus of Subaru telescope to cover the whole focal plan. The
PFS metrology camera will also serve for the existing multi-fiber infrared spectrograph FMOS.
The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (SuMIRe) project has been
endorsed by Japanese community as one of the main future instruments of the Subaru 8.2-meter telescope at Mauna Kea,
Hawaii. This optical/near-infrared multi-fiber spectrograph targets cosmology with galaxy surveys, Galactic archaeology,
and studies of galaxy/AGN evolution.
Taking advantage of Subaru’s wide field of view, which is further extended with the recently completed Wide Field
Corrector, PFS will enable us to carry out multi-fiber spectroscopy of 2400 targets within 1.3 degree diameter. A
microlens is attached at each fiber entrance for F-ratio transformation into a larger one so that difficulties of spectrograph design are eased. Fibers are accurately placed onto target positions by positioners, each of which consists of two stages
of piezo-electric rotary motors, through iterations by using back-illuminated fiber position measurements with a widefield
metrology camera. Fibers then carry light to a set of four identical fast-Schmidt spectrographs with three color arms
each: the wavelength ranges from 0.38 μm to 1.3 μm will be simultaneously observed with an average resolving power
of 3000.
Before and during the era of extremely large telescopes, PFS will provide the unique capability of obtaining spectra of
2400 cosmological/astrophysical targets simultaneously with an 8-10 meter class telescope. The PFS collaboration, led
by IPMU, consists of USP/LNA in Brazil, Caltech/JPL, Princeton, and JHU in USA, LAM in France, ASIAA in Taiwan,
and NAOJ/Subaru.
The Canada-France-Hawaii Telescope (CFHT) is now operating a Wide Field Infrared Camera (WIRCam) with a 20.5' x 20.5' field of view. The camera uses a mosaic of four Rockwell HAWAII-2RG detectors enabling subsample readouts at a rate of 50Hz for guiding and fast parallel readout of 32 amplifiers per detector for science. This paper will discuss the software architecture and implementation used to optimize the scientific productivity of the instrument as well as our experience during the first semester of use.
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.