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.
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 (NIR) wavelength. The ULTIMATE-Subaru instrument suite includes Ground-Layer Adaptive Optics (GLAO) and wide-field near-infrared instruments, aiming to provide ~ 0.2 arcsec image size at K band (2.2 micron) 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 in NIR wavelength. The instrument development is led by Subaru/NAOJ in collaboration with ANU, Tohoku University, ASIAA, and the University of Tokyo. The GLAO and WFI are currently in the final and the preliminary design phases, respectively, aiming to conduct the commissioning at the telescope in 2028. In this presentation, an overview of the ULTIMATE-SUBARU instruments, their current status, and future prospects will be presented.
ULTIMATE-Subaru is a next-generation wide-field NIR imaging camera with ground layer adaptive optics, being developed for the Subaru telescope. Here we present the current sensitivity performance estimates for the instrument. In the ideal conditions of good (25%) seeing with GLAO, airmass of 1 and an hour exposure time, we reach 5σ point source depths of 25.6, 25.5, 25.2 and 25.4 mags in YJHKs respectively. The ULTIMATE sensitivities show an improvement of 0.4−0.6 mag over MOIRCS in broad-band filters under the same observing conditions (without GLAO). With GLAO there is a further improvement of 0.2∼0.4 mags in depth across all bands compared to natural seeing, in addition to the significant enhancement in image quality, i.e. FWHM up to a factor of 2 over natural seeing. We have also modeled the fractional noise contribution in the NIR from sky background, telescope thermal background, moon background and read noise. We find that sky background is the dominant source of noise across most NIR bands, apart from the K-band, where the thermal emission from the telescope becomes a significant source of noise. Our results indicate that K-band observations using ULTIMATE-Subaru with GLAO under ideal observing conditions could potentially reach sensitivities comparable to those of the Roman telescope, given that instrument thermal emission remains an important noise component in both ground and space telescopes at this wavelength.
We have undertaken the development of high-efficiency and wide spectral coverage grisms for MOIRCS, the near-infrared imager and multi-object spectrograph at the Subaru Telescope. Our prior medium-resolution gratings, incorporating Volume Phase Holographic (VPH) gratings, offered very high efficiency at their peak. However, their narrow transmission curves significantly limited their scientific application, especially in the MOS mode. In response to the demand for better medium-dispersion grisms from the community, we developed new high-sensitivity and wide-spectral-coverage grisms (“LightSmyth grisms”) for the J & H windows in 2019. It was a great success, with significant improvement on both peak efficiency and the wide bandwidth coverage. Following this achievement, we embarked on the development of a comparable medium-dispersion grism for the K-band (“VB-K grism”), incorporating our proprietary Volume-Binary (VB) grating. The fabrication was completed by the summer of 2023. The basic performance test inside the dome confirmed its excellent performance as planned. The first scientific use by open-use observers was achieved in March 2024. A more detailed on-sky performance evaluation is scheduled this summer.
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.
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.
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.
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 (ULTIMATESubaru) which realizes a 0. 002 seeing size over 200diameter at the Cassegrain focus utilizing a deformable 2ndry mirror. WFI has a 15. 07×15. 07 FoV with a wavelength coverage of 0.9–2.5µm. The FoV is covered by four identical optics, each having a square field lens with 226mm on a side. Its effective FoV is 7. 02 on a side, and is covered by a HAWAII-4RG array detector with a pixel scale of 0. 0011/pix. Effective FoV will be 14. 04×14. 04 or 2070 in total. Spot sizes at a detector plane are less than 0. 001 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 ~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.
ULTIMATE-Subaru is a next large facility instrument project at Subaru telescope. We will develop a 14x14 sq. arcmin wide-field near-infrared (NIR) imager and a multi-object spectrograph with the aid of a ground- layer adaptive optics system (GLAO), which will uniformly improve the seeing by a factor of 2 over a wide field of view up to ~20 arcmin in diameter. We have developed system modeling of the GLAO and wide-field NIR instruments to define the system level requirements flow down from science cases and derive the system performance budgets based on the GLAO end-to-end numerical simulation and optical system models of the telescope and wide-field NIR science instruments. In this paper, we describe the system performance modeling of ULTIMATE-Subaru and present an overview of the requirements flow down.
The Simultaneous-color Wide-field Infrared Multi-object Spectrograph (SWIMS) is one of the 1st generation facility instruments for the University of Tokyo Atacama Observatory (TAO) 6.5 m telescope currently being constructed at the summit of Cerro Chajnantor (5,640 m altitude) in northern Chile. SWIMS has two optical arms, the blue arm covering 0.9–1.4 µm and the red 1.4–2.5 µm, by inserting a dichroic mirror into the collimated beam, and thus is capable of taking images in two filter-bands simultaneously in imaging mode, or whole nearinfrared (0.9–2.5 µm) low-to-medium resolution multi-object spectra in spectroscopy (MOS) mode, both with a single exposure. SWIMS was carried into Subaru Telescope in 2017 for performance evaluation prior to completion of the construction of the 6.5 m telescope, and successfully saw the imaging first light in May 2018 and MOS first light in Jan 2019. After three engineering runs including the first light observations, SWIMS has been accepted as a new PI instrument for Subaru Telescope from the semester S21A until S22B. In this paper, we report on details of on-sky performance of the instrument evaluated during the engineering observations for a total of 7.5 nights.
ULTIMATE-Subaru is a next large facility instrument project at Subaru telescope. We will develop a 14x14 arcmin2 wide-field near-infrared (1.0-2.5μm) imager and a multi-object spectrograph with the aid of a ground- layer adaptive optics system (GLAO), which will uniformly improve the seeing by a factor of 2 over a wide field of view up to ~20 arcmin in diameter. The expected spatial resolution by the GLAO correction is about 0.2 arcsec FWHM in K-band under moderate seeing conditions at Subaru telescope. ULTIMATE-Subaru will provide a unique capability to realize wide-field and high spatial resolution survey observations in near infrared in the era of TMT. In this paper, we introduce the project overview including the GLAO and near-infrared instrument conceptual design. We also describe the future wide-field strategy at Subaru telescope with ULTIMATE-Subaru together with HSC and PFS.
We report on the conceptual design study done for the Ground Layer Adaptive Optics system of the ULTIMATE-Subaru project. This is an ambitious instrument project, providing GLAO correction in a square field of view of 14 arcmin on a side, aiming to deliver improved seeing at the near infrared wavelength. Its client instruments are an imager and multi-IFU spectrograph at Cassegrain and a Multi-Object spectrograph at Nasmyth. In this paper, we introduce the ULTIMATE-Subaru project overview and its science case and report the results of the GLAO performance prediction based on the numerical simulation and conceptual design of the wavefront sensor system.
The Simultaneous-color Wide-field Infrared Multi-object Spectrograph, SWIMS, is a first-generation near-infrared instrument for the University of Tokyo Atacama Observatory (TAO) 6.5m Telescope now being constructed in northern Chile. To utilize the advantage of the site that almost continuous atmospheric window appears from
0.9 to 2.5 μm, the instrument is capable of simultaneous two-color imaging with a field-of-view of 9.′6 in diameter or λ/▵λ 1000 multi-object spectroscopy at 0.9–2.5 μm in a single exposure. The instrument has been trans- ported in 2017 to the Subaru Telescope as a PI-type instrument for carrying out commissioning observations before starting science operation on the 6.5m telescope. In this paper, we report the latest updates on the instrument and present preliminary results from the on-sky performance verification observations.
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