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| Subaru/FOCAS | |
|---|---|
| Name | Subaru/FOCAS |
| Operator | Subaru Telescope |
| Location | Mauna Kea |
| Aperture | 8.2 m |
| Instrument | Faint Object Camera and Spectrograph |
| First light | 2000 |
| Wavelength | Optical |
Subaru/FOCAS Subaru/FOCAS is a focal-plane instrument mounted on the Subaru Telescope on Mauna Kea, designed for optical imaging and spectroscopy of faint sources. It serves programs spanning extragalactic surveys, stellar astrophysics, and Solar System studies, supporting observers from institutions such as the National Astronomical Observatory of Japan and international partners like the University of Hawaii and the Smithsonian Astrophysical Observatory. The instrument interfaces with facility systems including the Subaru Prime Focus Unit and benefit programs linked to observatories like Keck Observatory and the Gemini Observatory.
FOCAS was developed to perform low- to medium-resolution spectroscopy and imaging for targets discovered by projects such as the Sloan Digital Sky Survey, the Hubble Space Telescope deep fields, and surveys by the Pan-STARRS project. It was commissioned alongside instruments and facilities like the Subaru Prime Focus Camera, the Hyper Suprime-Cam, the Suprime-Cam, and the Infrared Camera and Spectrograph used by collaborations from institutions such as the University of Tokyo, Kyoto University, and Tokyo Institute of Technology. The instrument contributed to follow-up efforts for transients identified by surveys including the Zwicky Transient Facility, the Catalina Real-Time Transient Survey, and the All-Sky Automated Survey for SuperNovae, complementing spectrographs on the Very Large Telescope and the Gran Telescopio Canarias.
FOCAS integrates an optical bench, collimator, camera optics, and detector systems reminiscent of designs used in instruments like the Low Resolution Imaging Spectrometer, the Echellette Spectrograph and Imager, and the DEep Imaging Multi-Object Spectrograph. Core components include a multi-slit mask unit influenced by mask technologies from the Multi-Object Spectrometer For Infra-Red Exploration, a grism suite comparable to that on the FOcal Reducer and low dispersion Spectrograph, and CCD detectors analogous to devices in the Advanced Camera for Surveys, the Wide Field Camera 3, and instruments at the Subaru HDS. Mechanical systems and electronics were developed with engineering practices shared by groups at institutions such as the National Astronomical Observatory of Japan, the Academia Sinica Institute of Astronomy and Astrophysics, and the Max Planck Institute for Astronomy. The optical path includes elements comparable to dichroics used on the Keck LRIS, filters similar to those employed by the Pan-STARRS telescopes, and calibration lamps found in spectrographs at the European Southern Observatory and the Carnegie Observatories.
FOCAS offers imaging, long-slit spectroscopy, multi-object spectroscopy, and polarimetric modes with performance parameters used for programs led by teams from Harvard-Smithsonian Center for Astrophysics, Princeton University, and the California Institute of Technology. Typical resolving powers and sensitivity limits are employed by observers studying targets identified by missions such as the Chandra X-ray Observatory, the Spitzer Space Telescope, and the Galaxy Evolution Explorer, and cross-referenced with data from the Two Micron All Sky Survey, the Wide-field Infrared Survey Explorer, and the Gaia mission. Comparative performance assessments reference instruments like the Subaru HDS, the Keck MOSFIRE, the VLT FORS2, and the Gemini GMOS, and are used in proposals submitted to time allocation committees at organizations including the International Astronomical Union and national funding agencies such as the Japan Society for the Promotion of Science.
Calibration strategies for FOCAS use flat-field lamps, arc lamps, and spectrophotometric standards similarly to pipelines developed for the Sloan Digital Sky Survey, the Hubble Legacy Archive, and the European Southern Observatory archives. Data reduction approaches have been influenced by software from the Image Reduction and Analysis Facility, the Astropy project, IRAF-based routines, and bespoke pipelines produced by groups at the National Astronomical Observatory of Japan, the University of Cambridge Institute of Astronomy, and the Leiden Observatory. Flux calibration and wavelength solutions tie into standards maintained by organizations such as the National Institute of Standards and Technology, the Space Telescope Science Institute, and the International Astronomical Union working groups.
FOCAS enabled spectroscopic confirmation of high-redshift galaxies discovered in deep fields imaged by the Hubble Space Telescope, Subaru Deep Field, and the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, contributing to literature involving collaborations across institutions like the Kavli Institute for the Physics and Mathematics of the Universe, the Max Planck Society, and the Carnegie Institution for Science. Science outcomes include redshift surveys complementing the Galaxy And Mass Assembly project, studies of active galactic nuclei relevant to results from the Sloan Digital Sky Survey and the COSMOS survey, and transient classifications feeding programs associated with the LIGO Scientific Collaboration and the IceCube Neutrino Observatory. FOCAS observations supported stellar population analyses in Local Group targets such as the Andromeda Galaxy, the Large Magellanic Cloud, and the Small Magellanic Cloud, and Solar System spectroscopy connected to campaigns by the Minor Planet Center and the International Astronomical Union Minor Planet Center.
Operational support for FOCAS has been coordinated by the Subaru Telescope staff, the National Astronomical Observatory of Japan, and collaborating instrument teams at universities including the University of Hawaii and Kyoto University. Upgrades and maintenance cycles have followed practices from facility programs at the European Southern Observatory, the National Optical Astronomy Observatory, and the Subaru instrument program, with potential modernization paths taking cues from developments at the Keck Observatory, the Gran Telescopio Canarias, and the Vera C. Rubin Observatory. Support activities involve scheduling with time allocation committees at national observatories, technical work by engineering groups at organizations such as Mitsubishi Electric and Hamamatsu Photonics, and training initiatives connected to the International Astronomical Union and the Asia-Pacific Regional Office.
Category:Subaru Telescope instruments