Prime Focus Spectrograph (PFS): the Prime Focus Instrument

Shiang Yu Wang, Masahiko Kimura, Chi Hung Yan, Chang Yin-Chang, Shu Fu Hsu, Jennifer Karr, Hsin Yo Chen, Pin Jie Huang, Chih Yi Wen, Richard C.Y. Chou, Hung Hsu Ling, Naoyuki Tamura, Yuki Moritani, Julien Rousselle, Hiroshige Yoshida, Shintaro Koshida, Naruhisa Takato, Dan J. Reiley, Mitsuko Roberts, James E. GunnCraig Loomis, Robert H. Lupton, Neven Caplar, Hassan Siddiqui, Decio Ferreira, Leandro Henrique dos Santos, Ligia Souza Oliveira, Antonio Cesar de Oliveira, Lucas Souza Marrara, Maximilian Fabricius, Graham J. Murray

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


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.

Original languageEnglish (US)
Title of host publicationGround-based and Airborne Instrumentation for Astronomy IX
EditorsChristopher J. Evans, Julia J. Bryant, Kentaro Motohara
ISBN (Electronic)9781510653498
StatePublished - 2022
EventGround-based and Airborne Instrumentation for Astronomy IX 2022 - Montreal, Canada
Duration: Jul 17 2022Jul 22 2022

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceGround-based and Airborne Instrumentation for Astronomy IX 2022

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


  • Prime Focus
  • guiding camera
  • mechanical structure
  • multi-fiber
  • spectrograph


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