Subaru telescope: Current performances and future upgrade plans

Tomonori Usuda, Naruhisa Takato, Tomio Kanzawa, Akihiko Miyashita, Fumihiro Uraguchi, Tomio Kurakami, George Kosugi, Saeko S. Hayashi, Masayuki Akiyama, Noboru Itoh, Satoru Negishi, Shinji Sugahara, Wataru Tanaka

Research output: Contribution to journalConference articlepeer-review

8 Citations (Scopus)


The Subaru Telescope has been stably operated with high image quality since common use began in December 2000. We have updated the following items in order to achieve further improvement of observation efficiency, image quality, and tracking. 1. High reflectivity of mirrors. The reflectivity of the primary mirror has been maintained, yielding 84% at 670 nm by regular CO2 cleaning (every two to three weeks). We successfully carried out the silver coating of the Infrared secondary mirror in April 2003 without over-coating. The reflectivity has been maintained at greater 98% at 1,300 nm. 2. Image Quality. Subaru telescope delivers exceptional image quality - a median image size of 0.6 arc-second FWHM in the A-band as taken by Auto-Guider Cameras at all four foci; Prime, Cassegrain, and two Nasmyth. We optimized parameters of the servo control system of the Elevation servo, reducing the amplitude of 3-8 Hz vibration mode of the telescope and improving image quality when using the Adaptive Optics (AO) system. 3. Acquisition Guiding. Dithering time was shortened by updating the control software. The slit viewer camera for HDS and the fiber bundle for FMOS are available for acquisition guiding in addition to Auto-Guider Cameras. 4. New instruments. We are developing a new prime focus unit for FMOS and will start functional tests in 2005. Moreover, we have started to prepare new interfaces and facilities for FMOS and the new 188 element AO natural/laser guide star system. The focus switching time will be shortened by updating the hardware of the IR and Cassegrain Optical secondary mirrors from September 2004, reducing it to 10 minutes to switch the focus between Cassegrain and Nasmyth foci.

Original languageEnglish
Pages (from-to)278-287
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
Issue numberPART 1
Publication statusPublished - 2004
EventGround-based Telescopes - Glasgow, United Kingdom
Duration: 2004 Jun 212004 Jun 25


  • Astronomy
  • Ground based Large Telescope
  • Subaru Telescope


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