COSMOS Observations: Subaru

The Subaru telescope (Mauna Kea, HI) has played a major role in the COSMOS project and continues to observe the field. We list here several prior and ongoing surveys of the COSMOS field that have been performed with Subaru and the Suprime-Cam wide-field imager.

• Subaru-COSMOS imaging survery (z' filter)
  • 10 nights (2008) with S-Cam to cover the entire field with the z' broadband filter
  • Team: H. Furusawa et al.
  • Sensitivity: Limiting mag. = 27.5 AB (2" phi & 5 sigma; accounting for new CCD sensitivity)
  • Goals:
    • search for Lyman Break Galaxies (LBGs) at z=6 (Mauro Giavalisco et al.)
    • search for z' dropouts
  • Status: proposal submitted
  
  
• Subaru-COSMOS imaging survery (NB921 filter)
  • 5 nights (2008) with S-Cam to cover the entire field with the NB921 narrowband filter
  • Sensitivity: Limiting mag. = 25.5 AB (2" phi & 5 sigma); maybe much deeper because new red-sensitive CCDs will be available
  • Goals:
    • search for Lyman-alpha emitters (LAEs) at z=6.6
    • also study early large-scale structure formation together with COSMOS LAE data at different redshifts
  • Team: Y. Taniguchi et al.
  • Status: proposal submitted
  
  
• Subaru-COSMOS imaging survey (COSMOS-21: intermediate and narrow band filters)
  • 12 nights (Jan-Mar '05) with S-Cam to cover the entire 2 square degree field in 13 Intermediate-band and 3 narrow-band filters covering the wavelength range ~4000-10000 Å
  • Goals:
    • to use the intermediate-band filters to improve the photometric redshifts for all galaxies
    • to search for quasars
    • to search for both Lyman-alpha emitters and Lyman break galaxies from z=2.5 to 5.8 (LAE/LBG ratio as a function of z)
    • the above two issues are also discussed in terms of star & black hole formation history in galaxies
  • Team: Y. Taniguchi (PI, Tohoku) + 16 others (8 nights); N. Scoville (PI) + 8 others (4 nights)
  • Status: Data obtained, reduced, and included in latest photometry catalog.
  
  
• Subaru-COSMOS imaging survey (broad band filters)
  • 10 nights (Jan-Feb '04) with S-Cam to cover the entire 2 square degree field in 5 broad band filters (B,V,r+,i+,z+)
  • Sensitivity: (AB, 5 sigma): B (27.4), V (27.2), r+ (26.9), i+ (26.9), z+ (25.6)
  • Data products:
    1. photometric, flux calibrated images (.05mag rms) with absolute astrometry ( 0.1xACS pixel) over the full COSMOS field
    2. a trial photometric redshift catalog of nearly one million sources obtained by combining these S-Cam data with U-band data from CFHT/Megacam and Ks-band data from NOAO
  • Goals:
    • the secure identification of over 10⁶ galaxies with I < 26 mag
    • determination of accurate SEDs to produce a large catalog of photometric redshifts
    • initial identification of clusters out to z ~ 3
  • Team: Y. Taniguchi (PI, Tohoku) + 16 others
  • Status: Data obtained, reduced, and included in latest photometry catalog.

Updated June 2008.