U-band Instrument Specification

Specification

  • detector: CMOS Gpixel GSENSE 400 BSI-UV: specification [pdf]
    • 2048 x 2048 pixel (11 um/pixel)
    • readout noise: 1.4 e-/pix
    • camera module: FLI KL400BI w/ G1 shutter, peltier cooler
  • optics: designed for 1.5m Kanata telescope (Hiroshima University)
    • @2nd Nasmyth focus (no rotator)
    • optimized for 300-400nm
    • F/10.0
    • field-of-view: 5.0 x 5.0 arcmin2
    • pixel scale: 0.146 arcsec / pixel
    • designed by PhotoCross
  • filters
    • u, g, r, u-short, u-long
    • transmission curve (filter only): figure
  • total throughput at airmass=1.2 (figure, ascii file)
    • w/o filters
      • 0.04 at 310nm
      • 0.18 at 350nm
      • 0.30 at 400nm
    • w/ u-band filter
      • 0.09 at 330nm
      • 0.13 at 350nm
      • 0.14 at 360nm (peak)
      • 0.04 at 380nm
  • sensitivity by assuming nominal sky brightness (AB mag)
    • S/N=5: 18.0-19.0 (t=10 sec), 19.0-20.0 (t=100 sec)
    • S/N=20: 16.5-17.5 (t=10 sec), 18.0-19.0 (t=100 sec)
  • stellar density in u-band
    • statistics from SDSS (i.e., high galactic latitude) u-band data: figure
  • maximum exposure time for a single exposure / image motion
    • no instrument/image rotator available at 2nd Nasmyth focus of Kanata telescope
    • ~20-30 sec in most cases (background limit even in nominal sky brightness assumption above)
    • depending on hour angle and object’s Declination
    • figure
  • differential atmospheric dispersion
  • Kanata telescope
    • tracking accuracy: 1-2 arcsec / 5 minutes

Schedule (as of June 23, 2023)

  • first light at Kanata telescope in FY2023 winter