Observing
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FMOS Instrument Parameters
Fiber positioner system "Echidna" (see this page for more details) |
Field of view |
30' diameter (circular FOV at the prime focus) |
Fiber diameter |
1.2 arcsec (100 microns) |
Fiber configuration time |
~13 minutes |
Patrol field of each spine |
87 arcsec in radius (i.e. 6.6 sq. arcmin in area) |
Minimal spacing between neighboring spines |
12 arcsec |
Fiber positioning error |
0.2 arcsec rms(1) |
Spectrograph (see this page for more details) |
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Low Resolution (LR) |
High Resolution (HR)(5) |
Spectral coverage |
0.9-1.8 μm |
0.92-1.12 μm ("J-short")
1.11-1.35 μm ("J-long")
1.40-1.60 μm ("H-short")
1.45-1.67 μm ("H-short prime")
1.60-1.80 μm ("H-long") |
Spectral resolution |
R=600 |
R=2200 |
Dispersion |
~5 A/pix |
~1 A/pix |
Image quality |
FWHM = 4-5 pix |
Number of fibers to be extracted as spectra |
197(IRS1)(2)
200 (IRS2) |
Detector system |
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IRS1 |
IRS2 |
Detector array |
HAWAII-2 (Sci #55) |
HAWAII-2 (Sci #90) |
Array format |
2048 x 2048 |
Pixel size |
18 μm |
Readout elesctronics |
TUFPAC+Messia V |
SDSU IR Gen III |
Readout time (= Minimum exposure time) |
~17 sec |
~6 sec |
Gain |
~2.0 e-/ADU |
~3.8 e-/ADU |
Dark current |
< 0.1 e-/sec/pix |
< 0.1 e-/sec/pix |
Total background(3) |
~0.2 e-/sec/pix |
~0.2 e-/sec/pix |
Readout noise(4) |
~30 e-/pix rms |
~15 e-/pix rms |
Linearity |
<1% up to 40,000 ADU |
~1% up to 20,000 ADU |
(1) This error is based on the measured displacements of the fiber
positions from the stars in an open cluster in an engineering
observation. Namely, this is a combination of the error in astrometry
(the coordinates of the stars were from the UCAC2 catalog) and the
purely mechanical error of Echidna in fiber positioning (~10 μm,
corresponding to 0.1 arcsec).
(2) The spectra from the three fibers located near the edge of the FOV
are focused outside the detector.
(3) This shows the background level including thermal radiation and
stray light as well as the dark current of the detector.
(4) These values are error per Fowler sampling.
(5) The wavelength coverage has been changed significantly as of May 2012.
Last updated: May 7, 2012
Copyright© 2000-2012 Subaru Telescope, NAOJ. All rights reserved.
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