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FIES throughput ...

with the new CCD15 and bundle C

Based on observations of spectrophotometric standards in Oct 2016, with the medium/low resolution fiber (R=45000/25000, aperture 1.3/2.5 arcsec) with good seeing, the efficiency of FIES (with fiber bundle C) is indicated in the table below.
We note that the efficiency, and hence also the expected count rate, of the high-resolution fiber (R=65000, aperture 1.3 arcsec) is 0.6 times the indicated values in the table below.

Wavelength
(Å)
Efficiency
(Atm. + tel. + inst.)
Exposure time for S/N=100 per pixel for B=V=R=I=10
for low-res fiber and excellent seeing
Dispersion
(Å / pixel)
3800 0.8 % 8400 s 0.022
3950 1.5 % 4200 s 0.023
4200 2.3 % 3000 s 0.023
4400 3.1 % 2000 s 0.025
5000 5.4 % 1400 s 0.028
5300 6.3 % 1100 s 0.030
6000 9.0 % 1000 s 0.033
6500 9.7 % 900 s 0.036
7000 9.4 % 1000 s 0.039
7400 9.8 % 1000 s 0.041
8000 9.3 % 1200 s 0.045
8300 7.1 % 1500 s 0.047
8500 5.4 % 2000 s 0.048
8800 4.0 % 2700 s 0.049

Notes:

  • For F4 (high-res) the sampled wave range is 3640 - 8980 Å (9110 Å),
        For F3 (med-res) the sampled wave range is 3640 - 8840 Å (8980 Å),
        For F1 (low-res) the sampled wave range is 3620 - 8580 Å (8700 Å),
        with the value in parentheses valid when extracting also the reddest order, even though it is partially clipped by the CCD.

  • The efficiencies are at the center of the blaze.

  • For the 200-micron low-res fiber the FWHM of the order profile in the spatial direction is about 7 pixels.
        For the 100-micron med-res and high-res fibers the FWHM of the order profile in the spatial direction is about 4 pixels.

  • The FWHM of the arc lines in the spectral direction is about 6 pix, 3 pix, and 2 pix for the low-, med-, and high-res fibers respectively.

  • Fringing is visible from 8000 Å and onward. At 9000 Å the peak-to-peak fringe amplitude is about 5%.


    ... with the old CCD13 and bundle B

    Based on observations of spectrophotometric standards in 2007, with the medium/low resolution fiber (R=45000/25000, aperture 1.3/2.5 arcsec) with good seeing, the efficiency of FIES (with fiber bundle B) is indicated in the table below.
    We note that the efficiency, and hence also the expected count rate, of the high-resolution fiber (R=65000, aperture 1.3 arcsec) is 0.6 times the indicated values in the table below.

    Wavelength
    (Å)
    Efficiency
    (Atm. + tel. + inst.)
    Dispersion
    (Å / pixel)
    3800 1.0 % 0.024
    3900 1.5 % 0.025
    4000 1.9 % 0.025
    4200 3.2 % 0.026
    4500 4.6 % 0.028
    5000 6.8 % 0.031
    6000 9.0 % 0.037
    7000 8.0 % 0.043

    Notes:

  • For the 200-micron low-res fiber the FWHM of the order profile in the spatial direction is 7.3 pixels.
        For the 100-micron med-res and high-res fibers the FWHM of the order profile in the spatial direction is 4.3 pixels.

  • The FWHM of the arc lines in the spectral direction is 6.3 pix, 3.4 pix, 2.3 pix for the low-, med-, and high-res fibers respectively.

  • Fringing is visible from 6300 Å and onward. At 7000 Å the peak-to-peak fringe amplitude is 10%. At 7300 Å the peak-to-peak fringe amplitude is 18%.

  • Back to top Last modified: 21-Oct-2016