Single Order Spectrograph


Spectrum of the star (gamma UMa) on CCD. On the central right there is Halpha, far left one can see telluric lines.


Cross section of the star (gamma UMa) on CCD.


Final reduced spectrum of gamma UMa.


Thorium Argon comparison lamp.


Cross section of the spectrum on CCD. Flat field.


Basic characteristics of the CCD chip

  • Pylon 2KB_eXcelon
  • Scientic grade: 1
  • Back illuminated
  • Detector ID: PyLoN 2048x512BX
  • Chip ID: E2V 42-10 BX
  • 2048x512 pixels, 13.5 micrometers per one pixel.
  • Cooling: liquid nitrogen
  • Temperature: -115 degrees C
  • Reading out frequency: 50kHz
  • Gain: high
  • Limited etaloning - lowered oscillations (unwanted fringes).
  • Dispersion axis: 1 (along lines)
  • Input window is on the bottom of the dewar. Double-sided MgF2 coating
  • vacuum window, optimised at 250nm.

    • Quantum efficiency of the CCD chip. Red line is our 2KB_eXcelon.


    Transmission of the input window. We have MgF2 double-side coating window (violet line).


    Comparison of etaloning (fringing) of B-excelon and B chip technology. We are equipped with lowered fringing chip (grey-green line).

    The ranges of exposed spectra

    At first, we present tables and graphs depicting the beginnings and ends of exposed spectra as they depend on grating angle. Thus one can fit and find another angle of grating to depict asked spectral regions.

    For the first spectral order (red regions)

    Grating angle Spectral order
    Increments Degrees Beginning End
    532135.788401.48869.9
    543035.258197.28666.3
    638230.626406.26878.6
    645730.256263.56736.0
    694327.885328.65801.4




    and for the second spectral order (blue regions)

    Grating angle Spectral order
    Increments Degrees Beginning End
    471238.754758.84991.1
    504037.154459.94693.4
    524236.174273.74507.7



    One can see that grating angles in increments are in "anticorrelation" with the degrees (when increments are increasing, degrees are decreasing).

    Examples of ThAr spectra exposed in Ondrejov, identification

    See also KPNO ThAr atlas

    First spectral order - red regions

    Gaia region



    O I region



    He I region



    H alpha region



    N II region



    Second spectral order - blue regions

    H beta region



    H gamma region



    Fe II region



    Mg II region



    Region of high Balmer lines



    We do not recommend to observe under 3800A (i.e. under the last presented region) because the efficiency of the CCD chip is falling down steeply around these wavelengths.