1. The first thing to do is to remove all the covers from lenses, all mirrors, the grating, and grisms in the coude room.
  2. Then switch on the electronic boxes for the flat-field and ThAr lamps, for the slit-view camera, and for turntable of the grating.
  3. You may change the slit width by turning the hand-wheel. A slit width of 0.52mm (corresponding to 1.2") will give you a two pixel resolution of about 67000. Make sure that the slit height is set to 3mm.
  4. The spectrograph is operated from the workstation ''sonne'' in the control room. After login, just type ''start_echelle'' on the workstation. A small window will appear (Fig. 4).

    Echelle Control Window

    Fig 4: Echelle control window.

  5. In the next step, the spectrograph will initialise itself by putting the grism-wheel to the ''white'' position (no cross dispersion). The program will then ask for the grating angle. 67.5 degrees is the default for the Echelle grating. If the grating ends up at an angle of 67.4999 press 67.5 again, to bring the grating to the correct position. The movement of the grating is indicated by the ''turning wheel''.
  6. After the spectrograph is initialised, you can then choose the grism (UV, VIS, IR) to select the desired wavelength region. The movement of the grism-slide is indicated by the green flashing lights. When the correct position is reached, a green light comes up.

    Taking flats, arcs and stellar spectra

    For taking flats or arcs, just press the corresponding button (Flat Field or ThAr) in the middle panel of Echelle control window. After pressing the button, a small mirror will be moved in and the lamp will be switched on. Do not forget to switch off the Fernsehleiteinrichtung when moving the telescope, or taking flats and arcs.

    The grisms can be changed at any time by pressing the corresponding button.

    Focusing of the telescope can be done from the ''white box'' in the control room, or from the handset in the slit-room.

    CCD control

    The CCD camera is now operated from the ''sonne'' as well. The CCD program is the same as in the Schmidt mode. For more details have a look at the manual for the CCD-camera system

    Iodine cell

  7. The temperature of the cell is regulated by the small black electronic box in the slit-room. A temperature of 70 C is recommended for the observations but temperatures in the range between 60 C and 80 C can also be used.
  8. The cell needs some time to reach a temperature of 70 C. It is thus recommended to switch it on two hours prior to the observations. When using the cell, stability of the spectrograph is an issue. We thus suggest to startup the whole system two hours before starting with the observations.
  9. Because the iodine lines are only between 5000 to 6300 Å, select the VIS grism.
  10. The cell can be moved in and out of the beam with the little knob on the left side of the blue slit-control unit (below the ThAr lamp).


  11. Exit the TV guiding and acquisition system
  12. Exit the Echelle control window.
  13. Switch of electronic boxes in the slit room, and put pack all covers on to mirrors, the grating, the lenses, and the grisms.
  14. Switch the CCD camera to wipe