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Aligning the CCD Camera for Rotation

In order to ease extraction of the individual spectral orders the CCD camera should be aligned so that the central order runs vertically along the CCD. Note that due to curvature of the echellogram (see Fig. 6) it will not be possible to have all the individual orders running vertically. The CCD camera can be rotated; the securing Allen bolts have to be loosened, and the CCD dewar rotated. The rotation position is measured with micrometer D. A change in micrometer reading of +1mm gives a rotation of approximately ?? pixels end to end on the TEK chip.

Before and after each adjustment to the dewar take a short glance exposure with the echelle configured to the wavelength to be used, a tungsten lamp and slit length set to automatic. The commands for this would be:

Each glance run can be transferred to the SparcStation where the iraf IMEXAMINE routine can be used to measure the position of the echelle order at the top and bottom of the CCD image.

It may be neccassary to make more than one adjustment to the CCD dewar rotational postion before the echelle orders are satisfactorily aligned on the detector.