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FP_SETUP

This ICL procedure prompts for all the parameters required for the data acquisition process.

If the detector is the CCD, the observer will be prompted for the following parameters:

• The dimensions of the CCD in x and y

• The binning factor

• The size of the CCD window in unbinned pixels

• The origin of the CCD window

• The exposure time for each plane of the datacube

• The name of the file specifying the order in which the planes of the etalon are to be observed. This file is simply a text file, containing the same number of records as there are planes in the datacube. Each record contains a single integer, defining one plane of the datacube. Whilst the etalon is being scanned, this file is used to determine which plane of the datacube should be observed next. For example, if record number 5 contained the integer 10, then the 5th image obtained would be of plane number 10. Use of this file allows the datacube to be scanned in a pseudo-random order, defined by the observer. It is up to the observer to make sure that each plane of the datacube is specified in the file once and only once.

• The number of etalon steps (i.e. the z dimension of the datacube) This must be less than 255.

• The start position for the etalon scan. The etalon gap is altered during an observation by applying an offset to the Z servo channel. The start position specified here is the Z offset to be used for the first plane of the datacube. It is not specified in physical units, but in 'microprocessor units'

• The size of the etalon step. This is the amount by which the Z offset (i.e. the etalon gap) is incremented between successive planes of the datacube. It is not specified in physical units, but in 'microprocessor units'

• The type of ramp function used. This should always be set to 0 for observations with the CCD.

• The frame number to be used for 2D images. During the night it will be necessary to take 2D calibration frames such as ring frames (see section 16.2). The parameter specified here determines the Z offset (i.e. etalon gap) to be used for 2D images. For example, if this parameter equals 10, then 2D images will be taken with the same etalon gap as plane number 10 in the datacubes.