The CONFIG File

A CONFIG is an ASCII file containing the settings of CGS4 and the data acquisition parameters. In order to set up the spectrometer the following parameters must be specified: the grating to be used, the central wavelength of the spectrum in microns, the order to use the grating in (unless echelle_auto_order was selected as grating), the CVF offset in microns, the slit width and its position angle and the sampling required for the observations. The data acquisition parameters to be specified in a CONFIG are: the data acquisition mode, the on-chip exposure time in seconds, the number of exposures to be co-added into an integration and the number of integrations per detector sampling position. A typical CONFIG, called TARGET, used to observe a target object is:

ASTRONOMICAL     configuration : TARGET
Basic (object) configuration:
ND_STARE             Acquisition configuration
   30.0000           exposure time
     1               exposures/integ
     1               scans
     4               sampling
2_pixels                sample range
    -90.00           position angle
N4                   filter
1_pixel              slit width
echelle_auto_order     grating
    1.2822           wavelength
 1                   order
    0.0000            cvf offset
off                  calibration lamp
   97                tungsten-halogen level
   10                lamp effective aperture
Flat configuration variant  (from object):
1x1                  Flat sampling
5.0                  calibration lamp
ND_STARE             Acquisition configuration
    1.0000           exposure time
    10               exposures/integ     
     3               integrations
Dark configuration variant (from object):
     1               exposures/integ
     1               integrations
Bias configuration variant (from dark):
     0.1200          exposure time
     50              exposures/integ
      3              integrations
Arc configuration variant (from object):
krypton              calibration lamp
N4                   filter
    1.2822           cvf wavelength
ND_STARE             Acquisition configuration
    0.5000           exposure time
    10               exposures/integ
     3               integrations

Setting up CGS4 for a Flat Field observation or for an Arc observation requires further parameters to be specified in the CONFIG file . These parameters are, for a Flat Field observation: the flat sampling , the flat lamp to be used, the flat acquisition mode, the integration exposure time in seconds, the number of exposures per integration and the number of integrations per observation; for an Arc observation: the required arc lamp, the echelle arc CVF wavelength (if the echelle is the grating to be used), the arc acquisition mode, the exposure time of one integration in seconds, the number of exposures per integration and finally the number of integrations per observation.