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Prepare the create_mask process by fitting some optical parameters and analysing the cross-dispersion profile on an arc exposure with the help of an ad-hoc table giving the positions of a given line on the CCD.

-arc none Input arc frame
-nbin 100 Number of bins in histograms (UNUSED)
-threshold 0.95 Frac of pixel population considered as mpups (UNUSED)
-fracdist 0.1 1/2-size of the analysis area around mpup
-analysis NULL Output analysis table
-mask mask Output mask
-nggeo 3 Gaussian components in the geometric PSF (3|5|7)
-ngpsf 3 Gaussian components in the global PSF (>0)
-ngloc 1 Gaussian components in the local PSF (<=1)
  • If <0, global PSF is discarded, and Core PSF = Geometric PSF
  • If >0, Core PSF = Geometric PSF $\otimes$ Global PSF
-lambda none Reference wavelength of the input micropupils
-table NULL Input 1st-order mpup-position table
-offset NULL Manual offset to input coordinates
Error status
Input table
Describe the use and the input columns (from ad-hoc analysis): :X1,:Y1 (FLOAT) The input columns were previously :XCEN,:YCEN (DOUBLE) from Midas.
The simple $r^2$-distortion model used here do not fit properly the pseudo mpup position (structured discrepancy up to 4.5 px). Therefore, one cannot compute the "real undistorted" position, needed to compute the sky coordinates.

Test the existence and use the variance extension in the preproc images.

Generated on Thu Oct 27 00:00:24 2005 for Snifs by doxygen 1.3.5