Pixflat

[julienguy]

New script to compute a pixel flat field from a flat exposure obtained during the CCD qualification tests instead of the flat field slit in a spectrograph. This code is written to compute a temporary flat for the new SM5 RED CCD (M1-28).

Usage:

desi_compute_broadband_pixel_flatfield [-h] -i INFILE -o OUTFILE -c CAMERA [--sigma SIGMA]

Computes a pixel level flat field image from a flat image obtained during the CCD qualification tests, like
/global/cfs/cdirs/desi/spectro/teststand/rawdata/v0/M1-28_report/Flats/flat_median_700.fits. This code is designed for LBL CCDs in the RED cameras for now.

optional arguments:
  -h, --help            show this help message and exit
  -i INFILE, --infile INFILE
                        path to input flat image fits file (default: None)
  -o OUTFILE, --outfile OUTFILE
                        output flatfield image filename (default: None)
  -c CAMERA, --camera CAMERA
                        camera: only RED implemented for now (default: None)
  --sigma SIGMA         sigma of 2D Gaussian convolution in pixels (default: 20.0)

Method: after remapping the CCD quadrants, divide the image in each quadrant by a median per row, a median per column, and a Gaussian convolved version of the same image.

Example (for SM2 where we also have the pixflat from the flatfield slit):

desi_compute_broadband_pixel_flatfield -i /global/cfs/cdirs/desi/spectro/teststand/rawdata/v0/M1-46_report/Flats/flat_median_700.fits -o flat-sm2-r-labtest.fits -c red
ds9 $DESI_SPECTRO_CALIB/ccd/pixflat-sm2-r.fits flat-sm2-r-labtest.fits

(left from flatfield slit , right from M1-46_report/Flats/flat_median_700.fits)

[sbailey]

Looks good, thanks. Go ahead and merge when tests pass.