Divide the combined Sflat by the combined Dflat using 'mscarith'.
Ideally the image will be uniform, accept for the ghost pupil in KPNO data.
If not uniform, must decide which is better. This can be done by ccdproc-ing
(with the flatc-) a sample of narrowband data and by hand, dividing images
by the cooresponding combined Sflat and Dflat. 'Mscexam' can be used to
determine the "flatter" image.
PACKAGE = mscred
TASK = flatcombine
input = @dB List of flat field images to combine
(output = master) Output flat field root name
(combine= average) Type of combine operation
(reject = crreject) Type of rejection
(ccdtype= dome flat) CCD image type to combine
(process= yes) Process images before combining?
(subsets= yes) Combine images by subset parameter?
(delete = no) Delete input images after combining?
(scale = mode) Image scaling
(statsec= ) Image section for computing statistics
(nlow = 1) minmax: Number of low pixels to reject
(nhigh = 1) minmax: Number of high pixels to reject
(nkeep = 1) Minimum to keep (pos) or maximum to reject (neg)
(mclip = yes) Use median in sigma clipping algorithms?
(lsigma = 3.) Lower sigma clipping factor
(hsigma = 3.) Upper sigma clipping factor
(rdnoise= 20) ccdclip: CCD readout noise (electrons)
(gain = 2.8) ccdclip: CCD gain (electrons/DN)
(snoise = 0.) ccdclip: Sensitivity noise (fraction)
(pclip = -0.5) pclip: Percentile clipping parameter
(blank = 1.) Value if there are no pixels
(mode = ql)