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ccdstack - stack images, with simple gridding option if WCS differs
ccdstat stacks images and
takes their mean, allowing for the WCS to be different. The current re-sampling
method is simple: the first image inherits the WCS for the output stacked
image, all other images compute in which pixel of the first image this
pixel would contribute. No other gridding or convolution is done yet (but
The following parameters are recognized in
any order if the keyword is also given:
the first image determines the WCS of the output image, it can be also
be used as a template by setting its image values to 0. ccdgen(1NEMO)
be used for this.
- Input image files, first image
sets the WCS.
- Output image file. No default.
- Scalar weight per
image [1 for all].
- Are the weights still SIGMA (t), or straight
- Bad value to ignore 
- Use the WCS to re-sample for stacking with
the WCS of the first image. If not set, images are stacked "as is". If WCS
is set, you can thus stack images of unequal size. Pixels falling outside
that of the first image are simply ignored. [Default: t]
- If given,
these are the convolution FWHM kernels in each dimension of the input images.
It only makes sense to use this is wcs=t is used. Not Implemented Yet.
- Conserve flux (1)
or not (0) in each dimension. Not implemented yet.
Here is a contrived example of mosaicing two fields in
a Plummer sphere projection. It will generate a template with all 0 values
(which don’t contribute to the stack), and adding in the two fields:
mkplummer p1 100000
snapgrid p1 ccd1 xrange=0:1 yrange=0:1 nx=16 ny=16
snapgrid p1 ccd2 xrange=-1:0 yrange=-1:0 nx=16 ny=16
ccdgen "" ccd3 spar=0 size=64,64 cdelt=4/64,4/64
ccdstack ccd3,ccd1,ccd2 ccd12
ccdstack ccd3,ccd2,ccd1 ccd21
21-May-21 V0.1 Drafted PJT
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