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A simple combination of images without the absolute binding to the coordinates
07-09-2011, 04:27
Post: #1
A simple combination of images without the absolute binding to the coordinates
I have a 1500 images of the same sky region.
I have them all processed by SExtractor and got PSF* parameters.
After that, I sort it in ascending order by seeing parameter.
I want to combine the best images to obtain images with a high S / N.
The problem is that I have a very small field of view (10 arcsec) and very faint stars (There is not possible to find a reference catalog).
I want to use catalog produced by SExtractor for best image and make it the reference.
With SCAMP determine the displacement and rotation of the other images.
Then use SWarp combine them.
What is the easiest way to do this?
Given the fact that I know the scale of the pixel, that all images were obtained with the same CCD and telescope.
I found no example in the manual, although I'm sure many have faced with the task of combining images without the absolute binding of the coordinates. Simply combine the images by removing the offset and rotation relative to each other.

Thanks for helping.
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07-09-2011, 05:06
Post: #2
RE: A simple combination of images without the absolute binding to the coordinates
(07-09-2011 04:27)bmv Wrote:  I want to use catalog produced by SExtractor for best image and make it the reference. With SCAMP determine the displacement and rotation of the other images.

Attached is an IDL routine (which you're welcome to translate to whatever language you're using) that writes out a scamp-compatible reference catalog given ra, dec, magnitude, etc. (i.e., from your "best" SE catalog). (Note that I had to change the file to .txt to allow the forum to attach it! Change to .pro if downloading.) You can then use the ASTREF_CATALOG and ASTREFCAT_NAME optional scamp inputs to have scamp bypass cdsclient and use your home-grown catalog. Note that you may also have to increase ASTREF_WEIGHT to force each of your frames to align satisfactorily with your reference frame (based on the astrometric residuals), depending on how large the distortions are.

Good luck!

Cheers,
John


Attached File(s)
.txt  write_scamp_catalog.txt (Size: 4.55 KB / Downloads: 807)
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