UseCase: SetImageWCS


Astronomer, Data Flow Scientist


Association of correct WCS to an image file


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Image file (in FITS format?) with indication of pointing centre and pixel size.


  1. Display the image from a local disk or via a server. It either has a rough WCS or the rough centre, orientation and scale is known or they can be attached from another file.
  2. Overlay a remote astrometric catalogue e.g. GSC at ESO as Skycat/GAIA.
  3. Mark the stars on the image and drag/assign the catalogue stars or run a detection program on-the-fly which has some background following and other detection parameters like thresholding parameters, image saturation levels.
  4. Perform a fit where the residuals might be shown as vectors on the original plot.
  5. Edit the fitted stars by hand or the program sigma clips iteratively.
  6. Accept the fit.
  7. Save the image with the new WCS on a local disk or back on the server.


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GoodStyle: Please add comments below. This area should be used for refinement of the above document. If you want to ask questions or start a dialogue with the author, please use (or create) a topic in the Use Cases Forum.
Author: Once the refinements here and comments in the forum die down, perhaps you could rewrite the problem, incorporating the comments and refinements.

-- NicholasWalton - 27 Jan 2002

Topic revision: r2 - 2002-02-08 - 09:17:28 - TonyLinde
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