[AstroPy] WCS reprojection

[Leo Singer]

> On Jun 11, 2014, at 11:10, Stuart Mumford <stuart at mumford.me.uk> wrote:
> 
> Hello,
> 
> I am looking for a way to change the projection of my solar image data. Specifically to re-project my TAN projected helioprojective Cartesian data array into a CAR Plate carree projected heliographic map.
> 
> The only thing that I could find that looks like it might be able to do this is Kapteyn's coord_map function (https://www.astro.rug.nl/software/kapteyn/wcs.html#function-coordmap). Are there other options? Is this possible using astropy.wcs?
> 
> Any suggestions are welcome.
> 
> Thanks
> Stuart

Hi Stuart,

If you were to do this in Astropy, the basic algorithm for nearest-neighbor mapping between the two projections would be:

Construct new WCS object representing target projection
Create array of pixels in target projection
For each pixel, convert to world coordinates with WCS.wcs_pix2world
Convert to pixel index in original projection with WCS.wcs_world2pix
Retrieve value from original array, store in target array

Leo
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