Reproject to Non-standard Coordinate Systems

[zheshishuoshuo]

Hello, I would like to use reproject_interp to reproject a FITS image in the Galactic coordinate system to a non-standard FITS coordinate system (such as the Magellanic coordinates or the Sagittarius stream coordinates). How can I achieve this?

[Cadair]

hello @zheshishuoshuo

reproject itself has no built-in awareness of coordinate systems, it relies on the input and output WCSes (conforming to the APE 14 WCS API: https://docs.astropy.org/en/latest/wcs/wcsapi.html) to do the coordinate conversions. This means if you want to reproject to a custom coordinate system (i.e. not one supported by astropy.wcs) you have two main options: 1) Make a gwcs object to represent your WCS or 2) make a completely custom LowLevelWCS object where you implement pixel_to_world_values and world_to_pixel_values and the other required properties.

Hope that helps!