| # Download an example FITS file, create a 2D cutout, and save it to a | |
| # new FITS file, including the updated cutout WCS. | |
| from astropy.io import fits | |
| from astropy.nddata import Cutout2D | |
| from astropy.utils.data import download_file | |
| from astropy.wcs import WCS | |
| def download_image_save_cutout(url, position, size): | |
| # Download the image | |
| filename = download_file(url) | |
| # Load the image and the WCS | |
| hdu = fits.open(filename)[0] | |
| wcs = WCS(hdu.header) | |
| # Make the cutout, including the WCS | |
| cutout = Cutout2D(hdu.data, position=position, size=size, wcs=wcs) | |
| # Put the cutout image in the FITS HDU | |
| hdu.data = cutout.data | |
| # Update the FITS header with the cutout WCS | |
| hdu.header.update(cutout.wcs.to_header()) | |
| # Write the cutout to a new FITS file | |
| cutout_filename = 'example_cutout.fits' | |
| hdu.writeto(cutout_filename, overwrite=True) | |
| if __name__ == '__main__': | |
| url = 'https://astropy.stsci.edu/data/photometry/spitzer_example_image.fits' | |
| position = (500, 300) | |
| size = (400, 400) | |
| download_image_save_cutout(url, position, size) | |