Blank images based on primary beam

fits_helpers/wsclean_blank_image_beyond_primary_beam.py

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+#!/usr/bin/env python
+import argparse
+import os
+
+from astropy.io import fits # type: ignore
+import numpy as np
+
+def blank_image(imname: str, beamlvl: float, MFS: bool) -> str:
+    """ Blanks images created by WSClean beyond a specified level of the primary beam.
+
+    Args:
+        imname : str
+            Name of the images to blank as passed to WSClean's -name option.
+        beamlvl : float
+            Level of the primary beam to blank below.
+        MFS : bool
+            Set to True if the image was made in MFS mode (i.e. channels-out > 1).
+
+    Returns:
+        imname_blanked : str
+            Base name of the blanked images.
+    """
+    if MFS:
+        im_app = imname + '-MFS-image.fits'
+        im_pb = imname + '-MFS-image-pb.fits'
+        im_beam = imname + '-MFS-beam-0.fits'
+    else:
+        im_app = imname + '-image.fits'
+        im_pb = imname + '-image-pb.fits'
+        im_beam = imname + '-beam-0.fits'
+
+    if not os.path.isfile(im_app):
+        raise FileNotFoundError(f"Image {im_app} does not exist.")
+    if not os.path.isfile(im_pb):
+        raise FileNotFoundError(f"Image {im_pb} does not exist.")
+    if not os.path.isfile(im_beam):
+        raise FileNotFoundError(f"Image {im_beam} does not exist.")
+    beam = fits.getdata(im_beam)
+    mask = beam > beamlvl
+
+    data_app = fits.getdata(im_app)
+    data_pb = fits.getdata(im_pb)
+
+    im_app_masked = np.where(mask, data_app, np.nan)
+    im_pb_masked = np.where(mask, data_pb, np.nan)
+
+    print(f'Writing primary-beam-blanked images for {imname}...')
+    fits.writeto(f"{imname}.pbblanked-MFS-image.fits", data=im_app_masked, header=fits.getheader(im_app))
+    fits.writeto(f"{imname}.pbblanked-MFS-image-pb.fits", data=im_pb_masked, header=fits.getheader(im_pb))
+    print('Done')
+    return imname + ".pbblanked"
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser("Blank a WSClean image to a certain value of the primary beam.")
+    parser.add_argument("--imagename", type=str, help="Image name as passed to WSClean.")
+    parser.add_argument("--beam_cut", type=float, help="Fractional value of the primary beam to blank to relative to the centre of the image.")
+    parser.add_argument("--no-MFS", action="store_true", required=False, help="Set if image was made using a single output channel (i.e. -channels-out=1 or not given).")
+    args = parser.parse_args()
+
+    blank_image(args.imagename, args.beam_cut, not args.no_MFS)