add further explanation in comment for re-inserting WCSAXES keyword

LSSTDESC · Jun 9, 2019 · ef7e897 · ef7e897
1 parent 699fc84
commit ef7e897
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/python/desc/imsim/camera_readout.py b/python/desc/imsim/camera_readout.py
@@ -461,9 +461,10 @@ def write_fits_file(self, outfile, overwrite=True, run_number=None,
         """
         output = fits.HDUList(fits.PrimaryHDU())
         output[0].header = self.eimage[0].header
-        # Re-insert the WCSAXES keyword to precede any other WCS
-        # keywords as stipulated in the FITS Standard, version 4.0,
-        # section 8.2.
+        # Since `.header` acts like an unordered dict when set like
+        # this, we need to re-insert the WCSAXES keyword to precede
+        # any other WCS keywords as stipulated in the FITS Standard,
+        # version 4.0, section 8.2.
         wcsaxes = output[0].header['WCSAXES']
         del output[0].header['WCSAXES']
         output[0].header.insert(5, ('WCSAXES', wcsaxes, ''))