Hard-and-fast rule for selecting the proper value of sigclip. The background a pixel needs to be to consider it a cosmic ray. The key parametersĪre readnoise, the read noise, and sigclip, which determines how far above The actual invocation of LACosmic is fairly convenient. append ( fileobj ) FileNotFoundError: No such file or directory: 'example2-reduced/mask_from_dark_current.fits' FileIO ( name_or_obj, 'r' ) 272 if is_url and not cache : 273 delete_fds. gen ) 114 except StopIteration : 115 raise RuntimeError ( 'generator didn't yield' ) from None File /usr/share/miniconda/envs/test/lib/python3.8/site-packages/astropy/utils/data.py:271, in get_readable_fileobj (name_or_obj, encoding, cache, show_progress, remote_timeout, sources, http_headers) 266 if is_url : 267 name_or_obj = download_file ( 268 name_or_obj, cache = cache, show_progress = show_progress, 269 timeout = remote_timeout, sources = sources, 270 http_headers = http_headers ) -> 271 fileobj = io. func 112 try : -> 113 return next ( self. _enter_ () 198 except OSError : 199 raise File /usr/share/miniconda/envs/test/lib/python3.8/contextlib.py:113, in _GeneratorContextManager._enter_ (self) 111 del self. _cls, * args, ** kwargs ) File /usr/share/miniconda/envs/test/lib/python3.8/site-packages/astropy/io/registry/core.py:197, in UnifiedInputRegistry.read (self, cls, format, cache, *args, **kwargs) 195 try : 196 ctx = get_readable_fileobj ( args, encoding = 'binary', cache = cache ) -> 197 fileobj = ctx. dimensionless_unscaled ) File /usr/share/miniconda/envs/test/lib/python3.8/site-packages/astropy/nddata/mixins/ndio.py:59, in NDDataRead._call_ (self, *args, **kwargs) 58 def _call_ ( self, * args, ** kwargs ): -> 59 return self. read ( ex2_path / 'mask_from_dark_current.fits', unit = u. Input In, in () -> 1 dark_mask = CCDData.

FileNotFoundError Traceback (most recent call last) They can be removed by properly combining the images. Work well for removing them from calibration images and is unnecessary because The method described below for removing cosmic rays from science images will not A detailedĭescription of each option is discussed in the section on image combination. AnĪlternative would be to combine the images using a median. Sigma clipping (to exclude extreme pixels in individual images like the one withĪ cosmic ray) will eliminate the cosmic ray from the combined dark image. Will almost certainly not be affected by a cosmic ray in any of the other darkĬombining those images by averaging (to reduce noise as much as possible) and A pixel affected by a cosmic ray in one of the dark images, for example, Random events that will affect different parts of each of the calibration The most convenient way to remove cosmic rays from calibration images (bias, dark, andįlat images) is to combine them properly.

Cosmic rays