The skymatch_step function (class name SkyMatchStep) is the top-level function used to call the skymatch operation from the JWST calibration pipeline.

JWST pipeline step for sky matching.


Mihai Cara

class jwst.skymatch.skymatch_step.SkyMatchStep(name=None, parent=None, config_file=None, _validate_kwds=True, **kws)[source]

SkyMatchStep: Subtraction or equalization of sky background in science images.

Create a Step instance.

  • name (str, optional) – The name of the Step instance. Used in logging messages and in cache filenames. If not provided, one will be generated based on the class name.

  • parent (Step instance, optional) – The parent step of this step. Used to determine a fully-qualified name for this step, and to determine the mode in which to run this step.

  • config_file (str path, optional) – The path to the config file that this step was initialized with. Use to determine relative path names of other config files.

  • **kws (dict) – Additional parameters to set. These will be set as member variables on the new Step instance.

class_alias = 'skymatch'

This is where real work happens. Every Step subclass has to override this method. The default behaviour is to raise a NotImplementedError exception.

reference_file_types = []
spec = '\n        # General sky matching parameters:\n        skymethod = option(\'local\', \'global\', \'match\', \'global+match\', default=\'match\') # sky computation method\n        match_down = boolean(default=True) # adjust sky to lowest measured value?\n        subtract = boolean(default=False) # subtract computed sky from image data?\n\n        # Image\'s bounding polygon parameters:\n        stepsize = integer(default=None) # Max vertex separation\n\n        # Sky statistics parameters:\n        skystat = option(\'median\', \'midpt\', \'mean\', \'mode\', default=\'mode\') # sky statistics\n        dqbits = string(default=\'~DO_NOT_USE+NON_SCIENCE\') # "good" DQ bits\n        lower = float(default=None) # Lower limit of "good" pixel values\n        upper = float(default=None) # Upper limit of "good" pixel values\n        nclip = integer(min=0, default=5) # number of sky clipping iterations\n        lsigma = float(min=0.0, default=4.0) # Lower clipping limit, in sigma\n        usigma = float(min=0.0, default=4.0) # Upper clipping limit, in sigma\n        binwidth = float(min=0.0, default=0.1) # Bin width for \'mode\' and \'midpt\' `skystat`, in sigma\n    '