class jwst.tweakreg.TweakRegStep(name=None, parent=None, config_file=None, _validate_kwds=True, **kws)[source]

Bases: jwst.stpipe.Step

TweakRegStep: Image alignment based on catalogs of sources detected in input 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.

Attributes Summary



Methods Summary


This is where real work happens.

Attributes Documentation

reference_file_types = []
spec = "\n save_catalogs = boolean(default=False) # Write out catalogs?\n catalog_format = string(default='ecsv') # Catalog output file format\n kernel_fwhm = float(default=2.5) # Gaussian kernel FWHM in pixels\n snr_threshold = float(default=10.0) # SNR threshold above the bkg\n brightest = integer(default=1000) # Keep top ``brightest`` objects\n peakmax = float(default=None) # Filter out objects with pixel values >= ``peakmax``\n enforce_user_order = boolean(default=False) # Align images in user specified order?\n expand_refcat = boolean(default=False) # Expand reference catalog with new sources?\n minobj = integer(default=15) # Minimum number of objects acceptable for matching\n searchrad = float(default=1.0) # The search radius in arcsec for a match\n use2dhist = boolean(default=True) # Use 2d histogram to find initial offset?\n separation = float(default=0.5) # Minimum object separation in arcsec\n tolerance = float(default=1.0) # Matching tolerance for xyxymatch in arcsec\n xoffset = float(default=0.0), # Initial guess for X offset in arcsec\n yoffset = float(default=0.0) # Initial guess for Y offset in arcsec\n fitgeometry = option('shift', 'rscale', 'general', default='general') # Fitting geometry\n nclip = integer(min=0, default=3) # Number of clipping iterations in fit\n sigma = float(min=0.0, default=3.0) # Clipping limit in sigma units\n align_to_gaia = boolean(default=False) # Align to GAIA catalog\n gaia_catalog = option('GAIADR2', 'GAIADR1', default='GAIADR2')\n min_gaia = integer(min=0, default=5) # Min number of GAIA sources needed\n save_gaia_catalog = boolean(default=False) # Write out GAIA catalog as a separate product\n "

Methods Documentation


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