WavecorrStep

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

Bases: JwstStep

Apply wavelength offsets to off-center NIRSpec sources.

Wavelength corrections are applied only to point sources in NIRSpec MOS and FS data.

The algorithm uses a reference file which is a look-up table of wavelength_correction as a function of slit_x_position and wavelength. The x direction is the one parallel to dispersion/wavelength for both MOS and FS slits.

The slit_x_position is read from the source_xpos attribute in the input slit metadata. For MOS data, the x position is read from the msa_metadata_file in the assign_wcs step. For FS data, the x position is calculated from the dither x_offset value in the extract_2d step.

The wavelength value used to look up the wavelength correction at each dispersion element is an average of the wavelength values in the cross-dispersion direction at that element.

Create a Step instance.

Parameters:

  • 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 or pathlib.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

class_alias

reference_file_types

spec

Methods Summary

process(step_input)

Apply the wavelength correction to the input data.

Attributes Documentation

class_alias = 'wavecorr'
reference_file_types: ClassVar = ['wavecorr']
spec

Methods Documentation

process(step_input)[source]

Apply the wavelength correction to the input data.

Parameters:

step_input (DataModel or str) – Input data to correct.

Returns:

The corrected data.

Return type:

DataModel