Source code for iris_pipeline.background.background_step

#! /usr/bin/env python

from jwst.stpipe import Step
from jwst import datamodels
from . import background_sub


__all__ = ["BackgroundStep"]


class BackgroundStep(Step):
    """
    BackgroundStep:  Subtract background exposures from target exposures.
    """

    spec = """
        sigma = float(default=3.0)  # Clipping threshold
        maxiters = integer(default=None)  # Number of clipping iterations
    """

    def process(self, input, bkg_list):

        """
        Subtract the background signal from target exposures by subtracting
        designated background images from them.

        Parameters
        ----------
        input: JWST data model
            input target data model to which background subtraction is applied

        bkg_list: filename list
            list of background exposure file names

        Returns
        -------
        result: JWST data model
            the background-subtracted target data model
        """

        # Load the input data model
        with datamodels.open(input) as input_model:

            if input_model.meta.exposure.type in ["NIS_WFSS", "NRC_WFSS"]:

                # Get the reference file names
                bkg_name = self.get_reference_file(input_model, "wfssbkg")
                wlrange_name = self.get_reference_file(input_model, "wavelengthrange")
                self.log.info("Using WFSSBKG reference file %s", bkg_name)
                self.log.info("Using WavelengthRange reference file %s", wlrange_name)

                # Do the background subtraction for WFSS/GRISM data
                result = background_sub.subtract_wfss_bkg(
                    input_model, bkg_name, wlrange_name
                )
                result.meta.cal_step.back_sub = "COMPLETE"

            else:
                # Do the background subtraction
                result = background_sub.background_sub(
                    input_model, bkg_list, self.sigma, self.maxiters
                )
                result.meta.cal_step.back_sub = "COMPLETE"

        return result