Update docs

Author: melanieclarke

docs/jwst/clean_flicker_noise/arguments.rst

@@ -31,6 +31,15 @@ the behavior of the processing.
   affected by failed-open MSA shutters.  For MIRI imaging, mask
   regions of the detector not used for science.
 
+``--apply_flat_field`` (boolean, default=False)
+  If set, images are flat-corrected prior to fitting background
+  and noise levels.  A full-frame flat field image
+  (reference type FLAT) is required. For modes that do not provide
+  FLAT files via CRDS, including all NIRSpec modes, a manually
+  generated override flat is required to enable this option.
+  Use the `override_flat` parameter to provide an alternate flat image
+  as needed.
+
 ``--n_sigma`` (float, default=2.0)
   The sigma-clipping threshold to use when searching for outliers
   and illuminated pixels to be excluded from use in the background

docs/jwst/clean_flicker_noise/main.rst

@@ -184,6 +184,9 @@ information on all referenced parameters.
       This will mask out regions of the detector under the metering
       structure.
 
+   #. If `apply_flat_field` is set and a flat file is available, divide the
+      draft rate data by the flat image.
+
    #. Iteratively sigma clip the data to get a center value (mean or median)
       and sigma value (standard deviation).
 
@@ -200,6 +203,9 @@ information on all referenced parameters.
 
    #. Make a diff image (current group – previous group) to correct.
 
+   #. If `apply_flat_field` is set and a flat file is available, divide the
+      diff image by the flat image.
+
    #. Fit and remove a background level, using the scene mask to identify
       background pixels.
 
@@ -231,7 +237,8 @@ information on all referenced parameters.
          detector channel.
 
    #. Restore the background level to the cleaned, background-subtracted
-      diff image.
+      diff image.  Also restore the flat structure if needed by multiplying the
+      cleaned diff by the flat image.
 
    #. Add the cleaned diff back to a cleaned version of the previous
       group image.

jwst/clean_flicker_noise/clean_flicker_noise_step.py

@@ -83,7 +83,7 @@ def process(self, input):
             (reference type FLAT) is required. For modes that do not provide
             FLAT files via CRDS, including all NIRSpec modes, a manually
             generated override flat is required to enable this option.
-            Use the `override_flat` parameter to provide alternate flat images
+            Use the `override_flat` parameter to provide an alternate flat image
             as needed.
 
         n_sigma : float, optional