.. _calwebb_coron3:

calwebb_coron3: Stage 3 Coronagraphic Processing
================================================

:Class: `jwst.pipeline.Coron3Pipeline`
:Alias: calwebb_coron3

The stage 3 coronagraphic pipeline is to be applied to
associations of calibrated NIRCam coronagraphic and MIRI Lyot and 4QPM
exposures, and is used to produce PSF-subtracted, resampled, combined images
of the source object.

The steps applied by the ``calwebb_coron3`` pipeline are shown in the table
below.

+---------------------------------------------------+
| calwebb_coron3                                    |
+===================================================+
| :ref:`outlier_detection <outlier_detection_step>` |
+---------------------------------------------------+
| :ref:`stack_refs <stack_refs_step>`               |
+---------------------------------------------------+
| :ref:`align_refs <align_refs_step>`               |
+---------------------------------------------------+
| :ref:`klip <klip_step>`                           |
+---------------------------------------------------+
| :ref:`resample <resample_step>`                   |
+---------------------------------------------------+

The high-level processing provided by these steps is:

1) CR-flag all PSF and science target exposures
2) Accumulate all reference PSF images into a single product
3) Align every PSF image to every science target image
4) Compute an optimal PSF fit and subtract it from every science target image
5) Combine the PSF-subtracted and CR-flagged images into a single resampled image

Currently the individual steps shown above can only be run in a convenient way by
running the ``calwebb_coron3`` pipeline on an association (ASN) file that lists the
various science target and reference PSF exposures to be processed.

Arguments
---------
The ``calwebb_coron3`` pipeline does not have any optional arguments.

Inputs
------

3D calibrated images
^^^^^^^^^^^^^^^^^^^^

:Data model: `~jwst.datamodels.CubeModel`
:File suffix: _calints

The input to ``calwebb_coron3`` must be in the form of an ASN file that lists
one or more exposures of a science target and one or more  reference PSF targets.
The individual target and reference PSF exposures should be in the form of 3D
calibrated ("_calints") products from :ref:`calwebb_image2 <calwebb_image2>`
processing. Each pipeline step will loop over the 3D stack of per-integration images
contained in each exposure.

An example ASN file containing 2 science target and 1 reference PSF target exposures is
shown below. Only 1 product is defined, corresponding to the science target, with members
consisting of exposures of both the science target and the reference PSF target, as
indicated by the "exptype" values for each::

 {"asn_type": "coron3",
  "asn_rule": "candidate_Asn_Coron",
  "program": "10005",
  "asn_id": "c1001",
  "target": "t001",
  "asn_pool": "jw10005_20181020T033546_pool",
  "products": [
      {"name": "jw10005-c1001_t001_nircam_f430m-maskrnd-sub320a430r",
       "members": [
           {"expname": "jw10005009001_02102_00001_nrcalong_calints.fits",
            "exptype": "psf"
           },
           {"expname": "jw10005006001_02102_00001_nrcalong_calints.fits",
            "exptype": "science"
           },
           {"expname": "jw10005003001_02102_00001_nrcalong_calints.fits",
            "exptype": "science"
           }
       ]
      }
  ]
 }

Outputs
-------

CR-flagged images
^^^^^^^^^^^^^^^^^

:Data model: `~jwst.datamodels.CubeModel`
:File suffix: _crfints

If the :ref:`outlier_detection <outlier_detection_step>` step is applied, a new version of
each exposure is created, in which the DQ array is updated to flag pixels detected
as outliers. These files use the "_crfints" (CR-Flagged per integration)
product type suffix and include the association candidate ID, e.g.
"jw8607342001_02102_00001_nrcb3_a3001_crfints.fits."

3D stacked PSF images
^^^^^^^^^^^^^^^^^^^^^

:Data model: `~jwst.datamodels.CubeModel`
:File suffix: _psfstack

The data from each input PSF reference exposure are concatenated into a single
combined 3D stack by the :ref:`stack_refs <stack_refs_step>` step, for use by subsequent
steps. The stacked PSF data get written to disk in the form of a "_psfstack" product.
The output file name is source-based, using the product name specified in the
ASN file, e.g. "jw86073-a3001_t001_nircam_f140m-maskbar_psfstack.fits."

4D aligned PSF images
^^^^^^^^^^^^^^^^^^^^^

:Data model: `~jwst.datamodels.QuadModel`
:File suffix: _psfalign

For each science target exposure, all of the reference PSF images in the
"_psfstack" product are aligned to each science target integration and saved to
a 4D "_psfalign" product by the :ref:`align_refs <align_refs_step>` step. The output file
name is exposure-based, with the addition of the associated candidate ID, e.g.
"jw8607342001_02102_00001_nrcb3_a3001_psfalign.fits."

3D PSF-subtracted images
^^^^^^^^^^^^^^^^^^^^^^^^

:Data model: `~jwst.datamodels.CubeModel`
:File suffix: _psfsub

For each science target exposure, the :ref:`klip <klip_step>` step applies PSF fitting and
subtraction for each integration, resulting in a 3D stack of PSF-subtracted
images. The data for each science target exposure are saved to a "_psfsub"
product, using exposure-based file names, e.g.
"jw8607342001_02102_00001_nrcb3_a3001_psfsub.fits."

2D resampled image
^^^^^^^^^^^^^^^^^^

:Data model: `~jwst.datamodels.ImageModel`
:File suffix: _i2d

The :ref:`resample <resample_step>` step is applied to the CR-flagged products to create a
single resampled and combined product for the science target. The file name is
source-based, using the product name specified in the ASN file, e.g.
"jw86073-a3001_t001_nircam_f140m-maskbar_i2d.fits."
