calwebb_coron3: Stage 3 Coronagraphic Processing
- Class:
- 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 |
---|
The high-level processing provided by these steps is:
CR-flag all PSF and science target exposures
Accumulate all reference PSF images into a single product
Align every PSF image to the first science integration image
Compute an optimal PSF fit and subtract it from every science target image
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:
- 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 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:
- File suffix:
_crfints
If the outlier_detection 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:
- File suffix:
_psfstack
The data from each input PSF reference exposure are concatenated into a single combined 3D stack by the stack_refs 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.”
3D aligned PSF images
- Data model:
- File suffix:
_psfalign
All of the reference PSF images in the “_psfstack” product are aligned to the first science target integration and saved to a 3D “_psfalign” product by the align_refs 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.” In-flight data show that neither line-of-sight pointing drift nor PSF property changes are significant over the timescales relevant to JWST coronagraphic observations; therefore it’s sufficient to align the PSF images to the first science target integration rather than separately for each science target integration as was done in the pre-flight pipeline.
3D PSF-subtracted images
- Data model:
- File suffix:
_psfsub
For each science target exposure, the klip 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:
- File suffix:
_i2d
The resample 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.”