This page provides information on the reference files used by the JWST pipeline to process NIRCam data. The information is presented by pipeline stages. Details on the pipeline flow and steps, files format and their usage are provided in the specified links.


Introduction

The JWST NIRCam instrument offers 5 science observing modes that are automatically processed by the JWST pipeline: imaging, coronagraphic imaging, wide field slitless spectroscopy, time series imaging and grism time series. The following sections provide information on the NIRCam-specific reference files used by the pipeline, organised according to the different pipeline stages. In all cases xxxx replaces the version number of the file.

 


CALWEBB_DETECTOR1 reference files

This pipeline stage process the LVL1 up-the-ramp raw files and returns the level 2a files in units of (counts/sec). To achieve that several the diverse steps in the correspondent NIR pipeline flow use the following reference files:

Table 1. NIRCam reference files used by the JWST pipeline module calwebb_detector1.

CALDETECTOR1 pipeline step

Reference file used

Usability notes

Data Quality Initialization

 jwst_nircam_mask_xxxx.fits

One reference files per each detector, Full and subarray modes

 

Saturation check

jwst_nircam_saturation_xxxx.fits

 

Interpixel Capacitance Deconvolution

jwst_nircam_ipc_xxxx.fits

Step included in the pipeline, but disabled by default.

Pipeline step not applied to time series imaging data

Superbias Subtraction

jwst_nircam_superbias_xxxx.fits

 

Reference Pixels Correction

N/A. The correction uses reference pixels information stored in each exposure

 

Linearity Correction

jwst_nircam_linearity_xxxx.fits

 

Persistence correction

Persat: jwst_nircam_persat_xxxx.fits

Trap density: jwst_nircam_trapdensity_xxxx.fits

Trap pars: jwst_nircam_trappars_xxxx.fits

Pipeline step not applied to time series imaging data

Dark Subtraction

jwst_nircam_dark_xxxx.fits

 

Jump Detection

This pipeline step uses gain and readnoise information

Gain: jwst_nircam_gain_xxxx.fits

Read noise: jwst_nircam_readnoise_xxxx.fits

 

Ramp Fit

Gain: jwst_nircam_gain_xxxx.fits

Read noise: jwst_nircam_readnoise_xxxx.fits

 

 


CALWEBB_Dark

This pipeline branch is intended for use with dark exposures. It applies all of the same detector-level correction steps as CALWEBB_Slopes and uses the same refrence files, but stops just before the application of the dark subtraction step.

 


CALWEBB_IMAGE2 reference files

In this pipeline stage individual exposures from the imaging modes are processed from counts/sec to absolute flux units. Details on the pipeline steps flow are given here.

Table 2. NIRCam reference files used by the JWST pipeline module calwebb_image2.

Pipeline step

Reference file used

Usability notes

Assign WCS Information

Distortion file: jwst_nircam_distortion_xxxx.asdf

 

Background Subtraction

Step does not use any reference file.

Step applies to science data if the user requests a dedicated background image.

Not applied to Target Acquisition images.

Flat Field Correction

Flat field: jwst_nircam_flat_0105.fits

 

Flux Calibration

Photom: jwst_nircam_photom_0031.fits

Area: jwst_nircam_area_0001.fits

Not applied to Target Acquisition images.

Rectify 2D image

Step does not use any reference file.

 

 


CALWEBB_SPEC2 reference files

This pipeline stage process Individual exposures from the spectroscopic modes from counts/sec to absolute flux and wavelength units. Nominally, this stage works on individual exposures obtained for the NIRCam wide field slitless grism observations, but the steps are not yet implemented.

Table 3. NIRCam reference files used by the JWST pipeline module calwebb_spec2.

 

Pipeline step

 

 

Reference file used

 

 

Usability notes

 

Assign WCS Information

Distortion file: jwst_nircam_distortion_xxxx.asdf

Specwcs: File not available in CRDS

 

Background Subtraction

Step does not use any reference file.

 

Subwindow extraction

Step does not use any reference file.

 

Flat Field

Flat filed: jwst_nircam_flat_xxxx.fits

 

Point vs Extended Decision

Step does not require any reference file

 

Photometric Correction

Photom: jwst_nircam_photom_xxxx.fits

Area: jwst_nircam_area_xxxx.fits

 

Rectified 2D 3D product

  

 


CALWEBB_IMAGE3 reference files

Multiple exposures from the direct imaging modes (e.g., dither pattern or mosaic) are combined into a single rectified (distortion corrected) image. Details on the pipeline steps flow are given in this page.

Table 4. NIRCam reference files used by the JWST pipeline module calwebb_image3.

Pipeline step

Reference file used

Usability notes

Tweakreg Catalog

Step does not use any reference file.

 

Tweakreg

Step does not use any reference file.

 

Skymatch

Step does not use any reference file.

 

Outlier_detection

Step does not use any reference file.

 

Resample

jwst_nircam_drizpars_xxxx.fits

 

Source_catalog

Step does not use any reference file.

 

 


CALWEBB_SPEC3

Multiple individual spectroscopic exposures (i.e. dither patters or mosaics) are combined into a single rectified cube and/or extracted spectrum.

Table 5. NIRCam reference files used by the JWST pipeline module calwebb_spec3.

 

Pipeline step

 

 

Reference file used

 

 

Usability notes

 

Outlier Detection

Step does not require any extra reference file.

 

Create Exp Level Products

  

Cube Creation

Step does not use any reference file. 

 

Spectral Extraction 1D

  

 


CALWEBB_CORON3

This pipeline stage processes and combines multiple coronagraphic exposures.

Table 6. NIRCam reference files used by the JWST pipeline module calwebb_coron3.

Pipeline step

Reference file used

Usability notes

Assemble Ref PSFs

Step does not use any reference file, but reference PSFs.

 

Align Ref PSFs

Step does not use any reference file.

 

Background Matching

 

Not part of the baseline pipeline

Ref PSF Subtraction

Step does not use any reference file.

 

Outlier Detection

Step does not use any reference file.

 

Image Combination

Step does not use any reference file.

 

Create Exp Level Products

Step does not use any reference file.

 

Ancillary Science Products

 

Not part of the baseline pipeline

 


 







Last updated

Updated July 15, 2017

  • Tables 1, 3, 4, and 5


Published July 11, 2017


 

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Published March 2, 2017