NIRSpec Calibration Reference Files

This page provides information on the reference files used by the JWST pipeline to process NIRSpec data. The information is presented by pipeline stages. Details on the pipeline flow and steps, files format and their usage are accesible in the linked pages.

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The JWST NIRSpec instrument offers 4 science observing modes that are automatically processed by the JWST pipeline: multi-object spectroscopy with the micro-shutter array, integral field spectroscopy, fixed slits spectroscopy and bright object time-series (BOTS) spectroscopy. The following sections provide information on the NIRSpec-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). All processing steps in CALDETECTOR1, with the exception of Group Scale Correction, are applied to every NIRSpec exposure.To achieve that several the diverse steps in the correspondent NIR pipeline flow use the following reference files:


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

Pipeline stepReference files usedUsability notes

Group Scale Processing

Step does not use any reference file.Pipeline step applied only in data using NRS IRS2 readout mode.
Data Quality Initialization

Bad pixel mask: jwst_nirspec_mask_xxxx.fits


Saturation check

Saturation mask: jwst_nirspec_saturation_xxxx.fits


Interpixel Capacitance Deconvolutionjwst_nirspec_ipc_xxxx.fits

Step included in the pipeline, but disabled by default.

 Pipeline step not applied in BOTS observations

Superbias Subtraction

Bias file: jwst_nirspec_superbias_xxxx.fits


Reference Pixels Correction

Ref. pixel file: jwst_nirspec_refpix_xxxx.fits

Used in IRS2 readout mode.
Linearity Correction

Lin corre file: jwst_nirspec_linearity_xxxx.fits


Persistence correction

Persistence Saturation:

jwst_nirspec_persat_xxxx.fits

Traps Density:

jwst_nirspec_trapdensity_xxxx.fits

Trap Pars:

jwst_nirspec_trappars_xxxx.fits

Pipeline step not applied in BOTS observations
Dark Subtraction

Dark file: jwst_nirspec_dark_xxxx.fits


Jump Detection

Gain: jwst_nirspec_gain_xxxx.fits

Readnoise: jwst_nirspec_readnoise_xxxx.fits


Ramp Fit

Gain: jwst_nirspec_gain_xxxx.fits

Readnoise: jwst_nirspec_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

Although NIRSpec is primarily an spectrometer, there are several instances in which it is taking images (e.g. target acquisition, and confirmation images). These images also need to be processed by CALWEBB_IMAGE2 so the WCS information, needed later to apply distortion solution, is properly populated. For NIRSpec some of the standard calibration steps of this pipeline stage (e.g. flux calibration) are not applied. Details on the pipeline steps flow are given here.


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

Pipeline step
Reference files used
Usability notes
Assign WCS Information

Camera: jwst_nirspec_camera_xxxx.asdf

Colimator: jwst_nirspec_collimator_xxxx.asdf

Disperser: jwst_nirspec_disperser_xxxx.asdf

Fore: jwst_nirspec_fore_xxxx.asdf

FPA: jwst_nirspec_fpa_xxxx.asdf

IFUfore: jwst_nirspec_ifufore_xxxx.asdf

IFUpost: jwst_nirspec_ifupost_xxxx.asdf

IFUslicer: jwst_nirspec_msa_xxxx.asdf

MSA: jwst_nirspec_msa_xxxx.asdf

OTE: jwst_nirspec_ote_xxxx.asdf

Wavelength range: jwst_nirspec_wavelengthrange_xxxx.asdf

Verify that these are all used by the imaging data


Flat Field Correction

Dflat: jwst_nirspec_dflat_xxxx.fits

Need to confirm reference file


Rectify 2D imageStep does not use any reference file.



CALWEBB_SPEC2 reference files

This step process Individual exposures from the spectroscopic modes from counts/sec to absolute flux and wavelength units.  Nominally, this stage works on individual exposures. Details on the pipeline flow are given here.


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

Pipeline step
Reference files used
Usability notes
Assign WCS Information

Camera: jwst_nirspec_camera_xxxx.asdf

Colimator: jwst_nirspec_collimator_xxxx.asdf

Disperser: jwst_nirspec_disperser_xxxx.asdf

Fore: jwst_nirspec_fore_xxxx.asdf

FPA: jwst_nirspec_fpa_xxxx.asdf

IFUfore: jwst_nirspec_ifufore_xxxx.asdf

IFUpost: jwst_nirspec_ifupost_xxxx.asdf

IFUslicer: jwst_nirspec_msa_xxxx.asdf

MSA: jwst_nirspec_msa_xxxx.asdf

OTE: jwst_nirspec_ote_xxxx.asdf

Wavelength range: jwst_nirspec_wavelengthrange_xxxx.asdf


Background SubtractionStep does not require any reference file.
Imprint SubtractionStep does not require any reference file.Step applied to NIRSpec MOS and IFU data.
MSA failed open flagging

jwst_nirspec_msaoper_xxxx.json

Step applied to NIRSpec MOS and Fixed Slit data
Extract 2d spectrajwst_nirspec_wavecorr_xxxx.asdf
Step applied to NIRSpec Fixed Slit and MOS data.
Flat Field

Sflat: jwst_nirspec_sflat_xxxx.fits

Fflat: jwst_nirspec_fflat_xxxx.fits

Dflat: jwst_nirspec_dflat_xxxx.fits


Point vs Extended DecisionStep does not require any reference file
Source Type DeterminationStep does not require any reference file.
Photometric Correction

Photom: jwst_nirspec_photom_xxxx.fits

Area: jwst_nirspec_area_xxxx.fits


ResampleStep does not require any reference file.Step applied to NIRSpec Fixed Slit and MOS data.
Cube BuildNo reference files are read in this step. The necessary information is already provided by the "Assign WCS information" step.Step applied to NIRSpec IFU data.
Extract 1d spectrajwst_nirspec_extract1d_xxxx.json



CALWEBB_SPEC3

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


Table 4. NIRSpec reference files used by the JWST pipeline module calwebb_spec3

Pipeline step
Reference files used
Usability notes
Master Background Sub.Step does not use any reference file.
Outlier DetectionStep does not use any reference file.
Create Exp Level ProductsStep does not use any reference file.
Cube CreationStep does not use any reference file.

Extract 1d spectra

jwst_nirspec_extract1d_xxxx.json  



CALWEBB_TSO3

This pipeline stage processes individual exposures taken in the Time Series Observation (TSO) modes.


Table 5. NIRSpec reference files used by the JWST pipeline module calwebb_tso3

Pipeline step
Reference files used
Usability notes
Outlier DetectionStep does not use any reference file.
TSO Background SubtractionStep does not use any reference file.Not used by baseline pipeline.
Create Exp Level ProductsStep does not use any reference file.
Extract 1D SpectrumStep does not use any reference file.
White-Light PhotometryStep does not use any reference file.



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