Science products

The following sections describe the format and contents of each of the JWST FITS science products. Things to note in the descriptions include:

  • Not all FITS extensions occur in every data product of a given type. Many are either optional or dependent on the instrument or observing mode. Such optional extensions are noted with an asterisk in the tables below.

  • Because some extensions are optional, as well as the fact that the exact ordering of the extensions is not guaranteed, the FITS HDU index numbers of a given extension type can vary from one product to another. The only guarantee is that the SCI extension, containing the actual pixel values, will always be the first FITS extension (HDU=1). Other common extensions, like DQ and ERR, usually immediately follow the SCI, but the order is not guaranteed. Hence HDU index numbers are not listed for many extension types, because they can vary.

Uncalibrated raw data: uncal

Exposure raw data products are designated by a file name suffix of “uncal.” These files usually contain only the raw detector pixel values from an exposure, with the addition of some table extensions containing various types of meta data associated with the exposure. Additional extensions can be included for certain instruments and readout types, as noted below. The FITS file structure is as follows.

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

uint16

ncols x nrows x ngroups x nints

2

GROUP

BINTABLE

N/A

variable

3

INT_TIMES

BINTABLE

N/A

nints (rows) x 7 cols

ZEROFRAME*

IMAGE

uint16

ncols x nrows x nints

REFOUT*

IMAGE

uint16

ncols/4 x nrows x ngroups x nints

ASDF

BINTABLE

N/A

variable

  • SCI: 4-D data array containing the raw pixel values. The first two dimensions are equal to the size of the detector readout, with the data from multiple groups (NGROUPS) within each integration stored along the 3rd axis, and the multiple integrations (NINTS) stored along the 4th axis.

  • GROUP: A table of meta data for some (or all) of the data groups.

  • INT_TIMES: A table of begining, middle, and end time stamps for each integration in the exposure.

  • ZEROFRAME: 3-D data array containing the pixel values of the zero-frame for each integration in the exposure, where each plane of the cube corresponds to a given integration. Only appears if the zero-frame data were requested to be downlinked separately.

  • REFOUT: The MIRI detector reference output values. Only appears in MIRI exposures.

  • ADSF: The data model meta data.

This FITS file structure is the result of serializing a Level1bModel, but can also be read into a RampModel, in which case zero-filled ERR, GROUPDQ, and PIXELDQ data arrays will be created and stored in the model, having array dimensions based on the shape of the SCI array (see RampModel).

Ramp data: ramp

As raw data progress through the calwebb_detector1 pipeline they are stored internally in a RampModel. This type of data model is serialized to a ramp type FITS file on disk. The original detector pixel values (in the SCI extension) are converted from integer to floating-point data type. The same is true for the ZEROFRAME and REFOUT data extensions, if they are present. An ERR array and two types of data quality arrays are also added to the product. The FITS file layout is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows x ngroups x nints

2

PIXELDQ

IMAGE

uint32

ncols x nrows

3

GROUPDQ

IMAGE

uint8

ncols x nrows x ngroups x nints

4

ERR

IMAGE

float32

ncols x nrows x ngroups x nints

ZEROFRAME*

IMAGE

float32

ncols x nrows x nints

GROUP

BINTABLE

N/A

variable

INT_TIMES

BINTABLE

N/A

nints (rows) x 7 cols

REFOUT*

IMAGE

uint16

ncols/4 x nrows x ngroups x nints

ASDF

BINTABLE

N/A

variable

  • SCI: 4-D data array containing the pixel values. The first two dimensions are equal to the size of the detector readout, with the data from multiple groups (NGROUPS) within each integration stored along the 3rd axis, and the multiple integrations (NINTS) stored along the 4th axis.

  • PIXELDQ: 2-D data array containing DQ flags that apply to all groups and all integrations for a given pixel (e.g. a hot pixel is hot in all groups and integrations).

  • GROUPDQ: 4-D data array containing DQ flags that pertain to individual groups within individual integrations, such as the point at which a pixel becomes saturated within a given integration.

  • ERR: 4-D data array containing uncertainty estimates on a per-group and per-integration basis.

  • ZEROFRAME: 3-D data array containing the pixel values of the zero-frame for each integration in the exposure, where each plane of the cube corresponds to a given integration. Only appears if the zero-frame data were requested to be downlinked separately.

  • GROUP: A table of meta data for some (or all) of the data groups.

  • INT_TIMES: A table of begining, middle, and end time stamps for each integration in the exposure.

  • REFOUT: The MIRI detector reference output values. Only appears in MIRI exposures.

  • ADSF: The data model meta data.

Countrate data: rate and rateints

Countrate products are produced by applying the ramp_fitting step to the integrations within an exposure, in order to compute count rates from the original accumulating signal ramps. For exposures that contain multiple integrations (NINTS > 1) this is done in two ways, which results in two separate products. First, countrates are computed for each integration within the exposure, the results of which are stored in a rateints product. These products contain 3-D data arrays, where each plane of the data cube contains the countrate image for a given integration.

The results for each integration are also averaged together to form a single 2-D countrate image for the entire exposure. These resuls are stored in a rate product.

The FITS file structure for a rateints product is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows x nints

2

ERR

IMAGE

float32

ncols x nrows x nints

3

DQ

IMAGE

uint32

ncols x nrows x nints

4

INT_TIMES

BINTABLE

N/A

nints (rows) x 7 cols

5

VAR_POISSON

IMAGE

float32

ncols x nrows x nints

6

VAR_RNOISE

IMAGE

float32

ncols x nrows x nints

7

ASDF

BINTABLE

N/A

variable

  • SCI: 3-D data array containing the pixel values, in units of DN/s. The first two dimensions are equal to the size of the detector readout, with the data from multiple integrations stored along the 3rd axis.

  • ERR: 3-D data array containing uncertainty estimates on a per-integration basis. These values are based on the combined VAR_POISSON and VAR_RNOISE data (see below), given as standard deviation.

  • DQ: 3-D data array containing DQ flags. Each plane of the cube corresponds to a given integration.

  • INT_TIMES: A table of begining, middle, and end time stamps for each integration in the exposure.

  • VAR_POISSON: 3-D data array containing the per-integration variance estimates for each pixel, based on Poisson noise only.

  • VAR_RNOISE: 3-D data array containing the per-integration variance estimates for each pixel, based on read noise only.

  • ADSF: The data model meta data.

These FITS files are compatitable with the CubeModel data model.

The FITS file structure for a rate product is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows

2

ERR

IMAGE

float32

ncols x nrows

3

DQ

IMAGE

uint32

ncols x nrows

4

VAR_POISSON

IMAGE

float32

ncols x nrows x nints

5

VAR_RNOISE

IMAGE

float32

ncols x nrows x nints

6

ASDF

BINTABLE

N/A

variable

  • SCI: 2-D data array containing the pixel values, in units of DN/s.

  • ERR: 2-D data array containing uncertainty estimates for each pixel. These values are based on the combined VAR_POISSON and VAR_RNOISE data (see below), given as standard deviation.

  • DQ: 2-D data array containing DQ flags for each pixel.

  • VAR_POISSON: 2-D data array containing the variance estimate for each pixel, based on Poisson noise only.

  • VAR_RNOISE: 2-D data array containing the variance estimate for each pixel, based on read noise only.

  • ADSF: The data model meta data.

These FITS files are compatible with the ImageModel data model.

Note that the INT_TIMES table does not appear in rate products, because the data have been averaged over all integrations and hence the per-integration time stamps are no longer relevant.

Background-subtracted data: bsub and bsubints

The calwebb_image2 and calwebb_spec2 pipelines have the capability to perform background subtraction on countrate data. In its simplest form, this consists of subtracting background exposures or a CRDS background reference image from science images. This operation is performed by the background step in the stage 2 pipelines. If the pipeline parameter save_bsub is set to True, the result of the background subtraction step will be saved to a file. Because this is a direct image-from-image operation, the form of the result is identical to input. If the input is a rate product, the background-subtracted result will be a bsub product, which has the exact same structure as the rate product described above. Similarly, if the input is a rateints product, the background-subtracted result will be saved to a bsubints product, with the exact same structure as the rateints product described above.

Calibrated data: cal and calints

Single exposure calibrated products duplicate a lot of the format and content of countrate products. There are two different high-level forms of calibrated products: one containing results for all integrations in an exposure (calints) and one for results averaged over all integrations (cal). These products are the main result of Stage 2 pipelines like calwebb_image2 and calwebb_spec2. There are many additional types of extensions that only appear for certain observing modes or instruments, especially for spectroscopic exposures.

The FITS file structure for a calints product is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows x nints

2

ERR

IMAGE

float32

ncols x nrows x nints

3

DQ

IMAGE

uint32

ncols x nrows x nints

INT_TIMES

BINTABLE

N/A

nints (rows) x 7 cols

VAR_POISSON

IMAGE

float32

ncols x nrows x nints

VAR_RNOISE

IMAGE

float32

ncols x nrows x nints

VAR_FLAT

IMAGE

float32

ncols x nrows x nints

AREA*

IMAGE

ncols x nrows

WAVELENGTH*

IMAGE

float32

ncols x nrows

ASDF

BINTABLE

N/A

variable

  • SCI: 3-D data array containing the pixel values, in units of surface brightness, for each integration.

  • ERR: 3-D data array containing uncertainty estimates for each pixel, for each integration. These values are based on the combined VAR_POISSON and VAR_RNOISE data (see below), given as standard deviation.

  • DQ: 3-D data array containing DQ flags for each pixel, for each integration.

  • INT_TIMES: A table of begining, middle, and end time stamps for each integration in the exposure.

  • VAR_POISSON: 3-D data array containing the variance estimate for each pixel, based on Poisson noise only, for each integration.

  • VAR_RNOISE: 3-D data array containing the variance estimate for each pixel, based on read noise only, for each integration.

  • VAR_FLAT: 2-D data array containing the variance estimate for each pixel, based on uncertainty in the flat-field.

  • AREA: 2-D data array containing pixel area values, added by the photom step, for imaging modes.

  • WAVELENGTH: 2-D data array of wavelength values for each pixel, for some spectroscopic modes.

  • ADSF: The data model meta data.

The FITS file structure for a cal product is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows

2

ERR

IMAGE

float32

ncols x nrows

3

DQ

IMAGE

uint32

ncols x nrows

4

VAR_POISSON

IMAGE

float32

ncols x nrows

5

VAR_RNOISE

IMAGE

float32

ncols x nrows

6

VAR_FLAT

IMAGE

float32

ncols x nrows

AREA*

IMAGE

float32

ncols x nrows

WAVELENGTH*

IMAGE

float32

ncols x nrows

PATHLOSS_PS*

IMAGE

float32

ncols x nrows

PATHLOSS_UN*

IMAGE

float32

ncols x nrows

BARSHADOW*

IMAGE

float32

ncols x nrows

ASDF

BINTABLE

N/A

variable

  • SCI: 2-D data array containing the pixel values, in units of surface brightness.

  • ERR: 2-D data array containing uncertainty estimates for each pixel. These values are based on the combined VAR_POISSON and VAR_RNOISE data (see below), given as standard deviation.

  • DQ: 2-D data array containing DQ flags for each pixel.

  • VAR_POISSON: 2-D data array containing the variance estimate for each pixel, based on Poisson noise only.

  • VAR_RNOISE: 2-D data array containing the variance estimate for each pixel, based on read noise only.

  • VAR_FLAT: 2-D data array containing the variance estimate for each pixel, based on uncertainty in the flat-field.

  • AREA: 2-D data array containing pixel area values, added by the photom step, for imaging modes.

  • WAVELENGTH: 2-D data array of wavelength values for each pixel, for some spectroscopic modes.

  • PATHLOSS_PS: 2-D data array of point-source pathloss correction factors, added by the pathloss step, for some spectroscopic modes.

  • PATHLOSS_UN: 1-D data array of uniform-source pathloss correction factors, added by the pathloss step, for some spectroscopic modes.

  • BARSHADOW: 2-D data array of NIRSpec MSA bar shadow correction factors, added by the barshadow step, for NIRSpec MOS exposures only.

  • ADSF: The data model meta data.

For spectroscopic modes that contain data for multiple sources, such as NIRSpec MOS, NIRCam WFSS, and NIRISS WFSS, there will be multiple tuples of the SCI, ERR, DQ, VAR_POISSON, VAR_RNOISE, etc. extensions, where each tuple contains the data for a given source or slit, as created by the extract_2d step. FITS “EXTVER” keywords are used in each extension header to segregate the multiple instances of each extension type by source.

Cosmic-Ray flagged data: crf and crfints

Several of the stage 3 pipelines, such as calwebb_image3 and calwebb_spec3, include the outlier detection step, which finds and flags outlier pixel values within calibrated images. The results of this process have the identical format and content as the input cal and calints products. The only difference is that the DQ arrays have been updated to contain CR flags. If the inputs are in the form of cal products, the CR-flagged data will be saved to a crf product, which has the exact same structure and content as the cal product described above. Similarly, if the inputs are calints products, the CR-flagged results will be saved to a crfints product, which has the same structure and content as the calints product described above.

Resampled 2-D data: i2d and s2d

Images and spectra that have been resampled by the resample step use a different set of data arrays than other science products. Resampled 2-D images are stored in i2d products and resampled 2-D spectra are stored in s2d products. The FITS file structure for i2d products is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows

2

CON

IMAGE

int32

ncols x nrows

3

WHT

IMAGE

float32

ncols x nrows

HDRTAB*

BINTABLE

N/A

variable

ASDF

BINTABLE

N/A

variable

  • SCI: 2-D data array containing the pixel values, in units of surface brightness.

  • CON: 2-D context image, which encodes information about which input images contribute to a specific output pixel.

  • WHT: 2-D weight image giving the relative weight of the output pixels (effectively a relative exposure time map).

  • HDRTAB: A table containing meta data (FITS keyword values) for all of the input images that were combined to produce the output image. Only appears when multiple inputs are used.

  • ADSF: The data model meta data.

The FITS file structure for s2d products is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows

2

CON

IMAGE

int32

ncols x nrows

3

WHT

IMAGE

float32

ncols x nrows

HDRTAB*

BINTABLE

N/A

variable

ASDF

BINTABLE

N/A

variable

  • SCI: 2-D data array containing the pixel values, in units of surface brightness.

  • CON: 2-D context image, which encodes information about which input images contribute to a specific output pixel.

  • WHT: 2-D weight image giving the relative weight of the output pixels (effectively a relative exposure time map).

  • HDRTAB: A table containing meta data (FITS keyword values) for all of the input images that were combined to produce the output image. Only appears when multiple inputs are used.

  • ADSF: The data model meta data.

For exposure-based products that contain spectra for more than one source or slit (e.g. NIRSpec MOS) there will be multiple tuples of the SCI, CON, and WHT extensions, one set for each source or slit. FITS “EXTVER” keywords are used in each extension header to segregate the multiple instances of each extension type by source.

Resampled 3-D (IFU) data: s3d

3-D IFU cubes created by the cube_build step are stored in FITS files with the following structure:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows x nwaves

2

ERR

IMAGE

float32

ncols x nrows x nwaves

3

DQ

IMAGE

int32

ncols x nrows x nwaves

4

WMAP

IMAGE

float32

ncols x nrows x nwaves

WCS-TABLE

BINTABLE

N/A

2 cols x 1 row

HDRTAB*

BINTABLE

N/A

variable

ASDF

BINTABLE

N/A

variable

  • SCI: 3-D data array containing the spaxel values, in units of surface brightness.

  • DQ: 3-D data array containing DQ flags for each spaxel.

  • ERR: 3-D data array containing uncertainty estimates for each spaxel.

  • WMAP: 3-D weight image giving the relative weight of the output spaxels.

  • WCS-TABLE: A table listing the wavelength to be associated with each plane of the third axis in the SCI, DQ, ERR, and WMAP arrays, in a format that conforms to the FITS spectroscopic WCS standards. Column 1 of the table (“nelem”) gives the number of wavelength elements listed in the table and column 2 (“wavelength”) is a 1-D array giving the wavelength values.

  • HDRTAB: A table containing meta data (FITS keyword values) for all of the input images that were combined to produce the output image. Only appears when multiple inputs are used.

  • ADSF: The data model meta data.

s3d products contain several unique meta data elements intended to aid in the use of these products in data analysis tools. This includes the following keywords located in the header of the FITS primary HDU:

  • FLUXEXT: A string value containing the EXTNAME of the extension containing the IFU flux data. Normally set to “SCI” for JWST IFU cube products.

  • ERREXT: A string value containing the EXTNAME of the extension containing error estimates for the IFU cube. Normally set to “ERR” for JWST IFU cube products.

  • ERRTYPE: A string value giving the type of error estimates contained in ERREXT, with possible values of “ERR” (error = standard deviation), “IERR” (inverse error), “VAR” (variance), and “IVAR” (inverse variance). Normally set to “ERR” for JWST IFU cube products.

  • MASKEXT: A string value containing the EXTNAME of the extension containing the Data Quality mask for the IFU cube. Normally set to “DQ” for JWST IFU cube products.

In addition, the following WCS-related keywords are included in the header of the “SCI” extension to support the use of the wavelength table contained in the “WCS-TABLE” extension. These keywords allow data analysis tools that are compliant with the FITS spectroscopic WCS standards to automatically recognize and load the wavelength information in the “WCS-TABLE” and assign wavelengths to the IFU cube data.

  • PS3_0 = ‘WCS-TABLE’: The name of the extension containing coordinate data for axis 3.

  • PS3_1 = ‘wavelength’: The name of the table column containing the coordinate data.

The coordinate data (wavelength values in this case) contained in the “WCS-TABLE” override any coordinate information normally computed from FITS WCS keywords like CRPIX3, CRVAL3, and CDELT3 for coordinate axis 3.

Extracted 1-D spectroscopic data: x1d and x1dints

Extracted spectral data produced by the extract_1d step are stored in binary table extensions of FITS files. The overall layout of the FITS file is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

EXTRACT1D

BINTABLE

N/A

variable

2

ASDF

BINTABLE

N/A

variable

  • EXTRACT1D: A 2-D table containing the extracted spectral data.

  • ADSF: The data model meta data.

Multiple “EXTRACT1D” extensions can be present if there is data for more than one source or if the file is an x1dints product. For x1dints products, there is one “EXTRACT1D” extension for each integration in the exposure.

The structure of the “EXTRACT1D” table extension is as follows:

Column Name

Data Type

Contents | Units

WAVELENGTH

float64

Wavelength values | \(\mu\) m

FLUX

float64

Flux values

Jy

ERROR

float64

Error values

Jy

SURF_BRIGHT

float64

Surface Brightness

MJy/sr

SB_ERROR

float64

Surf. Brt. errors

MJy/sr

DQ

uint32

DQ flags

N/A

BACKGROUND

float64

Background signal

MJy/sr

BERROR

float64

Background error

MJy/sr

NPIXELS

float64

Number of pixels

N/A

The table is constructed using a simple 2-D layout, using one row per extracted spectral element in the dispersion direction of the data (i.e. one row per wavelength bin). Note that for point sources observed with NIRSpec or NIRISS SOSS mode, it is not possible to express the extracted spectrum as surface brightness and hence the SURF_BRIGHT and SB_ERROR columns will be set to zero. NPIXELS gives the (fractional) number of pixels included in the source extraction region at each wavelength bin.

Combined 1-D spectroscopic data: c1d

Combined spectral data produced by the combine_1d step are stored in binary table extensions of FITS files. The overall layout of the FITS file is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

COMBINE1D

BINTABLE

N/A

variable

2

ASDF

BINTABLE

N/A

variable

  • COMBINE1D: A 2-D table containing the combined spectral data.

  • ADSF: The data model meta data.

The structure of the “COMBINE1D” table extension is as follows:

Column Name

Data Type

Contents

Units

WAVELENGTH

float64

Wavelength values

\(\mu\) m

FLUX

float64

Flux values

Jy

ERROR

float64

Error values

Jy

SURF_BRIGHT

float64

Surface Brightness

MJy/sr

SB_ERROR

float64

Surf. Brt. errors

MJy/sr

DQ

uint32

DQ flags

N/A

WEIGHT

float64

Sum of weights

N/A

N_INPUT

float64

Number of inputs

N/A

The table is constructed using a simple 2-D layout, using one row per extracted spectral element in the dispersion direction of the data (i.e. one row per wavelength bin).

Source catalog: cat

The source_catalog step contained in the calwebb_image3 pipeline detects and quantifies sources within imaging products. The derived data for the sources is stored in a cat product, which is in the form of an ASCII table in ECSV (Enhanced Character Separated Values) format. It is a flat text file, containing meta data header entries and the source data in a 2-D table layout, with one row per source.

Photometry catalog: phot

The tso_photometry step in the calwebb_tso3 pipeline produces light curve from TSO imaging observations by computing aperture photometry as a function of integration time stamp within one or more exposures. The resulting photometric data are stored in a phot product, which is in the form of an ASCII table in ECSV (Enhanced Character Separated Values) format. It is a flat text file, containing meta data header entries and the photometric data in a 2-D table layout, with one row per exposure integration.

White-light photometry catalog: whtlt

The white_light step in the calwebb_tso3 pipeline produces a light curve from TSO spectroscopic observations by computing the wavelength-integrated spectral flux as a function of integration time stamp within one or more exposures. The resulting data are stored in a whtlt product, which is in the form of an ASCII table in ECSV (Enhanced Character Separated Values) format. It is a flat text file, containing meta data header entries and the white-light flux data in a 2-D table layout, with one row per exposure integration.

Stacked PSF data: psfstack

The stack_refs step in the calwebb_coron3 pipeline takes a collection of PSF reference image and assembles them into a 3-D stack of PSF images, which results in a psfstack product. The psfstack product uses the CubeModel data model, which when serialized to a FITS file has the structure shown below.

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows x npsfs

2

DQ

IMAGE

uint32

ncols x nrows x npsfs

3

ERR

IMAGE

float32

ncols x nrows x npsfs

4

ASDF

BINTABLE

N/A

variable

  • SCI: 3-D data array containing a stack of 2-D PSF images.

  • DQ: 3-D data array containing DQ flags for each PSF image.

  • ERR: 3-D data array containing a stack of 2-D uncertainty estimates for each PSF image.

  • ADSF: The data model meta data.

Aligned PSF data: psfalign

The align_refs step in the calwebb_coron3 pipeline creates a 3-D stack of PSF images that are aligned to corresponding science target images. The resulting psfalign product uses the QuadModel data model, which when serialized to a FITS file has the structure and content shown below.

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows x npsfs x nints

2

DQ

IMAGE

uint32

ncols x nrows x npsfs x nints

3

ERR

IMAGE

float32

ncols x nrows x npsfs x nints

4

ASDF

BINTABLE

N/A

variable

  • SCI: 4-D data array containing a stack of 2-D PSF images aligned to each integration within a corresponding science target exposure. each integration.

  • DQ: 4-D data array containing DQ flags for each PSF image.

  • ERR: 4-D data array containing a stack of 2-D uncertainty estimates for each PSF image, per science target integration.

  • ADSF: The data model meta data.

PSF-subtracted data: psfsub

The klip step in the calwebb_coron3 pipeline subtracts an optimized combination of PSF images from each integration in a science target exposure. The resulting PSF-subtracted science exposure data uses the CubeModel data model, which when serialized to a FITS file has the structure shown below.

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

SCI

IMAGE

float32

ncols x nrows x nints

2

ERR

IMAGE

float32

ncols x nrows x nints

3

DQ

IMAGE

uint32

ncols x nrows x nints

4

INT_TIMES

BINTABLE

N/A

nints (rows) x 7 cols

5

VAR_POISSON

IMAGE

float32

ncols x nrows x nints

6

VAR_RNOISE

IMAGE

float32

ncols x nrows x nints

7

ASDF

BINTABLE

N/A

variable

  • SCI: 3-D data array containing a stack of 2-D PSF-subtracted science target images, one per integration.

  • ERR: 3-D data array containing a stack of 2-D uncertainty estimates for each science target integration.

  • DQ: 3-D data array containing DQ flags for each science target integration.

  • INT_TIMES: A table of begining, middle, and end time stamps for each integration in the exposure.

  • VAR_POISSON: 3-D data array containing the per-integration variance estimates for each pixel, based on Poisson noise only.

  • VAR_RNOISE: 3-D data array containing the per-integration variance estimates for each pixel, based on read noise only.

  • ADSF: The data model meta data.

AMI data: ami, amiavg, and aminorm

AMI derived data created by the ami_analyze, ami_average, and ami_normalize steps, as part of the calwebb_ami3 pipeline, are stored in FITS files that contain a mixture of images and binary table extensions. The output format of all three pipeline steps is the same, encapsulated within a AmiLgModel data model. The overall layout of the corresponding FITS files is as follows:

HDU

EXTNAME

HDU Type

Data Type

Dimensions

0

N/A

primary

N/A

N/A

1

FIT

IMAGE

float32

ncols x nrows

2

RESID

IMAGE

float32

ncols x nrows

3

CLOSURE_AMP

BINTABLE

float64

1 col x 35 rows

4

CLOSURE_PHA

BINTABLE

float64

1 col x 35 rows

5

FRINGE_AMP

BINTABLE

float64

1 col x 21 rows

6

FRINGE_PHA

BINTABLE

float64

1 col x 21 rows

7

PUPIL_PHA

BINTABLE

float64

1 col x 7 rows

8

SOLNS

BINTABLE

float64

1 col x 44 rows

9

ASDF

BINTABLE

N/A

variable

  • FIT: A 2-D image of the fitted model.

  • RESID: A 2-D image of the fit residuals.

  • CLOSURE_AMP: A table of closure amplitudes.

  • CLOSURE_PHA: A table of closure phases.

  • FRINGE_AMP: A table of fringe amplitudes.

  • FRINGE_PHA: A table of fringe phases.

  • PUPIL_PHA: A table of pupil phases.

  • SOLNS: A table of fringe coefficients.

  • ADSF: The data model meta data.