Reference Files¶
The cube_build
step uses CUBEPAR reference file.
CUBEPAR reference file¶
 REFTYPE
CUBEPAR
 Data models
The CUBEPAR reference file contains parameter values used to construct the output IFU cubes.
Reference Selection Keywords for CUBEPAR¶
CRDS selects appropriate CUBEPAR references based on the following keywords. CUBEPAR is not applicable for instruments not in the table.
Instrument 
Keywords 

MIRI 
INSTRUME, EXP_TYPE, DATEOBS, TIMEOBS 
NIRSPEC 
INSTRUME, EXP_TYPE, OPMODE, DATEOBS, TIMEOBS 
Standard Keywords¶
The following table lists the keywords that are required to be present in all reference files. The first column gives the FITS keyword names. The second column gives the jwst data model name for each keyword, which is useful when using data models in creating and populating a new reference file. The third column gives the equivalent meta tag in ASDF reference file headers, which is the same as the name within the data model meta tree (second column).
FITS Keyword 
Data Model Name 
ASDF meta tag 

AUTHOR 
model.meta.author 
author 
DATAMODL 
model.meta.model_type 
model_type 
DATE 
model.meta.date 
date 
DESCRIP 
model.meta.description 
description 
FILENAME 
model.meta.filename 
N/A 
INSTRUME 
model.meta.instrument.name 
instrument: {name} 
PEDIGREE 
model.meta.pedigree 
pedigree 
REFTYPE 
model.meta.reftype 
reftype 
TELESCOP 
model.meta.telescope 
telescope 
USEAFTER 
model.meta.useafter 
useafter 
NOTE: More information on standard required keywords can be found here: Standard Required Keywords
Type Specific Keywords for CUBEPAR¶
In addition to the standard reference file keywords listed above, the following keywords are required in CUBEPAR reference files, because they are used as CRDS selectors (see Reference Selection Keywords for CUBEPAR):
Keyword 
Data Model Name 

EXP_TYPE 
model.meta.exposure.type 
MIRI Reference File Format¶
The MIRI CUBEPAR reference files are FITS format, with 5 BINTABLE extensions. The FITS primary data array is assumed to be empty. The format and content of the MIRI CUBEPAR reference file
EXTNAME 
XTENSION 
Dimensions 

CUBEPAR 
BINTABLE 
TFIELDS = 6 
CUBEPAR_MSM 
BINTABLE 
TFIELDS = 6 
MULTICHANNEL_MSM 
BINTABLE 
TFIELDS = 5 
CUBEPAR_EMSM 
BINTABLE 
TFIELDS = 5 
MULTICHANNEL_EMSM 
BINTABLE 
TFIELDS = 4 
MULTICHANNEL_DRIZ 
BINTABLE 
TFIELDS = 1 
NIRSPec Reference File Format¶
The NIRSpec CUBEPAR reference files are FITS format, with 9 BINTABLE extensions.
EXTNAME 
XTENSION 
Dimensions 

CUBEPAR 
BINTABLE 
TFIELDS = 6 
CUBEPAR_MSM 
BINTABLE 
TFIELDS = 6 
MULTICHAN_PRISM_MSM 
BINTABLE 
TFIELDS = 5 
MULTICHAN_MED_MSM 
BINTABLE 
TFIELDS = 5 
MULTICHAN_HIGH_MSM 
BINTABLE 
TFIELDS = 5 
CUBEPAR_EMSM 
BINTABLE 
TFIELDS = 5 
MULTICHAN_PRISM_EMSM 
BINTABLE 
TFIELDS = 4 
MULTICHAN_MED_EMSM 
BINTABLE 
TFIELDS = 4 
MULTICHAN_HIGH_EMSM 
BINTABLE 
TFIELDS = 4 
The formats of the individual table extensions are listed below, first for the MIRI reference file and then for NIRSpec.
Table 
Column 
Data type 
Units 

CUBEPAR 
CHANNEL 
shortint 
N/A 
BAND 
ch*6 
N/A 

WAVEMIN 
float 
microns 

WAVEMAX 
float 
microns 

SPAXELSIZE 
float 
arcseconds 

SPECTRALSTEP 
double 
microns 

CUBEPAR_MSM 
CHANNEL 
shortint 
N/A 
BAND 
ch*6 
N/A 

ROISPATIAL 
float 
arcseconds 

ROISPECTRAL 
double 
microns 

POWER 
double 
unitless 

SOFTRAD 
double 
unitless 

MULTICHANNEL_MSM 
WAVELENGTH 
double 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

POWER 
double 
unitless 

SOFTRAD 
double 
unitless 

CUBEPAR_EMSM 
CHANNEL 
shortint 
N/A 
BAND 
ch*6 
N/A 

ROISPATIAL 
float 
arcseconds 

ROISPECTRAL 
double 
microns 

SCALERAD 
double 
unitless 

MULTICHANNEL_EMSM 
WAVELENGTH 
double 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

SCALERAD 
double 
unitless 

MULTICHANNEL_DRIZ 
WAVELENGTH 
double 
microns 
Table 
Column 
Data type 
Units 

CUBEPAR 
DISPERSER 
ch*5 
N/A 
FILTER 
ch*6 
N/A 

WAVEMIN 
double 
microns 

WAVEMAX 
double 
microns 

SPAXELSIZE 
double 
arcseconds 

SPECTRALSTEP 
double 
microns 

CUBEPAR_MSM 
DISPERSER 
ch*5 
N/A 
FILTER 
ch*6 
N/A 

ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

POWER 
double 
unitless 

SOFTRAD 
double 
unitless 

MULTICHAN_PRISM_MSM 
WAVELENGTH 
double 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

POWER 
double 
unitless 

SOFTRAD 
double 
unitless 

MULTICHAN_MED_MSM 
WAVELENGTH 
float 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

POWER 
double 
unitless 

SOFTRAD 
double 
unitless 

MULTICHAN_HIGH_MSM 
WAVELENGTH 
float 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

POWER 
double 
unitless 

SOFTRAD 
double 
unitless 

CUBEPAR_EMSM 
DISPERSER 
ch*5 
N/A 
FILTER 
ch*6 
N/A 

ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

SCALERAD 
double 
unitless 

MULTICHAN_PRISM_EMSM 
WAVELENGTH 
double 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

SCALERAD 
double 
unitless 

MULTICHAN_MED_EMSM 
WAVELENGTH 
float 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

SCALERAD 
double 
unitless 

MULTICHAN_HIGH_EMSM 
WAVELENGTH 
float 
microns 
ROISPATIAL 
double 
arcseconds 

ROISPECTRAL 
double 
microns 

SCALERAD 
double 
unitless 
These reference files contain tables for each wavelength band giving the spatial and spectral size, and the size of the region of interest (ROI) to use to construct an IFU cube. If only one band is used to construct the IFU cube then the CUBEPAR and CUBEPAR_MSM or CUBE_EMSM tables are used. These types of cubes will have a linear  wavelength dimension. If more than one wavelength band is used to build the IFU cube then the MULTICHANNEL (MIRI) or MULTICHAN (NIRSPEC) tables are used o set the spectral and spatial roi size, and the wavelength dependent weighting function parameters. For multiband IFU cubes then the final spatial size will be the smallest one from the list of input bands and these cubes will have a nonlinear wavelength dimension.
The MIRI reference table descriptions:
CUBEPAR table contains the spatial and spectral cube sample size for each band.
CUBEPAR_MSM table contains the Modified Shepard Method (MSM) weighting values to use for each band.
MULTICHANNEL_MSM table is used for the MSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from several bands and the final output is to have an IFU cube of varying spectral scale.
CUBEPAR_EMSM table contains the Exponential Modified Shepard Method (EMSM) weighting values to use for each band.
MULTICHANNEL_EMSM table is used for the EMSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from several bands and the final output is to have an IFU cube of varying spectral scale.
MULTICHANNEL_DRIZ table is used for the DRIZZLE weighting and contains the wavelengths to use when IFU cubes are created from several bands and the final output is to have an IFU cube of varying spectral scale.
The NIRSPEC reference table descriptions:
CUBEPAR table contains the spatial and spectral cube sample size for each band.
CUBEPAR_MSM table contains the Modified Shepard Method (MSM) weighting values to use for each band.
MULTICHAN_PRISM_MSM table is used for the MSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from the grating prism and the final IFU Cube output has a varying spectral scale.
MULTICHAN_MED_MSM table is used for the MSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from the medium resolution grating and the final IFU Cube output has a varying spectral scale.
MULTICHAN_HIGH_MSM table is used for the MSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from the high resolution gratings and the final IFU Cube output has a varying spectral scale.
CUBEPAR_EMSM table contains the Exponential Modified Shepard Method (EMSM) weighting values to use for each band.
MULTICHAN_PRISM_EMSM table is used for the EMSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from the grating prism and the final IFU Cube output has a varying spectral scale.
MULTICHAN_MED_EMSM table is used for the EMSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from the medium resolution grating and the final IFU Cube output has a varying spectral scale.
MULTICHAN_HIGH_EMSM table is used for the EMSM weighting and contains the wavelengths and associated region of interest size to use when IFU cubes are created from the high resolution gratings and the final IFU Cube output has a varying spectral scale.