Reference Files

The residual_fringe step uses the FRINGEFREQ reference file.

FRINGEFREQ reference file

REFTYPE

FRINGEFREQ

Data models

FringeFreqModel

The FRINGEFREQ reference files contain parameter values used to correct MIRI MRS images for residual fringes that remain after applying the fringe flat.

Reference Selection Keywords for FRINGEFREQ

CRDS selects appropriate FRINGEFREQ reference file based on the following keywords. FRINGEFREQ is not applicable for instruments not in the table.

Instrument

Keywords

MIRI

INSTRUME, EXP_TYPE, DETECTOR, DATE-OBS, TIME-OBS

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 FRINGEFREQ

In addition to the standard reference file keywords listed above, the following keywords are required in FRINGEFREQ reference files, because they are used as CRDS selectors (see Reference Selection Keywords for FRINGEFREQ):

Keyword

Data Model Name

DETECTOR

model.meta.instrument.detector

EXP_TYPE

model.meta.exposure.type

Reference File Format

The FRINGEFREQ reference files are FITS format, with 4 BINTABLE extensions. The FITS primary data array is assumed to be empty. The format and content of the FRINGEFREQ reference file is

EXTNAME

XTENSION

Dimensions

RFC_FREQ_SHORT

BINTABLE

TFIELDS = 7

RFC_FREQ_MEDIUM

BINTABLE

TFIELDS = 7

RFC_FREQ_LONG

BINTABLE

TFIELDS = 7

MAX_AMP

BINTABLE

TFIELDS = 2

The formats of the individual table extensions are listed below.

Table

Column

Data type

Units

RFC_FREQ_SHORT

SLICE

double

N/A

FFREQ

double

cm-1

DFFREQ

double

cm-1

MIN_NFRIGES

int

N/A

MAX_NFRINGES

int

N/A

MIN_SNR

double

cm-1

PGRAM_RES

double

cm-1

FRC_FREQ_MEDIUM

SLICE

double

N/A

FFREQ

double

cm-1

DFFREQ

double

cm-1

MIN_NFRIGES

int

N/A

MAX_NFRINGES

int

N/A

MIN_SNR

double

cm-1

PGRAM_RES

double

cm-1

RFC_FREQ_LONG

SLICE

double

N/A

FFREQ

double

cm-1

DFFREQ

double

cm-1

MIN_NFRIGES

int

N/A

MAX_NFRINGES

int

N/A

MIN_SNR

double

cm-1

PGRAM_RES

double

cm-1

MAX_AMP

WAVELENGTH

double

micron

AMPLITUDE

double

N/A

These reference files contain tables for each MIRI band giving the fringe frequencies and other parameters for each band to fit and remove residual fringes.

The reference table descriptions:

  • RFC_FREQ_SHORT table contains the fringe frequencies and parameters for the SHORT band.

  • RFC_FREQ_MEDIUM table contains the fringe frequencies and parameters for the MEDIUM band.

  • RFC_FREQ_LONG table contains the fringe frequencies and parameters for the LONG band.

  • MAX_AMP table contains a wavelength dependent maximum amplitude which is use for feature identification and fit rejection.