FORE Reference File (NIRSpec only)

REFTYPE

FORE

Data model

FOREModel

Reference Selection Keywords for FORE

CRDS selects appropriate FORE references based on the following keywords. FORE is not applicable for instruments not in the table. All keywords used for file selection are required.

Instrument

Keywords

NIRSpec

INSTRUME, EXP_TYPE, FILTER, 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

Reference File Format

The FORE reference file stores the transform through the Filter Wheel Assembly (FWA). It has two fields - “filter” and “model”. The transform through the FWA is chromatic. It is represented as a Polynomial of two variables whose coefficients are wavelength dependent. The compound model takes three inputs - x, y positions and wavelength.

filter

Filter name.

model

Transform through the Filter Wheel Assembly (FWA).