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).