REGIONS Reference File (MIRI only)

REFTYPE:

REGIONS

Data model:

RegionsModel

Reference Selection Keywords for REGIONS

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

Instrument	Keywords
MIRI	INSTRUME, DETECTOR, EXP_TYPE, CHANNEL, BAND, 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 IFU takes a region reference file that defines the pixels on the detector that map to the sky and which IFU slice they correspond to. The reference file is a three-dimensional array measuring 1032 x 1024 x 9. Each of the nine planes within the array represents a two-dimensional detector image for which each pixel has a value indicating the slice to which it belongs. The nine planes each correspond to different throughput thresholds ranging from 10% - 90%; these differ slightly in the effective along-slice size.

channel:

The MIRI channels in the observation, e.g. “12”.

band:

The band for the observation (one of “LONG”, “MEDIUM”, “SHORT”).

regions:

An array with the size of the MIRI MRS image where pixel values map to the MRS slice number. 0 indicates a pixel is not within any slice.