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.