Reference Files
The fringe step uses a FRINGE reference file.
FRINGE Reference File
- REFTYPE:
FRINGE
- Data model:
The FRINGE reference file contains pixel-by-pixel fringing correction values.
Reference Selection Keywords for FRINGE
CRDS selects appropriate FRINGE references based on the following keywords. FRINGE is not applicable for instruments not in the table. Non-standard keywords used for file selection are required.
Instrument |
Keywords |
|---|---|
MIRI |
INSTRUME, DETECTOR, 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
Type Specific Keywords for FRINGE
In addition to the standard reference file keywords listed above, the following keywords are required in FRINGE reference files, because they are used as CRDS selectors (see Reference Selection Keywords for FRINGE):
Keyword |
Data Model Name |
|---|---|
DETECTOR |
model.meta.instrument.detector |
BAND |
model.meta.instrument.band |
Reference File Format
FRINGE reference files are FITS format, with 3 IMAGE extensions and 1 BINTABLE extension. The FITS primary HDU does not contain a data array. The format and content of the file is as follows:
EXTNAME |
XTENSION |
NAXIS |
Dimensions |
Data type |
|---|---|---|---|---|
SCI |
IMAGE |
2 |
ncols x nrows |
float |
ERR |
IMAGE |
2 |
ncols x nrows |
float |
DQ |
IMAGE |
2 |
ncols x nrows |
integer |
DQ_DEF |
BINTABLE |
2 |
TFIELDS = 4 |
N/A |
The values in the SCI array give the correction values to be applied to
the science data.
Because MIRI MRS exposures are always full-frame, the image dimensions
should be 1032 x 1024.
The DQ_DEF extension contains the bit assignments used in the DQ array. It contains the following 4 columns:
TTYPE |
TFORM |
Description |
|---|---|---|
BIT |
integer |
The bit number, starting at zero |
VALUE |
integer |
The equivalent base-10 value of BIT |
NAME |
string |
The mnemonic name of the data quality condition |
DESCRIPTION |
string |
A description of the data quality condition |
NOTE: For more information on standard bit definitions see: Data Quality Flags.