Reference Files
The persistence step uses
TRAPDENSITY,
PERSAT, and
TRAPPARS reference files.
TRAPDENSITY Reference File
- REFTYPE:
TRAPDENSITY
- Data model:
The TRAPDENSITY reference file contains a pixel-by-pixel map of the trap density.
Reference Selection Keywords for TRAPDENSITY
CRDS selects appropriate TRAPDENSITY references based on the following keywords. TRAPDENSITY is not applicable for instruments not in the table. All keywords used for file selection are required.
Instrument |
Keywords |
|---|---|
FGS |
INSTRUME, DETECTOR, DATE-OBS, TIME-OBS |
NIRCam |
INSTRUME, DETECTOR, DATE-OBS, TIME-OBS |
NIRISS |
INSTRUME, DETECTOR, 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 TRAPDENSITY
In addition to the standard reference file keywords listed above, the following keywords are required in TRAPDENSITY reference files, because they are used as CRDS selectors (see Reference Selection Keywords for TRAPDENSITY):
Keyword |
Data Model Name |
|---|---|
DETECTOR |
model.meta.instrument.detector |
Reference File Format
TRAPDENSITY reference files are FITS format, with 2 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 |
DQ |
IMAGE |
2 |
ncols x nrows |
int |
DQ_DEF |
BINTABLE |
2 |
TFIELDS = 4 |
N/A |
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.
PERSAT Reference File
- REFTYPE:
PERSAT
- Data model:
The PERSAT reference file contains a pixel-by-pixel map of the persistence saturation (full well) threshold.
Reference Selection Keywords for PERSAT
CRDS selects appropriate PERSAT references based on the following keywords. PERSAT is not applicable for instruments not in the table. All keywords used for file selection are required.
Instrument |
Keywords |
|---|---|
FGS |
INSTRUME, DETECTOR, DATE-OBS, TIME-OBS |
NIRCam |
INSTRUME, DETECTOR, DATE-OBS, TIME-OBS |
NIRISS |
INSTRUME, DETECTOR, 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 PERSAT
In addition to the standard reference file keywords listed above, the following keywords are required in PERSAT reference files, because they are used as CRDS selectors (see Reference Selection Keywords for PERSAT):
Keyword |
Data Model Name |
|---|---|
DETECTOR |
model.meta.instrument.detector |
Reference File Format
PERSAT reference files are FITS format, with 2 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 |
DQ |
IMAGE |
2 |
ncols x nrows |
int |
DQ_DEF |
BINTABLE |
2 |
TFIELDS = 4 |
N/A |
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.
TRAPPARS Reference File
- REFTYPE:
TRAPPARS
- Data model:
The TRAPPARS reference file contains default parameter values used in the persistence correction.
Reference Selection Keywords for TRAPPARS
CRDS selects appropriate TRAPPARS references based on the following keywords. TRAPPARS is not applicable for instruments not in the table. All keywords used for file selection are required.
Instrument |
Keywords |
|---|---|
FGS |
INSTRUME, DETECTOR, DATE-OBS, TIME-OBS |
NIRCam |
INSTRUME, DETECTOR, DATE-OBS, TIME-OBS |
NIRISS |
INSTRUME, DETECTOR, 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 TRAPPARS
In addition to the standard reference file keywords listed above, the following keywords are required in TRAPPARS reference files, because they are used as CRDS selectors (see Reference Selection Keywords for TRAPPARS):
Keyword |
Data Model Name |
|---|---|
DETECTOR |
model.meta.instrument.detector |
Reference File Format
TRAPPARS reference files are FITS format, with 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 |
Dimensions |
|---|---|---|
TRAPPARS |
BINTABLE |
TFIELDS = 4 |
The format and contents of the table extension is as follows:
Column name |
Data type |
Description |
|---|---|---|
capture0 |
float |
Coefficient of exponential capture term |
capture1 |
float |
Minus the reciprocal of capture e-folding time |
capture2 |
float |
The “instantaneous” capture coefficient |
decay_param |
float |
Minus the reciprocal of decay e-folding time |
At the present time, there are no persistence reference files for MIRI and NIRSpec. CRDS will return “N/A” for the names of the reference files if the persistence step is run on MIRI or NIRSpec data, in which case the input will be returned unchanged, except that the primary header keyword S_PERSIS will will have been set to ‘SKIPPED’.