Reference Files¶
The flat_field
step uses a FLAT reference file.
FLAT Reference File¶
- REFTYPE:
FLAT
- Data model:
roman_datamodels.datamodels.FlatRefModel
The FLAT reference file contains pixel-by-pixel detector response values. It is used.
Reference Selection Keywords for FLAT¶
CRDS selects appropriate FLAT references based on the following attributes. FLAT is not applicable for instruments not in the table. Non-standard attributes used for file selection are required.
Instrument |
Metadata |
---|---|
WFI |
instrument, detector, optical_element, date, time |
Standard ASDF metadata¶
The following table lists the attributes that are required to be present in all reference files. The first column shows the attribute in the ASDF reference file headers, which is the same as the name within the data model meta tree (second column). The second column gives the roman data model name for each attribute, which is useful when using data models in creating and populating a new reference file.
Attribute |
Fully Qualified Path |
---|---|
author |
model.meta.author |
model_type |
model.meta.model_type |
date |
model.meta.date |
description |
model.meta.description |
instrument |
model.meta.instrument.name |
reftype |
model.meta.reftype |
telescope |
model.meta.telescope |
useafter |
model.meta.useafter |
NOTE: More information on standard required attributes can be found here: Standard ASDF metadata
Type Specific Keywords for FLAT¶
In addition to the standard reference file attributes listed above, the following attributes are required in FLAT reference files, because they are used as CRDS selectors (see Reference Selection Keywords for FLAT):
Attribute |
Fully qualified path |
Instruments |
---|---|---|
detector |
model.meta.instrument.detector |
WFI |
exptype |
model.meta.exposure.type |
|
optical_element |
model.meta.instrument.optical_element |
Reference File Format¶
FLAT reference files are ASDF format, with 3 data arrays. The format and content of the file is as follows:
Data |
Array Type |
Dimensions |
Data type |
---|---|---|---|
data |
NDArray |
4096 x 4096 |
float32 |
err |
NDArray |
4096 x 4096 |
float32 |
dq |
NDArray |
4096 x 4096 |
uint32 |
The ASDF file contains a single set of data, err, and dq arrays.