Reference File

The dark step uses a DARK reference file.

DARK Reference File

REFTYPE:

DARK

Data models:

DarkRefModel

The DARK reference file contains pixel-by-pixel and frame-by-frame dark current values for a given detector readout mode.

Reference Selection Keyword Attributes for DARK

CRDS selects appropriate DARK references based on the following keyword attributes. DARK is not applicable for instruments not in the table.

Instrument	Keyword Attributes
WFI	instrument, detector, 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 Keyword Attributes for DARK

In addition to the standard reference file keyword attributes listed above, the following keyword attributes are required in DARK reference files, because they are used as CRDS selectors (see Reference Selection Keyword Attributes for DARK):

Attribute	Fully qualified path	Instruments
detector	model.meta.instrument.detector	WFI

Reference File Format

DARK reference files are ASDF format, with 3 data arrays. The format and content of the file is as follows (see DarkRefModel):

Data	Array Type	Dimensions	Data type
data	NDArray	4096 x 4096 x ngroups	float32
err	NDArray	4096 x 4096 x ngroups	float32
dq	NDArray	4096 x 4096	uint32
dark_slope	NDArray	4096 x 4096	float32
dark_slope_err	NDArray	4096 x 4096	float32

The ASDF file contains a single set of data, err, dq, dark slope and dark slope error arrays.