Reference Files

The dq_init step uses a MASK reference file.

A list of the allowed DQ values are:

Flags for the DQ, PIXELDQ, and GROUPDQ Arrays.

Bit

Value

Name

Description

0

1

DO_NOT_USE

Bad pixel. Do not use.

1

2

SATURATED

Pixel saturated during exposure

2

4

JUMP_DET

Jump detected during exposure

3

8

DROPOUT

Data lost in transmission

4

16

GW_AFFECTED_DATA

Data affected by the GW read window

5

32

PERSISTENCE

High persistence (was RESERVED_2)

6

64

AD_FLOOR

Below A/D floor (0 DN, was RESERVED_3)

7

128

OUTLIER

Detected as outlier in coadded image

8

256

UNRELIABLE_ERROR

Uncertainty exceeds quoted error

9

512

NON_SCIENCE

Pixel not on science portion of detector

10

1024

DEAD

Dead pixel

11

2048

HOT

Hot pixel

12

4096

WARM

Warm pixel

13

8192

LOW_QE

Low quantum efficiency

15

32768

TELEGRAPH

Telegraph pixel

16

65536

NONLINEAR

Pixel highly nonlinear

17

131072

BAD_REF_PIXEL

Reference pixel cannot be used

18

262144

NO_FLAT_FIELD

Flat field cannot be measured

19

524288

NO_GAIN_VALUE

Gain cannot be measured

20

1048576

NO_LIN_CORR

Linearity correction not available

21

2097152

NO_SAT_CHECK

Saturation check not available

22

4194304

UNRELIABLE_BIAS

Bias variance large

23

8388608

UNRELIABLE_DARK

Dark variance large

24

16777216

UNRELIABLE_SLOPE

Slope variance large (i.e., noisy pixel)

25

33554432

UNRELIABLE_FLAT

Flat variance large

26

67108864

RESERVED_5

27

134217728

RESERVED_6

28

268435456

UNRELIABLE_RESET

Sensitive to reset anomaly

29

536870912

RESERVED_7

30

1073741824

OTHER_BAD_PIXEL

A catch-all flag

31

2147483648

REFERENCE_PIXEL

Pixel is a reference pixel

MASK Reference File

reftype:

MASK

Data model:

MaskRefModel

The MASK reference file contains pixel-by-pixel DQ flag values that indicate problem conditions.

Reference Selection Keywords for MASK

CRDS selects appropriate MASK references based on the following keywords. MASK is not applicable for instruments not in the table.

Instrument

Metadata

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 Keywords for MASK

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

Attribute

Fully qualified path

Instruments

detector

model.meta.instrument.detector

WFI

Reference File Format

MASK reference files are ASDF format, with one data object. The format and content of the file is as follows:

Data

Object Type

Dimensions

Data type

dq

NDArray

4096 x 4096

uint32

The values in the dq array give the per-pixel flag conditions that are to be propagated into the science exposure’s pixeldq array. The dimensions of the dq array should be equal to the number of columns and rows in a full-frame readout of a given detector, including reference pixels.

The ASDF file contains a single dq array.