NIRSpec Dark Template Parameters
JWST's NIRSpec Dark template, available in the Astronomer’s Proposal Tool (APT), is used to obtain darks for the NIRSpec instrument.
Purple text indicates the parameter is Limited Access.
Boldface italics type indicates the name of an APT parameter or a value for a parameter.
Red text indicates restrictions on a parameter.
Black text indicates an important note.
Brown text indicates notes for the developers.
Green text indicates the name of the parameter used by Commanding.
Items in brackets - <value> - are required values.
Items in square brackets - [<value>] - are optional.
These parameters are required to obtain Dark observations. Note that this type of observation can be obtained as a parallel to normal science observations.
For developers: users can specify one or more combinations of the parameters below for DARKs.
The following parameters are used to define NIRSpec Dark observations.
| Field | Details | Value | Notes |
|---|---|---|---|
| General Information | |||
| Observation Number | assign observation number | number | |
| Observation Label | provide observation label | text | optional |
| Observation Comments | provide observation comments | text | optional |
| Special Requirements | specify special requirements | choose from list | if needed |
| Template specific information | |||
| Subarray | select subarray | choose from list | |
| Readout Pattern | select readout pattern | choose from list | |
| Grating | select grating | choose from list | |
| Number of Groups/Integration | specify number of groups/integration | number | |
| Number of Integrations/Exposure | specify number of integrations/exposure | number | |
| Number of Exposures/Dither | specify the number of times to repeat the dark exposure/dither | number | |
General information
The following parameters are generic to all templates, and are not discussed in this article: Observation Number, Observation Label, Observation Comments, and Special Requirements.
Subarray
SUBARRAY [SUBARRAY] = FULL (default), ALLSLITS, SUBS200A1, SUBS200A2, SUBS200B1, SUBS400A1, SUB2048, SUB1024A, SUB1024B, SUB512
This parameter specifies the subarray that is to be read out for each detector.
Exposure Specification
For each exposure, specify the READOUT PATTERN, GRATING, NUMBER OF GROUPS/INTEGRATION, NUMBER OF INTEGRATIONS/EXPOSURE, and NUMBER OF EXPOSURES/DITHER.
Readout Pattern
READOUT PATTERN [READOUT PATTERN] = NRS, NRSRAPID, NRSIRS2, NRSIRS2RAPID
This field specifies the readout pattern to be used to obtain the data.
Note that there is a 100 second overhead associated with switching between IRS2 and non-IRS2 readout patterns in an observation.
Note that NUMBER OF GROUPS/INTEGRATION x NUMBER OF INTEGRATIONS/EXPOSURE must be less than 256 for NRISIRS2 and 1024 for NRSIRS2RAPID.
Note for developers: If there is interleaving of IRS2 and non-IRS2 readout patterns, issue a warning alerting the user to the 100 seconds overhead.
JWST's NIRSpec Dark template, available in the Astronomer’s Proposal Tool (APT), is used to obtain darks for the NIRSpec instrument.
Purple text indicates the parameter is Limited Access.
Boldface italics type indicates the name of an APT parameter or a value for a parameter.
Red text indicates restrictions on a parameter.
Black text indicates an important note.
Brown text indicates notes for the developers.
Green text indicates the name of the parameter used by Commanding.
Items in brackets - <value> - are required values.
Items in square brackets - [<value>] - are optional.
These parameters are required to obtain Dark observations. Note that this type of observation can be obtained as a parallel to normal science observations.
For developers: users can specify one or more combinations of the parameters below for DARKs.
The following parameters are used to define NIRSpec Dark observations.
| Field | Details | Value | Notes |
|---|---|---|---|
| General Information | |||
| Observation Number | assign observation number | number | |
| Observation Label | provide observation label | text | optional |
| Observation Comments | provide observation comments | text | optional |
| Special Requirements | specify special requirements | choose from list | if needed |
| Template specific information | |||
| Subarray | select subarray | choose from list | |
| Readout Pattern | select readout pattern | choose from list | |
| Grating | select grating | choose from list | |
| Number of Groups/Integration | specify number of groups/integration | number | |
| Number of Integrations/Exposure | specify number of integrations/exposure | number | |
| Number of Exposures/Dither | specify the number of times to repeat the dark exposure/dither | number | |
General information
The following parameters are generic to all templates, and are not discussed in this article: Observation Number, Observation Label, Observation Comments, and Special Requirements.
Subarray
SUBARRAY [SUBARRAY] = FULL (default), ALLSLITS, SUBS200A1, SUBS200A2, SUBS200B1, SUBS400A1, SUB2048, SUB1024A, SUB1024B, SUB512
This parameter specifies the subarray that is to be read out for each detector.
Exposure Specification
For each exposure, specify the READOUT PATTERN, GRATING, NUMBER OF GROUPS/INTEGRATION, NUMBER OF INTEGRATIONS/EXPOSURE, and NUMBER OF EXPOSURES/DITHER.
Readout Pattern
READOUT PATTERN [READOUT PATTERN] = NRS, NRSRAPID, NRSIRS2, NRSIRS2RAPID
This field specifies the readout pattern to be used to obtain the data.
Note that there is a 100 second overhead associated with switching between IRS2 and non-IRS2 readout patterns in an observation.
Note that NUMBER OF GROUPS/INTEGRATION x NUMBER OF INTEGRATIONS/EXPOSURE must be less than 256 for NRISIRS2 and 1024 for NRSIRS2RAPID.
Note for developers: If there is interleaving of IRS2 and non-IRS2 readout patterns, issue a warning alerting the user to the 100 seconds overhead.
Grating
GRATING [GRATING] = G140M, G235M, G395M, G140H, G235H, G395H, PRISM, MIRROR
The GRATING selection configures the location of the SUBARRAY on the detector. No matter which GRATING is selected, G140H is always used on board. GRATING is not available when SUBARRAY=FULL.
Number of Groups/Integration
NUMBER OF GROUPS/INTEGRATION [NGROUPS] specifies the number of groups in an integration.
Number of Integrations/Exposure
NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the integration is performed.
Number of Exposures/Dither
NUMBER OF EXPOSURES/DITHER [NEXP] specifies the number of times the Dark exposure is performed; the range is 1-50.