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James Webb Space Telescope User Documentation

 

 

JWST's NIRSpec Dark template, available in the Astronomer’s Proposal Tool (APT), is used to obtain darks for the NIRSpec instrument.

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.

FieldDetailsValueNotes
General Information
Observation Numberassign observation numbernumber 
Observation Labelprovide observation labeltextoptional
Observation Commentsprovide observation commentstextoptional
Special Requirementsspecify special requirementschoose from listif needed
Template specific information
Subarrayselect subarraychoose from list 
Readout Patternselect readout patternchoose from list 
Gratingselect gratingchoose from list 
Number of Groups/Integrationspecify number of groups/integrationnumber 
Number of Integrations/Exposurespecify number of integrations/exposurenumber 
Number of Exposures/Ditherspecify the number of times to repeat the dark exposure/dithernumber 

 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.

(warning)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

This field specifies the grating. This parameter is necessary because GRATING defines the location of the subarray on the detector. If SUBARRAY is FULL this field is not available.  

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; (warning)the range is 1-50.

Keywords

NIRSpec Dark Template

NIRSpec Dark Template Parameters

Format definitions

Boldface italics type indicates the name of an APT parameter or a value for a parameter.

Brown text indicates notes for the developers.

Green text indicates the name of the parameter used by Commanding.

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JWST Proposal Parameters