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.


 Format definitions...

Purple text indicates the parameter is Limited Access.

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

(warning)Red text indicates restrictions on a parameter.

(red star) 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.

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.

Change log

 Click here to expand...

Version 3 (April 19, 2019)

  1. Editorial change (moved change log to main article)


Version 2 (September 5, 2017)

  1. PR 88059 - added grating field
  2. PR 88968 - revised overhead time for switching between IRS and IRS2 readout patterns
  3. PR 88047 - added restriction on NGroups x NINTS for IRS2 readout pattern


Version 1 (June 15, 2017)

  1. This is the converted Word File from Chapter 39.
  2. PR 79394 - added Subarray parameter
  3. PR 87895 - revised names of Number of Groups and Integrations