NIRSpec Imaging Template Parameters

JWST's NIRSpec Imaging template, available in the Astronomer’s Proposal Tool (APT), is used to obtain imaging observations for standalone engineering measurements.


 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.

The following parameters are required to obtain Imaging observations for standalone engineering measurements. These images may be used to check NIRSpec focus, evaluate MSA shutter performance, or for other diagnostic purposes. The grating wheel is set to MIRROR.

The following parameters are used to define NIRSpec Imaging observations.

FieldDetailsValueNotes
General Information
Observation Numberassign observation numbernumber
Observation Labelprovide observation labeltextoptional
Observation Commentsprovide observation commentstextoptional
Target Nameselect Target Namechoose from listfrom Target List
Special Requirementsspecify special requirementschoose from listif needed
Template specific information
Filterselect a filterchoose from list
Readout Patternselect readout patternchoose from list
Number of Groups/Integrationspecify number of groups/integrationnumber
Number of Integrations/Exposurespecify number of integrations/exposurenumber

 General information  

The following parameters are generic to all templates, and are not discussed in this article: Observation Number, Observation Label, Observation Comments, Target Name, and Special Requirements.

Target Name  

Select the TARGET NAME [TBD] from the list of targets previously entered (see list of targets).

 Filters  

For each exposure to be executed , specify the FILTER, READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION, and NUMBER OF INTEGRATIONS/EXPOSURE .

Filter

FILTER [FILTER] = F140X, F110W, F070LP, F100LP, F170LP, F290LP, CLEAR

Select the name of the filter you wish to use.  

Readout Pattern

READOUT PATTERN [READOUT PATTERN] = NRS (default), NRSRAPID, NRSIRS2, NRSIRS2RAPID

This field specifies the readout pattern to be used to obtain the image 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 NRSIRS2 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 100s overhead.

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] specifies the number of times the integration is performed. 

Note for developers: The SUBARRAY is not explicitly given, and its value is FULL for the purposes of calculating photon collection time.

Change log

 Click here to expand...

Version 3 (April 19, 2019)

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


Version 2 (October 17 2017)

  1. PR 88968 - revised overhead time for switching between IRS and IRS2 readout patterns
  2. PR 88047 - added restriction on NGroups x NINTs for IRS2 readout patterns.


Version 1 (June 15, 2017)

  1. This is the converted Word File from Chapter 39.
  2. PR 87895 - revised names of Number of Groups and Integrations
  3. To match GUI - removed restriction on NINTs that was never implemented