NIRISS Imaging Template Parameters

JWST's NIRISS imaging template, available in the Astronomer’s Proposal Tool (APT), has parameters for specifying and scheduling observations.


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 NIRISS Imaging template is used for the direct imaging mode of NIRISS, and this article describes allowed values for all parameters. Advice on how to choose values which optimize your science can be found in the NIRISS Imaging APT Template article.

The NIRISS Imaging template consists of the following parameters:

FieldDetailsValues Notes
General Information   
 Observation Numberassign observation number


Observation Label provide observation labeltextoptional
Observation Commentsprovide observation commentstextoptional
Target Nameselect Target Namechoose from listfrom Target List

ETC Wkbk. Calc. ID

specify ETC Workbook Calculation IDnumberfor science exposures (optional) and target acquisition exposures
Mosaic Propertiesspecify mosaic parametersnumberif needed
Special Requirementsspecify special requirementschoose from listif needed
Template Specific Information   
Image Dithersselect Dither Namechoose from list
Dither Pattern Sizeselect Dither Pattern Sizechoose from list
select Filter name

choose from list

select Readout Pattern

choose from list

specify Number of Groups per integration


specify Number of Integrations per exposure


General Information 

The following parameters are generic to all templates, and are not discussed in this article: Observation Number,  Observation Label, Observations Comments, Target Name, ETC Wkbk. Calc. ID, Mosaic Properties, and Special Requirements.


The following parameters define the dithers for NIRISS Wide Field Slitless Spectroscopy.

Note to developers: Dithers are specified in the PRD table NirissWfssSecondary, EXCEPT the 3-DIRECT-* patterns are not included.

Image Dithers 

IMAGE DITHERS [DITHER PATTERN TYPE] = NONE, 2, 3, 4 (default), 6, 8, 12, 16

This field specifies the number of dither points (see NIRISS Imaging Dithers).  (warning) Dither = NONE is strongly discouraged for NIRISS Imaging of science targets.

Dither Pattern Size 


This field specifies the size or amplitude of the dither steps  (see NIRISS Imaging Dithers).


Exposures are grouped by filter. For each set of exposures, specify the FILTER, READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION, and the NUMBER OF INTEGRATIONS/EXPOSURE

For more information on defining an exposure specification, see Filters in the NIRISS Imaging APT Template article .

 Filter Name   

FILTER [FILTER] = F090W, F115W, F140M, F150W, F158M, F200W, F277W, F356W, F380M, F430M, F444W, F480M

Select the name of each filter  to be used to obtain the data. For the filter bandpasses, see NIRISS Filters.

Readout Pattern   


This field specifies the readout pattern to be used to obtain the data. 

Number of Groups/Integration    

NUMBER OF GROUPS/INTEGRATION [NGROUPS] specifies the number of groups in an integration. (warning) If READOUT PATTERN = NIS, the range is 1-200, while for NISRAPID the range is 1-30.

Number of Integrations/Exposure    

NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the integration is repeated.  (warning)The range is 1-10.

Change log

The initial version of this chapter was provided by Lily Liu.

December 16, 2022

  1. PROPINSTJWST-91556 In Introduction, removed recommendation for parallel.

May 16, 2022

  1. PROPINSTJWST-91239  Added Dither Pattern section

Version 7 (August 8, 2021)

  1. Editorial change - Anchor links fixed in parameter table by removing pagename from link.

Version 6 (April 18, 2019)

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

Version 5 (August 10, 2018)

  1. PR 90964 - Updated Introduction; removed Subarray section

Version 4 (September 18, 2017)

  1. PR 87895 - updated Exposure field labels to Groups/Integration and Integrations/Exposure

Version 3 (September 12, 2016)

PR 85567 - added warning in Introduction about only using this template as a coordinated parallel

Version 2 (September 1, 2016)

PR 85546 - removed subarrays SUB64, SUB128, SUB256

Version 1 (March 8, 2016)

This is the converted Word File from Chapter 40.