Target Groups

The Target Groups form is used to gather multiple close fixed targets into a set for use in one JWST observation. The Astronomer’s Proposal Tool (APT) is used to enter the targets into the proposal.


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.

Target groups are a collection of fixed targets  that are very close on the sky and intended to be observed together in one visit. The name of the target group is then selected as the target for an observation and that observation will be executed for all the targets in the group.  This category of target specification may only be used with the following templates: MIRI LRS , MIRI MRS , NIRSpec Fixed Slit , and NIRSpec IFU .  


Each target group in your proposal will be assigned its own unique number (which can be changed by the user) by APT (they go from 1 to 999).


NAME provides a unique designation for a target group for use throughout the proposal, and should be a short descriptive name for the collection of targets.

Target selection       

TARGET SELECTION allows you to pick the fixed targets in the proposal that you would like to observe as a group (such as a tight cluster of objects, or an object and a background pointing). Note that the targets will be observed in target number order.

(red star)The fixed targets must be within the Visit Splitting Distance (30-80 arcsec depending on Galactic latitude).


This (optional) field should include any additional information that you wish to supply. Comments are not interpreted by the software, but are maintained in the data base and do appear in the operational PDF output.

Change log

General notes


Change log

Version 4 (April 16, 2019)

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

Version 3 (November 8, 2018)

  1. No PR - editorial change, updated link for Visit Splitting Distance.

Version 2 (June 19, 2018)

  1. PR 89938 - removed requirement for fixed (zero-width) APERTURE_PA_RANGE

Version 1 (December 15, 2017)

  1. Initial version (includes PR 64374)