NIRCam Wheel Exercise Template Parameters

JWST's NIRCam Wheel Exercise Engineering template, available in the Astronomer’s Proposal Tool (APT), is used for calibration observations for the NIRCam instrument.


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 rotate the specified wheel 360o. Note that this type of observation cannot be obtained as a parallel to normal science observations, but can be in parallel with slews.

The NIRCam Wheel Exercise template consists of the following parameters:

General Information
Observation Numberassign observation number


Observation Labelprovide observation labeltextoptional
Observations Commentsprovide observation commentstextoptional
Special Requirementsspecify special requirementschoose from listif needed
Template Specific Information

specify Mechanism type

choose from list

specify number of integrations


specify Wheel

choose from list

General Information    

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

Mechanism Type 


This parameter specifies the mechanism type to be exercised.

Number of Rotations 

NUMBER OF ROTATIONS [NROTATIONS] specifies the number of times to rotate the selected wheel(s); (warning)the values are between 1 and 6, inclusive.



This parameter specifies the wheel(s) to be exercised. You may specify one wheel, more than one wheel (up to all four) or ALL. Specifying a list of two to four wheels will exercise those wheels serially and in the order specified. Specifying ALL exercises all four wheels in parallel.

Change log

The documents I used in preparing this chapter are the Preliminary Definition of Observing Templates for JWST Engineering Activities (Beck, Aug. 2008, Final) , the Eng/Cal templates powerpoint presentation of Balzano (May 2008), and the NIRCam OCD (Sahu, V4, Jan 2008).  Updates from the December 2, 2008 meeting are also included (new vocabulary, Readout Region à Subarray, Detector à Module, clarify need for filter pairs).

Version 2 (April 17, 2019)

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

Version 1 (March 30, 2017)

This is the converted Word File from Chapter 29.