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James Webb Space Telescope User Documentation

 

 

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

Introduction

These parameters are required to obtain Dark observations. Note that this type of observation can be obtained as a parallel to normal science observations.

The NIRCam Dark template consists of the following parameters:

 FieldDetails Values  Notes 
General Information  
Observation Numberassign observation number

number


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

select Module

choose from list


select Subarray

choose from list


select readout pattern 

choose from list


specify number of groups per integration

number 


specify number of integrations per exposure

number 


specify number of times to repeat the exposure

number


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.

Module  

MODULE [MODULE] = A, B, ALL, A1, A2, A3, A4, ALONG, B1, B2, B3, B4, BLONG

This parameter specifies the module that is to be used. Modules are defined as follows:

Table 1. Modules for NIRCam Darks

Module

Definition

A

All short and long wavelength detectors in Module A

B

All short and long wavelength detectors in Module B

ALL

All detectors in Module A and then all detectors in Module   B

A1-A4

SCA Ax in Module A, where x = 1-4

ALONG

The long wavelength detector in Module A

B1-B4

SCA Bx in Module B, where x = 1-4

BLONG

The long wavelength detector in Module B

Subarray  

SUBARRAY [SUBARRAY] = SUB160, SUB320, SUB640, FULL

This value specifies the region of the SCA that is to be read out. (warning)Subarrays other than FULL can only be specified if MODULE is B. 

Table 2. Readout Regions for NIRCam Darks

Subarray

Rows

Columns

Light Sensitive Columns

FULL

2048

2048

TBD

SUB160

160

160

All

SUB320

320

320

All

SUB640

640

640

All

Note for developers: users can specify one or more combinations of the parameters below for DARKs .

Exposure Specification   

For each exposure, specify the READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION, NUMBER OF INTEGRATIONS/EXPOSURE, and NUMBER OF EXPOSURES/DITHER.

Readout Pattern  

READOUT PATTERN [READOUT PATTERN] = RAPID, BRIGHT1, BRIGHT2, SHALLOW2, SHALLOW4, MEDIUM2, MEDIUM8, DEEP2, DEEP8

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)See Table 3 for the values as a function of READOUT PATTERN.

Number of Integrations/Exposure   

NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the integration is repeated. (warning)See Table 3 for the values as a function of READOUT PATTERN.

Table 3. Number of Integrations/Exposure and Groups/Integration for Darks

Readout PatternNumber of Groups/IntegrationNumber of Integrations/Exposure
RAPID1-10 

1-400

RAPID (MODULES=ALL)

2

1-2

1-20

BRIGHT11-10 
BRIGHT21-10 

1-10

BRIGHT2 (MODULES=ALL)2-10 

1-10

SHALLOW21-10

1-10

SHALLOW41-10

1-10

MEDIUM21-20

1-10

MEDIUM81-20 

1-10

DEEP21-20

1-10

DEEP81-20

1-10

Number of Exposures/Dither   

NUMBER OF EXPOSURES/DITHER [NEXP] specifies the number of times the dark exposure is to be repeated. (warning)The default value is 1.

Change log

 Click here to expand...

General Notes

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).

Change Log

Version 4 (April 17, 2019)

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


Version 3 (April 9, 2018)

  1. PR 89484 - updated exposure constraints for RAPID, BRIGHT2


Version 2 (September 6, 2017)

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


Version 1 (March 30, 2017)

  1. This is the converted Word File from Chapter 29.

Keywords

JWST NIRCam Dark Template

JWST NIRCam Dark template parameters

Format definitions

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

 (warning)Red text indicates restrictions on a parameter.

 Brown text indicates notes for the developers.

 Green text indicates the name of the parameter used by Commanding.

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JWST Proposal Parameters

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